MARIO DONINELLI
SYSTEMS WITH RADIANT PANELS
SYSTEMS WITH RADIANT PANELS
MARIO DONINELLI
4
andbooks Caleffi
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MARIO DONINELLI
SYSTEMS WITH RADIANT PANELS
SYSTEMS WITH RADIANT PANELS
MARIO DONINELLI
4
andbooks Caleffi
andbooks Caleffi
MARIO DONINELLI
SYSTEMS WITH RADIANT PANELS
andbooks Caleffi
INTRODUCTION
This radiant panel equipment Handbook comes out at the same time as the manifolds system Handbook. First of all (ie. with the third Handbook), we considered that we should focus our attention on manifold systems, as these are the most popular at present and are therefore of greater design interest. However, we did not wish to delay the presentation of panel systems excessively. In fact, we consider that these systems are now likely to extend to Italy the distribution and success they have achieved - and are still achieving - in the technologically more advanced countries of Northern Europe. We also consider that their distribution and success can be assisted by clear, thorough information which is easy to understand. And this is the spirit in which we have tried to provide our contribution. As amply illustrated in this Handbook, there is no longer any reason to doubt the validity of panel systems, and it is therefore important to look at these without prejudice and with careful attention. Knowing how to design and produce these systems in fact makes it possible to complete and qualify the range on offer. And this is most important, in a sector like ours, where everything changes very quickly and one can no longer stay tucked away in a cosy niche market. There is a continuous need to learn; we must know how to adapt to the requirements of a continuously changing world. Only in this way can we offer technologically advanced solutions, which are competitive and thus able to meet our clients’reasonable demands. Finally, I should like to express my warmest thanks to the Author of this publication and all those who have contributed to writing it. As always, any suggestions, opinions and impressions will be very welcome.
Franco Caleffi Chairman, CALEFFI, S.p.A.
PREFACE
This Handbook offers an analysis of the main aspects of the performance, production and design of floor-mounted (under-floor) radiant panel equipment. This analysis is broken down into three parts. 1) Initially, the aspects inherent in the heating performance of the systems will be examined, followed by the materials, control systems and implementation techniques with which they are normally produced. For their dimensioning, a method of calculation derived from European Standard EN 1264 is proposed. 2) Next, the general structure of the calculation programme is illustrated, with the relevant options and command functions. The programme provides for stand-alone dimensioning of each panel. In other words, it provides for a procedure which varies considerably in relation to that used for manifold systems, where all the branch circuits (from the manifold itself) are dimensioned at the same time. This difference is due to the fact that in systems with manifolds, the heating dimensioning is based on variables which depend only on the individual heat emitters, their construction characteristics and the temperature of the fluid. Unlike these, in panel systems, the “heating surfaces“ are also dimensioned on the basis of variables which depend on the specific nature of the area to be served. This makes methods based on automatic, generalised choices highly complex and not always reliable. 3) Finally, an example will be given in order to assist in the use of the programme and give information on how to select the main project variables. You don’t have to read the whole manual to be able to use the calculation programme. In particular, the chapters on panel dimensioning can be omitted or left until later. The essential purpose of these chapters is in fact to illustrate the formulae and procedures on which the operation of the programme is based. I should like to thank Marco Doninelli and Claudio Ardizzoia for their constant hard work. Finally, I should also like to thank Caleffi for giving me the opportunity to complete this task. Mario Doninelli
NOTES
GENERAL STRUCTURE Definitions, graphs, tables, formulae, command functions, examples and advice are given under items (or headings). Each item, while forming part of the general context, can, in practice, stand alone. The connections between items are indicated by appropriate referrals: each referral is clearly shown in rounded brackets. Graphs, tables and formulae have consecutive numbering linked only to the context of the item in which they are contained. Longer items, sometimes introduced by a short contents list, are broken down into chapters and sub-chapters.
DRAWINGS AND DIAGRAMS The items are supplemented by drawings and diagrams which illustrate the essential functional aspects of the systems, equipment and details described. No installation drawings are enclosed.
SIGNS, SYMBOLS AND ABBREVIATIONS Signs and symbols (relating to mathematics, physics, chemistry, etc.) are those in current use. As far as possible, the use of abbreviations has been avoided; those which are used are specified in each case.
UNITS OF MEASUREMENT The International System has not been rigidly applied. Traditional technical units of measurement have sometimes been used instead, as: 1. they are more immediate and understandable from the practical point of view; 2. they are the actual units of measurement referred to in the working language of the technicians and fitters.
GREEK ALPHABET Physical sizes, numeric coefficients and constants are often represented by letters of the Greek alphabet. These letters are shown below with their pronunciation.
Letters of the Greek Alphabet Upper Case
Lower Case
Name
Upper Case
Lower Case
Α
α
Ν
ν
Β
β
Ξ
ξ
Γ
γ
Ο
ο
∆
δ
Π
π
Ε
ε
Ρ
ρ
Ζ
ζ
Σ
σ
Η
η
Τ
τ
Θ
θ
Υ
υ
Ι
ι
Φ
φ
Κ
κ
Χ
χ
Λ
λ
Ψ
ψ
Μ
µ
alpha beta gamma delta epsilon zeta eta theta iota kappa lambda mu
Ω
ω
Name nu xi omicron pi rho sigma tau upsilon phi chi psi omega
NOTES
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CONTENTS
Part one GENERAL NOTES AND METHODS OF CALCULATION
GENERAL NOTES
Page 3
HISTORIC BACKGROUND..................................................................................................................... ADVANTAGES OF PANEL SYSTEMS .................................................................................................... - THERMAL WELL-BEING .................................................................................................................................. - AIR QUALITY .................................................................................................................................................... - HEALTH CONDITIONS .................................................................................................................................... - ENVIRONMENTAL IMPACT ........................................................................................................................... - HEAT USABLE AT LOW TEMPERATURE ...................................................................................................... - ENERGY SAVING ............................................................................................................................................. LIMITATIONS AND DISADVANTAGES OF PANEL SYSTEMS ............................................................. - LIMITATIONS CONNECTED WITH THE SURFACE TEMPERATURE OF THE FLOOR ............................ - THERMAL INERTIA AND METHOD OF USE OF SYSTEMS ......................................................................... - DISADVANTAGES CONNECTED WITH DESIGN ASPECTS ........................................................................ COOLING OF ROOMS ............................................................................................................................. COST OF PRODUCTION AND MANAGEMENT .................................................................................... APPLICATIONS .....................................................................................................................................
CONSTRUCTION OF RADIANT PANEL SYSTEMS
4 6 6 8 8 8 9 9 10 10 10 11 11 12 12
Page 13
PANEL CONTAINMENT STRUCTURES ........................................................................................................... - INSULATING MATERIALS ............................................................................................................................... - PERIPHERAL JOINTS ....................................................................................................................................... - MAIN JOINTS .................................................................................................................................................... - EDGE JOINTS .................................................................................................................................................... - SLAB .................................................................................................................................................................... - FLOORS .............................................................................................................................................................. DISTRIBUTION OF HEAT-CARRYING FLUID .............................................................................................. - MANIFOLDS ....................................................................................................................................................... - PANELS ............................................................................................................................................................... PRESSURE TEST AND START-UP .....................................................................................................................
14 15 16 16 17 17 17 18 18 19 23
CONTROL SYSTEMS
Page 24
HEAT FLOW EMITTED BY A PANEL
Page 33
CALCULATION PARAMETERS .............................................................................................................. UPWARD HEAT FLOW FROM A PANEL .............................................................................................. - LOGARITHMIC MEAN BETWEEN FLUID TEMPERATURE AND AMBIENT TEMPERATURE ............... - FACTORS RELATING TO PIPE CHARACTERISTICS ..................................................................................... - FACTORS RELATING TO THERMAL RESISTANCE OF FLOOR ................................................................... - FACTORS RELATING TO CENTRE-TO-CENTRE DISTANCE OF PIPES ..................................................... - FACTORS RELATING TO THICKNESS OF SLAB ABOVE PIPES ................................................................. - FACTORS RELATING TO OUTER DIAMETER OF PIPE ............................................................................... TOTAL HEAT EMISSION FROM A PANEL ............................................................................................
DIMENSIONING OF PANELS
34 36 37 38 39 40 41 42 43
Page 44
CALCULATION OF PANELS ............................................................................................................................... PARAMETERS REQUIRED .................................................................................................................................. - CENTRE-TO-CENTRE DISTANCES ................................................................................................................. - PRESET HEAD ................................................................................................................................................... - MAX. DESIGN TEMPERATURE ...................................................................................................................... - HEAT OUTPUT REQUIRED ............................................................................................................................. - AMBIENT TEMPERATURE .............................................................................................................................. - TEMPERATURE OF ROOM OR GROUND BELOW ...................................................................................... - THERMAL RESISTANCE OF FLOOR ............................................................................................................... - THERMAL RESISTANCE UNDER PANEL ...................................................................................................... PARAMETERS TO BE DETERMINED ................................................................................................................ - SURFACE TEMPERATURE OF FLOOR ............................................................................................................ - TEMPERATURE DIFFERENCE OF HEATING FLUID .................................................................................... - FLOW IN PANEL ............................................................................................................................................... - HEAD REQUIRED ............................................................................................................................................. - LENGTH OF PANEL .......................................................................................................................................... - FLUID VELOCITY .............................................................................................................................................. - TOTAL HEAT OUTPUT EMITTED BY PANEL ............................................................................................... - HEAT OUTPUT EMITTED DOWNWARDS .................................................................................................... - MEAN HEAT OUTPUT EMITTED UPWARDS BY ONE METRE OF PIPE ................................................... - MEAN HEAT OUTPUT EMITTED DOWNWARDS BY ONE METRE OF PIPE ...........................................
45 50 50 51 51 52 52 53 54 58 62 62 64 64 65 65 66 66 66 66 66
Part two PROGRAMME FOR THE DIMENSIONING OF SYSTEMS WITH PANELS
PRINTER CONFIGURATION
Page 68
MATERIALS ARCHIVES
Page 69
ZONE VALVE ARCHIVE ...................................................................................................................................... ARCHIVE OF VALVES FOR HEAT EMITTERS ................................................................................................ HEAT EMITTERS ARCHIVE ...............................................................................................................................
GENERAL DATA ARCHIVES
70 72 74
Page 77
MAIN PARAMETERS ARCHIVE ......................................................................................................................... MANIFOLD DATA ARCHIVE ............................................................................................................................. DATA ARCHIVE FOR PIPES AND CENTRE DISTANCES .............................................................................
PROJECT ARCHIVE MANAGEMENT
Page 82
CALCULATION PROGRAMME
Page 83
MANIFOLD MANAGEMENT AND PROCESS PRINTING ...................................................................... BRANCH CIRCUITS MANAGEMENT .................................................................................................... PANEL DIMENSIONING ........................................................................................................................ - ACQUISITION OF PROJECT DATA ................................................................................................................ - DEVELOPMENT OF CALCULATIONS ............................................................................................................. - PRESENTATION OF THE DATA PROCESSED ............................................................................................... CALCULATION OF HEAT EMITTERS .................................................................................................... - ACQUISITION OF PROJECT DATA ................................................................................................................ - DEVELOPMENT OF CALCULATIONS ............................................................................................................. - PRESENTATION OF THE DATA PROCESSED ............................................................................................... SELECTION OF SOLUTIONS PROCESSED .............................................................................................
78 80 81
84 85 86 86 88 89 90 90 91 91 92
Part three EXAMPLE OF CALCULATION
EXAMPLE OF CALCULATION USING CALEFFI SOFTWARE ............................................................... - ANALYSIS AND SELECTION OF MAIN PARAMETERS ................................................................................ - SELECTION OF MANIFOLDS AND VALVES ................................................................................................... - SELECTION OF PIPE AND CENTRE-TO-CENTRE DISTANCES ................................................................... - NOTES AND CONVENTIONS USED ............................................................................................................... - ACTIVATION OF PROJECT FILE ..................................................................................................................... - DIMENSIONING BRANCHES .......................................................................................................................... - PRINT-OUT AND SYMBOLS ............................................................................................................................ - DIMENSIONING THE DISTRIBUTION NETWORK ..................................................................................... - CALCULATION OF TOTAL HEAT OUTPUT ..................................................................................................
BIBLIOGRAPHY
94 96 100 100 101 102 103 128 130 130
Page 136
GENERAL NOTES AND METHODS OF CALCULATION
Summary
GENERAL NOTES RUGOSITÀ
CONSTRUCTION RUGOSITÀ OF RADIANT PANEL SYSTEMS
CONTROL SYSTEMS RUGOSITÀ
FLOW OF HEAT RUGOSITÀ FROM A PANEL
PANELRUGOSITÀ DIMENSIONING
3
GENERAL NOTES
HISTORIC BACKGROUND THERMAL COMFORT
AIR QUALITY
HEALTH CONDITIONS
ADVANTAGES OF PANEL SYSTEMS ENVIRONMENTAL IMPACT
HEAT AVAILABLE AT LOW TEMPERATURE
ENERGY SAVING
LIMITATIONS CONNECTED WITH SURFACE TEMPERATURE OF FLOOR
LIMITATIONS AND DISADVANTAGES OF PANEL SYSTEMS
THERMAL INERTIA AND METHOD OF USE OF SYSTEM DISADVANTAGES LINKED WITH DESIGN ASPECTS
COOLING OF ROOMS
COST OF CONSTRUCTION AND MANAGEMENT
APPLICATIONS
4
HISTORICAL BACKGROUND It may be of use to analyse the history of panel heating to give a better overall view of its development in the context of systems in general, and, in particular, this may serve to illustrate why these systems are sometimes seen with a certain diffidence, and used only for applications which are entirely secondary and partial.
THE FIRST FLOOR-HEATING SYSTEMS
The idea of using the floor as a heat emission surface goes back over two thousand years. Heating systems inspired by this idea were built by the Chinese, Egyptians and Romans. The system adopted by the Chinese and the Egyptians was fairly simple. It consisted of building an underground hearth and sending smoke under the flooring of the rooms to be heated; it was, in practice, single room heating. The Romans, however, used far more complex, advanced systems. Using the smoke from a single external hearth, they were able to heat several rooms and even several buildings, thus achieving the first central-heating type system. However, it was not until the start of this century that underfloor heating appeared in its present form. And it was an Englishman, Professor Baker, who was first to patent this type of system using the title “systems for heating rooms with hot water carried by underfloor piping”. In London in 1909, Crittal Co. acquired the patent rights and heated one of the Royal palaces with this new system. However, it was not until the period of the great reconstruction after the second world war that a significant spread of panel heating took place.
POST-WAR SYSTEMS
In the early years after World War II, there were two main reasons for the spread of panel heating - these were the constant unavailability of heat emitters and the ease of insertion of the panels in prefabricated floor slabs. The technique used consisted of burying 1/2” or 3/4” steel tubes in the flooring, without overlying insulating materials. In Europe, from 1945 to 1950, over 100,000 homes were heated by this technique. Very soon, however, it was noted that the equipment was causing numerous physiological problems, such as poor circulation, high blood pressure, headaches and excessive sweating. Problems of this nature were so serious and well-documented that certain European countries set up Commissions to identify the causes.
5
CAUSES OF PHYSIOLOGICAL PROBLEMS
The results of the various Commissions of enquiry agreed that, in the systems constructed, the physiological problems were due to two values being too high: (1) the surface temperature of the flooring, and (2) the thermal inertia of the floor slabs. It was demonstrated in particular that, in order to avoid feelings of discomfort, the floor temperature should not exceed 28÷29°C. In fact, in the systems examined, far higher temperatures were found, even in excess of 40°C. It was also demonstrated that the excessive heat accumulated in the floor slabs of the systems meant overheating of the rooms above physiologically acceptable levels. The Commissions themselves, however, did not publish any negative judgements of panel systems. They demonstrated that these systems, if constructed for a low surface temperature and with a not excessively high thermal inertia, can offer heat comfort greatly superior than that which can be obtained with radiator or convector equipment. Whilst not being a condemnation, the Commissions results in fact constituted a strong dis-incentive to produce panel systems, and it was some years before they made any significant comeback.
THE NEW SYSTEMS
The event which again drew attention to these systems was the energy crisis in the 1970s. Under the impetus of this crisis, almost all European countries issued laws which required efficient heat insulation of buildings, and it was thus possible to heat rooms with less heat and so (in the case of panels) with lower floor temperatures. In addition, in most cases, the degree of insulation required made it possible to heat the rooms with floor temperatures lower than the physiological maximum, and this in turn made it possible to reduce the thermal inertia of the system. A further reduction in thermal inertia was obtained by producing “floating” floors with heat insulation either under the panels or towards the walls. And it was precisely this innovation, of a legislative and technical nature, which finally made it possible to produce thoroughly reliable panel systems with a high heat output. Nowadays in Europe, the “new” panel systems are installed mainly in the Northern countries, where they are experiencing a deserved success, largely due to the advantages (analysed below) which they can offer.
6
ADVANTAGES OF PANEL SYSTEMS The main advantages offered by panel systems relate to: - heat comfort, - air quality, - hygiene conditions, - environmental impact, - the heat usable at a low temperature, - energy saving.
HEAT COMFORT
As shown by the ideal curve shown opposite, in order to ensure comfortable heat conditions in a room, slightly warmer areas must be maintained at floor level and slightly cooler ones at the ceiling level. The system most suited to providing these conditions consists of radiating floors, for the following reasons: 1. the specific position (i.e. on the floor) of the panels; 2. the fact that they give off heat above all by radiation, thus avoiding the formation of convection currents of hot air at ceiling level and cold air at floor level.
7
8
AIR QUALITY
Panel heating can prevent two inconveniences which are typical of systems with heat emitters: 1. burning of the dust in the air, which can cause a feeling of thirst and irritation of the throat; 2. high dust circulation which (especially in rooms which are not regularly cleaned) can cause allergies and respiratory problems.
HEALTH CONDITIONS
Panel systems have a positive contribution to maintaining good environmental health conditions as they prevent: 1. the formation of damp floor areas, thus removing the ideal conditions for dust mites and bacteria; 2. the occurrence of moulds (and the related bacterial fungi) on the walls bordering the heated floors.
ENVIRONMENTAL IMPACT
In new buildings and refurbishment works with renewed flooring, panel systems have the least environmental impact because: 1. they do not impose any aesthetic requirements. The invisible nature of the panels is of great importance, especially when air-conditioning buildings of historic or architectural importance, where the presence of heater emitters can compromise the balance of the original spaces; 2. they do not restrict freedom of layout, thus allowing the most rational use of the available space; 3. they do not contribute to deterioration of plasterwork, wooden flooring and hardware, as: • they
do not dirty the walls with convection stains;
• they
do not allow formation of damp at floor level;
•
they considerably restrict cases of internal condensation, as they increase the temperature of the walls near the panel floor slabs.
9
HEAT USABLE AT LOW TEMPERATURE
Due to their high dispersion area, panel systems can use the heat-carrying fluid at low temperatures. This characteristic makes their use convenient with heat sources whose efficiency (thermodynamic or economic) increases when the temperature required is reduced, as in the case of: •
heat pumps,
•
condensing boilers,
•
solar panels,
•
heat recovery systems,
•
district heating systems, with heat cost linked (directly or indirectly) to the return temperature of the primary fluid.
ENERGY SAVING
In comparison with the traditional heating systems, panel systems produce considerable energy savings, for two basic reasons: 1. the higher operating temperature, which permits (for the same ambient temperature) average savings varying from 5 to 10%; 2. the lower temperature gradient between floor and ceiling, which provides higher energy savings the larger and higher the rooms. The following are also (although admittedly less important) reasons for energy savings: • the
use of low temperatures which reduces dispersion along the piping,
• the
non-heating of the walls behind the radiators,
• the
lack of convection movement of the hot air over glazed surfaces.
On average, panel systems, in comparison with traditional systems, produce energy savings of between 10 and 15%.
10
LIMITATIONS AND DISADVANTAGES OF PANEL SYSTEMS These relate mainly to aspects connected (1) with the surface temperature of the floor, (2) the thermal inertia of the system and (3) difficulties of a design nature.
LIMITATIONS CONNECTED WITH THE SURFACE TEMPERATURE OF THE FLOOR
In order to avoid conditions of physiological discomfort, the surface temperature of the floor must be below the values given under the heading DIMENSIONING OF PANELS, sub-chapter SURFACE TEMPERATURE OF THE FLOOR. As specified in the said sub-chapter, these values make it possible to determine the maximum heat output (Qmax) which can be transferred by a panel. If Qmax is less than the required output (Q), there are two possible situations: 1. Qmax is less than Q only in a few rooms, in which case additional heat emitters can be used. For example, Qmax can come from the panels and the remaining output from radiators. 2. Qmax is less than Q in all or most of the rooms, a traditional type system should be used.
THERMAL INERTIA AND METHOD OF USE OF SYSTEM
Panel systems are characterised by having a high thermal inertia as, in order to transfer heat, they use the structures in which the panels themselves are buried. In environments heated with a certain degree of continuity (and good insulation under the panels), the thermal inertia of the system poses no problems and permits: •
good adaptability of the system to the external climatic conditions;
•
interruptions or slowing down of functions, with system ‘on’ and ‘off’ times which are normally two hours advanced.
On the other hand, in environments which are only heated for brief periods (such as weekend homes), the thermal inertia of the panel system has considerable phase variations between the starting times and the times of actual use. Thus in these cases, other heating systems should be used.
11
DISADVANTAGES LINKED WITH DESIGN ASPECTS
Unlike the traditional systems with heat emitters, panel systems require: •
greater commitment to determining project parameters. In fact, apart from the parameters required to determine the heat losses from the rooms, the design of panel systems also requires detailed knowledge of all the constructional information regarding the floors and floor slabs.
•
more complex, laborious calculations, although due to the greater commitment, these can be considerably reduced with the use of computers.
•
less adaptation to variants during the work or when the system is completed, as it is not possible to add or remove panel portions, as is done with radiators.
COOLING ROOMS Panel systems also permit cooling of premises. It should however be considered that these have two very clear limitations: 1. the limited cooling output, 2. the inability to dehumidify. The low cooling output depends on the fact that in panel systems it is not possible to reduce the floor temperature too far without causing surface condensation phenomena. For this reason, it is difficult to obtain a cooling output greater than 40-50 W/m2. The inability to dehumidify depends in fact on the nature of the panel system itself, whose surfaces (i.e. the floor) cannot cause condensation and evacuation of part of the water contained in the air. Healthy hygrometric conditions can, therefore, only be obtained with the use of dehumidifiers, in conjunction with panel systems, with a cost and space requirement which is not always acceptable.
12
CONSTRUCTION AND DESIGN COSTS It is practically impossible to establish significant mean data with regard to the costs of installing panel systems, as there are too many variables involved, such as: – the type of system (stand-alone or centralised), – the control system, – the heat resistance of the floors, – the costs of other insulating materials to be laid below the panels, – the cost and quality of the pipe forming the panels. It can however be assumed that panel systems will cost on average 10% to 30% more than radiator systems with climatic control. With regard, however, to running costs, panel systems allow savings averaging 10 to 15% in comparison with traditional systems (see sub-chapter ENERGY SAVING). They thus allow the additional construction cost to be offset relatively quickly.
APPLICATIONS On their own, or integrated with air-conditioning systems, panel systems can be used to heat: detached and terraced houses, homes in high-rise blocks, nursing homes, schools, gyms, swimming pools, museums, libraries, hospitals, hotels, shops and workshops. They can also be used to clear ice and snow - car parks, garage ramps, steps, runways and sports fields.
13
CONSTRUCTION O F R A D I A N T PA N E L S Y S T E M S
INSULATING MATERIALS
PERIPHERAL JOINTS
MAIN JOINTS
PANEL CONTAINMENT STRUCTURES EDGE JOINTS
SLABS
FLOORS
MANIFOLDS
DISTRIBUTION OF HEAT-CARRYING FLUID PANELS
PRESSURE TEST AND START-UP
14
PANEL CONTAINMENT STRUCTURES These consist mainly of the floor (or solid foundation on the ground), the insulating material, the slab and the floor tiles or finish.
15
INSULATING MATERIALS
The insulation under the panels is used (1) to reduce the heat given off downwards and (2) to limit the thermal inertia of the system. The most commonly used insulating materials are polystyrene and polyurethane. Sometimes, lightened concretes are also used, but their use is generally not recommended, because they have high thermal inertia values. Insulation systems can have flat surfaces or pre-formed surfaces for direct anchorage of the pipes. Flat surface insulation materials are normally used in buildings to insulate traditional floors. As they have no supports for anchoring pipes, they require the use of electro-welded frameworks or suitable metal profiles with junction clips and fixing supports. The most frequently used flat surface insulating materials are expanded and extruded polystyrene. The latter, in particular, due to form and high density, make it possible to produce very compression-resistant floors. Pre-formed insulation, on the other hand, is made specifically for the panel system. Its surfaces have profiles and grooves which allow the pipes to be fitted directly. These insulators have the advantage of speeding up the fitting of the panels. They are, however, not highly compression-resistant and thus cannot be used to make floors subject to compression stresses, such as for example industrial flooring. If several materials are to be used for making the insulating layer, the least compression-resistant materials must be positioned in the upper layers. In addition, the insulating panels must be fitted in close contact with each other and (in the case of multiple layers) have offset joints. In order to prevent deterioration of the insulating materials in use, two types of protection must be provided for: 1. Protection against the dampness of the concrete. This is always required and can be made above the insulation with polyethylene sheets (min. thickness 0,15 mm) or other equivalent protection; 2. Protection against rising damp. This is only required for floors in direct contact with the ground or in very damp rooms. It can be made under the insulation with polyvinyl chloride sheets (min. thickness 0,4 mm) or other equivalent protection
16
PERIPHERAL JOINTS
These are used to provide (1) expansion of the floor slab, (2) heat insulation between the slab and the walls, (3) a sound gap between floor and walls. This is done using insulating strips (normally expanded polyethylene 6÷8 mm thick) positioned along the walls and bounding the various construction elements of the floor and slab (see diagram in the chapter PANEL CONTAINMENT STRUCTURES). The strips must be positioned carefully and overlapped by at least 10 cm at the junction points. Their upper parts must protrude beyond the block and be trimmed only when the floor is finished.
MAIN JOINTS
These permit expansion of the slab at the locations of the structural joints of the building and in the case of large floor areas. Without joints of this type, constructing floors of area exceeding 40 m2 or of length greater than 8 m is not advisable. In L-shaped rooms, the maximum area can be extended to 80 m2.
17
EDGE JOINTS
These are used to guide the positioning of the slab in relation to doors and other openings. They are made using a trowel (up to a depth of 3÷4 cm) when the slab begins to dry.
SLAB
This must be made with a fluid mixture to prevent the formation of small air pockets which can obstruct normal heat transfer. Appropriate chemicals can be added to improve the fluidity of the casting. The components and proportions of the mix depend on the class of strength to be obtained. The minimum thickness of the slab over the pipes must be: •
20 mm
for flush slabs, i.e. for slabs on which a sub-base is to be made later, onto which the tiles will be fitted.
•
40 mm
for finish slabs, i.e. for slabs on which the floor is to be laid or “stuck” directly afterwards.
TILES (FLOOR FINISH) Panel systems do not require special types of flooring or special techniques for fitting. However, it is advisable not to use floor finishes with a thermal resistance greater than 0,150 m2K/W (see item PANEL DIMENSIONING, sub-chapter FLOOR THERMAL RESISTANCE).
18
DISTRIBUTION OF THE HEAT-CARRYING FLUID This consists of taking the fluid through the main distribution system, the manifolds and the panels. For the development and dimensioning of the main system, see the 2nd Caleffi Handbook; the main characteristics of the manifolds and the panels are exami-ned below.
MANIFOLDS
These are normally made of brass with independent flow and return connections. For correct operation and maintenance of the system, they must have: – main on/off valves, – panel on/off valves, – micrometric panel regulating valves, – automatic air vents, – drain cocks.
19
PANELS
The analysis of their main characteristics is broken down into three parts: – the choice of pipes, – the formation of the panels, – the installation of the pipes.
Selection of pipes
Plastic pipes are the most suitable for forming the panels, being different from metal pipes in that they: • are easy to install, • are not subject to corrosion, • do not allow the formation of scale. Normally, cross-linked polyethylene (PEX), polybutene (PB) and polypropylene (PP) pipes are used. All the plastic pipes must have barriers to prevent the diffusion of oxygen. The oxygen contained in the air must be prevented from diffusing into the pipes, as this gas can cause corrosion of the boiler and any metal pipework. The diameters usually used for making the panels are 16/13 and 20/16. 12/10 and 25/20 are used only for special applications.
Formation of the panels
Each room must be heated with one or more specific panels. This makes it possible to control room temperatures independently, in other words without altering the heat balance of other rooms. The panels can be made spiral or coiled. These are systems which, with the same distance between centres and surface, deliver the same amount of heat, but the spiral system is generally preferable as: •
it provides a more even surface temperature as (unlike the case of the coil), its flow and return pipes lay alternately;
•
it is easier to implement, as the shape of the spirals only requires two bends at 180° to the central ones, in other words those in which the formation of the spiral is inverted.
The coil formation is suited above all to rooms of irregular shape or special applications, such as, for example, de-icing ramps.
20
The panels can have constant or variable centre-to-centre distances with pipes closer together where there are areas of glass or highly dispersive walls.
21
With coil panels, the flow must be towards the outer walls in order not to increase the already sensitive differences in surface temperature at the floor, which characterise this distribution system. The distances between pipes and the structures bounding the environment must be at least: • 5 cm in the case of walls and pillars, • 20 cm in the case of flue ducts, fireplaces and lift shafts. The pipes of the panels must not interfere with discharge pipes and must not pass under sinks, shower trays, WCs or bidets, unless these are of the suspended type.
22
Installation
The pipes must be transported, stored and fitted in such a way as to avoid site damage and direct exposure to sunlight. Various systems can be used when installing the pipes, such as: • pre-formed insulation of appropriate profiles and grooves, • electro-welded frameworks with fixing clips or clamps, • metal profiles with fitting and jointing clips. In all cases, only fitting systems must be used which are able to: – permit good pipe anchorage, – prevent damage to the pipes themselves (metal connections are not permitted), – permit the design centre-to-centre distances to be implemented. It is advisable not to pass pipes through the main expansion joints. If this is not possible, the work must be done in such a way that: 1. the expansion joints of the building are only crossed by the pipes of the main distribution system; 2. the other main joints are crossed only by pipes protected with a sheath of compressible material of • min. length 30 cm on either side of the joint, • diameter double the external diameter of the pipe.
23
PRESSURE TEST AND START-UP Before covering with concrete, the panels must be tested at a pressure at least equal to the working pressure, with a minimum of 6 atm. This pressure must be maintained and constantly checked throughout the spreading of the concrete. If there is a risk of frost, antifreeze additives compatible with the panel pipes should be used. The system must not be activated until the slab and the floor are completely dry. In general, this takes at least 21 days from casting. The use of synthetic additives makes it possible to reduce this period considerably, but it will still be not less than 7 days. The heating must be started maintaining a flow temperature of 25°C for at least 3 days. Subsequently, the flow temperature can be gradually raised to the design value.
24
CONTROL SYSTEMS
Climatic control with pre-assembled unit
Climatic control with 3-way valve
Climatic control with 2-way valve upstream from a heat exchanger
Fixed point regulation with 3-way valve and anti-condensation pump
Climatic control with 3-way valve and anti-condensation pump
Climatic control with 3-way valve, anti-condensation pump and by-pass
25
Panel system control equipment must be able to: 1. permit the heat transfer required to take place in such a way as to optimise the heat comfort and energy saving; 2. prevent excessively hot fluid from being distributed to the panels, as this could cause breakage and cracking of the flooring and wall structures; 3. prevent flue condensation in the boiler, so as not to cause corrosion problems which could endanger the boiler itself. In order to optimise the heat emission, climatic type controls should usually be adopted. In fact these controls make it possible to minimise the heat accumulated in the floor slabs and thus in turn to minimise the time required for the system to respond to variation of the required heat output. Either simple climatic controls or integrated climatic controls with thermoelectric valves interlocked with room thermostats can be conveniently adopted. Fixed point controls are suggested only for systems which are not working continuously, used for example to heat churches, theatres or exhibition rooms. However, in order to prevent the flow of excessively hot fluid to the panels, the system must be provided with a safety sensor able, when the preset limit is exceeded, to close the control valve and shut down the system pump. This sensor should be protected against tampering. Finally, in order to prevent flue condensation, the boiler return temperature must be maintained at over 55°C. For this purpose, anti-condensation pumps and motorised valves with override devices can be used. Operating diagrams of the systems most used for controlling panel systems follow.
26
Climatic control with pre-assembled unit
This solution is valid for small to medium-sized systems. Generally, the pre-assembled units available do not permit flows greater than 5.000÷6.000 l/h.
27
Climatic control with 3-way valve
This control can be adopted in systems where there are not problems with flue gas condensation; for example in systems with heat pumps or heat exchangers.
28
Climatic control with 2-way valves upstream from a heat exchanger
This type of control can be used in district heating substations.
29
Fixed point regulation with 3-way valve and anti-condensation pump
This solution is suited to systems operating intermittently, as it minimises the time required to reach the steady condition. It does not, however, allow a good response to output variations in continuous operation.
30
Climatic control with 3-way valve and anti-condensation pump
This system is mainly suited to panel systems of medium and large dimensions. Advantages: It is easy to operate and check, as it is similar to the control systems used in heating plant. Disadvantages: The 3-way valve operates in a limited opening range. In order to prevent chatter and wear on the valve (seat and obturator), high-quality materials and equipment must be used.
31
Climatic control with 3-way valve, anti-condensation pump and by-pass
This system is mainly suited to panel systems of medium and large dimensions. Advantages: The 3-way valve operates throughout its whole opening range, thus preventing any chatter and wear on the valve. Disadvantages: Requires skilled personnel for commissioning and calibration.
32
The diagram on the previous page shows the regulating and by-pass valves dimensioned on the basis of the following flows:
Q tot G v = ————————— 1,16 . ( t m – t r )
(1)
Gb = Gp – Gv
(2)
where: G v = flow through 3-way valve, l/h Q tot = total heat output of panel circuit, W tm tr
= primary circuit flow temperature (boiler circuit), °C = secondary circuit return temperature (panels circuit), °C
G b = by-pass flow, l/h G p = panels circuit flow, l/h
33
F L O W O F H E AT F R O M A PA N E L
CALCULATION PARAMETERS
LOGARITHMIC MEAN BETWEEN FLUID TEMPERATURE AND ROOM TEMPERATURE
FACTOR RELATING TO PIPE CHARACTERISTICS
FACTOR RELATING TO FLOOR THERMAL RESISTANCE
UPWARD FLOW OF HEAT FROM A PANEL
* *
* FACTOR RELATING TO PIPE CENTRE-TO-CENTRE DISTANCE
FACTOR RELATING TO THICKNESS OF SLAB ABOVE PIPES
FACTOR RELATING TO OUTER DIAMETER OF PIPE
TOTAL FLOW OF HEAT FROM A PANEL
*
* *
*
*
In order to be able to use the programme, you do not need to read the chapters and sub-chapters marked with an asterisk (see preface).
34
CALCULATION PARAMETERS The parameters which are used to determine the heat output delivered by a panel can be broken down into the following groups: 1.
parameters relating to the surrounding conditions: - t a room temperature, °C - t s temperature of room or ground below, °C
2.
parameters relating to the panel configurations: covered surface of panel, m2 -S -I pipe fitting centre-to-centre distance, m
3.
parameters relating to the type of pipe: - D e pipe external diameter, m - D i pipe internal diameter, m - λ t pipe thermal conductivity, W/mK
4.
parameters relating to the panel containing structure: - R p thermal resistance of floor, m2K/W - s m thickness of slab above pipes, m - λ m thermal conductivity of the slab, W/mK - R s thermal resistance under panel, m2K/W
5.
parameters regarding the temperature of the heat-carrying fluid: - t e flow temperature of heat-carrying fluid, °C
35
36
UPWARD FLOW OF HEAT FROM A PANEL (1) This is calculated using the following formula: Q = S . ∆t . B . Fp . FI . Fm . FD
(1)
where: Q = upward flow of heat given off by panel, W S = covered surface of panel, m2 ∆ t = logarithmic mean between the temperature of the fluid and the ambient temperature, °C B = factor relating to pipe characteristics, W/m2K Fp = FI = Fm = FD =
(1)
factor relating to thermal resistance of floor, dimensionless factor relating to centre-to-centre distance of pipes, dimensionless factor relating to thickness of slab above pipes, dimensionless factor relating to outer diameter of pipe, dimensionless
There is no need to read this chapter (see Preface).
37
LOGARITHMIC MEAN BETWEEN THE TEMPERATURE OF THE FLUID AND THE AMBIENT TEMPERATURE (1)
This is calculated using the following formula: ( te – tu ) ∆ t = ——————— ( te – ta ) ln ————— ( tu – ta )
where: ∆ t = logarithmic mean of fluid temperature and ambient temperature, °C t e = flow temperature of heating fluid, °C t u = return temperature of heating fluid, °C t a = temperature of ambient air, °C ln = natural logarithm
(1)
There is no need to read this sub-chapter (see Preface).
(2)
38
FACTOR RELATING TO THE PIPE CHARACTERISTICS (1)
This is indicated by the symbol B and it is considered that: B = B 0 = 6,7 W/m2K for pipes with: - s t 0 = 0,002 thickness, m - λ t 0 = 0,350 thermal conductivity, W/mK
For pipes of different thickness and thermal conductivity, the factor (B) is calculated using the formula (3) shown below:
1 1 1,1 1 De 1 De — = —— + —— . F p . F I . F m . F D . I . —— ln —— – —— ln —— B B0 π 2 λt D e – 2s t 2 λ t 0 D e – 2s t 0
(
where: B 0, s t 0, λ t 0 = symbols and values defined above Fp = FI = Fm = FD = I De λt st
= = = =
factor relating to the thermal resistance of the floor, dimensionless factor relating to the centre to centre distance of the pipes, dimensionless factor relating to the thickness of the slab above the pipes, dimensionless factor relating to the outer diameter of the pipe, dimensionless pipe centre-to-centre distance, m outer diameter of pipe, m thermal conductivity of pipe, W/mK thickness of pipe, m
ln = natural logarithm
(1)
There is no need to read this sub-chapter (see Preface).
)
39
FACTOR RELATING TO THE THERMAL RESISTANCE OF THE FLOOR (1)
This is shown with the symbol F p. Its value can be determined from Table 1, or using formula (4).
TABLE 1 - Value of factor F p
Conductivity of slab
Thermal resistance of floor, m2K/W
W/mK
0,00
0,05
0,10
0,15
2,0
1,196
0,833
0,640
0,519
1,5
1,122
0,797
0,618
0,505
1,2
1,058
0,764
0,598
0,491
1,0
1,000
0,734
0,579
0,478
0,8
0,924
0,692
0,553
0,460
0,6
0,821
0,632
0,514
0,433
Fp
given:
α
s m0 λ m0
1 s m0 ——— + ——— λ m0 α = ————————— 1 s m0 ——— + ——— + R p λm α
= 10,8 W/m2K = 0,045 m = 1,0 W/mK
and where: λ m = thermal conductivity of slab, W/mK R p = thermal resistance of floor, m2K/W
(1)
There is no need to read this sub-chapter (see Preface).
(4)
40
FACTOR RELATING TO PIPE CENTRE-TO-CENTRE DISTANCE (1)
Shown by the symbol F I and calculated using the formula: x FI = AI
(5)
where the factor A I can be determined from Table 2 and the exponent x (for pipe centre-to-centre distances varying between 0,050 and 0,375 m) can be calculated using the equation:
I x = 1 – ————— 0,075
(6)
where: I = pipe centre-to-centre distance, m
TABLE 2 - Value of factor A I Rp =
0,00
A I = 1,230
Rp =
0,05
A I = 1,188
Rp =
0,10
A I = 1,156
Rp =
0,15
A I = 1,134
Table symbols: R p = thermal resistance of floor, m2K/W A I = dimensionless factor
N.B.: For centre-to-centre distances greater than 0,375 m, the heat flow (Q) can be calculated using the formula: 0,375 Q = Q (0,375 ) . ———— I
(7)
where Q (0,375 ) represents the heat flow from a panel with centre-to-centre distances equal to 0,375 m.
(1)
There is no need to read this sub-chapter (see Preface).
41
(1)
FACTOR RELATING TO THE THICKNESS OF THE SLAB ABOVE THE PIPES
Shown by the symbol F m and calculated using the formula: y Fm = Am
(8)
where the factor A m can be determined from Table 3 and the exponent y (for thickness of the slab above the pipes greater than 0,015 m) can be calculated using the equation: y = 100 . ( 0,045 – s m )
(9)
where: s m = thickness of the slab over the pipes, m
TABLE 3 - Value of factor A m
Centre-tocentre distance
(1)
Thermal resistance of the floor, m2K/W 0,00
0,05
0,10
0,15
0,050
1,0690
1,056
1,0430
1,0370
0,075
1,0660
1,053
1,0410
1,0350
0,100
1,0630
1,050
1,0390
1,0335
0,150
1,0570
1,046
1,0350
1,0305
0,200
1,0510
1,041
1,0315
1,0275
0,225
1,0480
1,038
1,0295
1,0260
0,300
1,0395
1,031
1,0240
1,0210
0,375
1,0300
1,024
1,0180
1,0160
There is no need to read this sub-chapter (see Preface).
42
FACTOR RELATING TO THE PIPE OUTER DIAMETER (1)
Indicated by the symbol F D and calculated using the formula: z FD = AD
(10)
where the factor A D can be determined from Table 4 and the exponent z (for diameters between 0,010 and 0,030 m) can be calculated using the equation: z = 250 . ( D e – 0,020 )
(11)
where: D e = outer diameter of pipe, m
TABLE 4 - Value of factor A D
Centre-tocentre distance
(1)
Thermal resistance of the floor, m2K/W 0,00
0,05
0,10
0,15
0,050
1,013
1,013
1,012
1,011
0,075
1,021
1,019
1,016
1,014
0,100
1,029
1,025
1,022
1,018
0,150
1,040
1,034
1,029
1,024
0,200
1,046
1,040
1,035
1,030
0,225
1,049
1,043
1,038
1,033
0,300
1,053
1,049
1,044
1,039
0,375
1,056
1,051
1,046
1,042
There is no need to read this sub-chapter (see Preface).
43
TOTAL FLOW OF HEAT FROM A PANEL (1) This is determined using the equation: Q t = ( t e – t u ) . G . 1,16
(12)
where: Q t = total heat output emitted by a panel, W t e = heating fluid flow temperature, °C t u = heating fluid return temperature, °C G = flow through panel, l/h
The flow through the panel can be calculated using the formula (13) given below:
1 sm ——— + R p + ——— λm α Q S . ( ta – ts ) G = —————— . 1 + —————— + ————— ( t e – t u ) . 1,16 Rs Q . Rs
[
given:
α
and where: G
= 10,8 W/m2K
Q
= flow through panel, l/h = upward flow of heat from a panel, W
te tu
= heating fluid flow temperature, °C = heating fluid return temperature, °C
s m = thickness of slab, m λ m = thermal conductivity of slab, W/mK
(1)
Rp Rs
= thermal resistance of floor, m2K/W = thermal resistance under panel, m2K/W
S
= covered surface of panel, m2
ta ts
= temperature of ambient air, °C = temperature of room or ground below °C
There is no need to read this chapter (see Preface).
]
44
D I M E N S I O N I N G O F PA N E L S
CALCULATION OF PANELS CENTRE-TO-CENTRE DISTANCES PRESET HEAD MAX. DESIGN TEMPERATURE HEAT OUTPUT REQUIRED
PARAMETERS REQUIRED
AMBIENT TEMPERATURE TEMPERATURE OF ROOM OR GROUND BELOW THERMAL RESISTANCE OF FLOOR THERMAL RESISTANCE UNDER PANEL
SURFACE TEMPERATURE OF FLOOR TEMPERATURE DIFFERENCE OF HEATING FLUID PANEL FLOW REQUIRED HEAD PANEL LENGTH
PARAMETERS TO BE DETERMINED
FLUID VELOCITY TOTAL HEAT OUTPUT FROM PANEL
HEAT OUTPUT EMITTED DOWNWARDS MEAN HEAT OUTPUT EMITTED UPWARDS BY ONE METRE OF PIPE MEAN HEAT OUTPUT EMITTED DOWNWARDS BY ONE METRE OF PIPE
45
CALCULATION OF PANELS (1) The formulae examined in the previous items make it possible to dimension panel systems. For this purpose, a method of theoretical calculation is presented below, with pre-established head at the ends of the panel. The analysis and development of the proposed method is broken down into the following stages: A. checking the conditions for physiological well-being, B. calculation of the return temperature, C. calculation of the flow, D. calculation of the panel length, E.
calculation of the head losses of the panel,
F.
check on acceptability of required head,
G. calculation and checking of other parameters, H. zone head.
(1)
There is no need to read this chapter (see Preface).
46
A - Checking the conditions for physiological well-being In order to be able to ensure conditions of physiological well-being, the heat output transferred by the panel must not exceed the maximum output defined in sub-chapter SURFACE TEMPERATURE OF THE FLOOR. It must therefore be: Q < Q max = S . q max
(1)
where: Q Q max S q max
= = = =
heat output required from the panel, W maximum output which can be transferred by the panel, W covered surface of panel, m2 specific output which can be transferred by the panel, W/m2
where: q max = 100 W/m2 in continuously occupied environments; q max = 150 W/m2 in bathrooms, showers and swimming pools; q max = 175 W/m2 in perimeter areas of rooms rarely used.
If Q is greater than Q max, a heat output less than or equal to Q max must be emitted by the panel and the remaining output made up by an integrated heat emitter.
B - Determination of the return temperature
Noting the parameters: - heat output required, - panel surface, - maximum design temperature, - ambient temperature, - thickness and conductivity of slab, - thermal resistance of floor, - outer diameter, thickness and conductivity of pipe, - pipe centre-to-centre distance, the return temperature (tu) of the panel is calculated for successive iterations, using the formulae (1) and (2) given under the heading HEAT FLOW FROM A PANEL.
47
There are three possible situations: B1. The return temperature is not lower than the flow temperature.
In this case, the panel is not capable of emitting the required heat, and is therefore under-dimensioned. As an alternative solution, one can: select (if possible) a panel with smaller centre-to-centre distances i.e. a panel with a greater heat output; • provide for an integrated heat emitter. •
B2. The return temperature is not higher than the ambient temperature.
In this case, the panel only operates intermittently in the heat transfer to the environment, and is thus over-dimensioned. As an alternative solution, one can: select (if possible) a panel with larger centre-to-centre distances - i.e. a panel with a lower heat output; • provide for a panel with a smaller emission surface. •
B3. The return temperature is between the flow and ambient tem-
peratures. In this case, the value of the return temperature does not (at least from the theoretical point of view) restrict the acceptability of the solution under consideration. However, the difference between the maximum flow temperature and the return temperature is below the limits given in the sub-chapter TEMPERATURE DIFFERENCE OF HEATING FLUID.
C - Calculation of flow Noting the parameters defined in B, the return temperature (tu), the thermal resistance under the panel and the temperature of the room or ground below, the panel flow can be calculated using the formula (13) given in the previous item.
48
D - Calculation of panel length
The panel length is calculated using the equation:
L = La
+
S —— I
(2)
where: L = panel length, m La = route length (both ways) between manifold and panel, m S = covered surface of panel, m2 I = panel centre-to-centre distance, m
E - Calculation of the head losses of the panel
The total head losses of the panel are calculated by adding together the continuous and localised losses of head, the value of which is determined as follows: - the continuous head losses are calculated by multiplying the length of the panel by the unit head losses; - the localised head losses are calculated by adding together head losses due to: • the panel shut-off valves, • the panel pipe bends (on average these losses are considered to be between 20 and 30% of the continuous head losses).
F - Check on acceptability of required head
On the basis of the value of the head required at the ends of the panel (which coincides with the head losses determined above), there are two possible cases: F1. The head required is lower than that pre-established.
In this case, the panel is acceptable and the difference between the head required and that pre-established is offset by adjustment of the regulating valve provided for each panel.
49
F2. The head required is higher than that pre-established.
In this second case, the solution prepared is not acceptable. As an alternative solution, one can: • select (if possible) a panel with smaller centre-to-centre distances; • consider the possibility of transferring to the room a slightly lower heat output, as a few watts less may take the required head below that pre-established; • provide for an additional heat emitter.
G - Calculation and checking of other parameters
In addition to the limits connected with the temperature of the floor and the pre-established head , solutions whose velocity is too low must also be avoided (see sub-chapter FLUID VELOCITY) In addition, in order to be able to proceed with the dimensioning of the heat generator and other panels, the following parameters must also be determined (see sub-chapter PARAMETERS TO BE DETERMINED): Q t = total heat output emitted by panel, Q s = heat output emitted downwards by panel, e p = mean heat output emitted upwards by one metre of pipe, e s = mean heat output emitted downwards by one metre of pipe.
H - Zone Head
This is calculated by adding together the following: H p = pre-established head at the panel connections, H c = loss of head due to the manifold, H z = loss of head due to the possible presence of the zone valve, H i = loss of head due to main shut-off valves.
50
PARAMETERS REQUIRED In order to be able to dimension a panel, the following parameters must be known:
centre-to-centre distances (in the case of panels with variable centre-to-centre distances); outer diameter, thickness and thermal conductivity of pipe; pre-established head; maximum design temperature; heat output required; manifold-panel travel distance; ambient temperature; temperature of room or ground below; covered surface of panel; thickness and conductivity of slab; thermal resistance of floor finish; thermal resistance under panel; fluid-dynamic characteristics of the manifold and valves.
Those of greatest design interest are examined below:
CENTRE-TO-CENTRE DISTANCES These may vary up to 30 cm in applications of a domestic nature or in permanently inhabited environments. They may, however, vary up to 40 cm in applications of an industrial or commercial nature (e.g.workshops, warehouses or garages). The grid (or series) of possible centre-to-centre distances depends on the fixing supports (framework or profiles) or the pre-formed panels to be used. The most frequently used grids are as follows: 7,5
15,0
22,5
30,0
37,5
5,0
10,0
15,0
20,0
30,0
8,0
16,0
24,0
32,0
40,0
51
PRESET HEAD This is the head which is assumed to be available at the ends of the panel. It is generally agreed that this can vary from: – 1.200 to 1.500 mm w.g.
for wall heating units, as they have limited head circulation pumps;
– 1.500 to 2.500 mm w.g.
for floor-standing boilers, heat exchangers or heat pumps.
MAXIMUM DESIGN TEMPERATURE This is the maximum temperature of the heating fluid circulating in the panels. Here, values should be used varying from: – 45 a 55°C with traditional boilers; – 40 a 45°C with district heating, condensing boilers, heat pumps; – 32 a 38°C with solar panels. These values make it possible to obtain a good compromise between two different requirements: •
restricting the length (and thus the cost) of the panels,
•
optimising the efficiency of the heat source.
It is thus considered that low temperature heating is possible only with floors of limited thermal resistance (see sub-chapter THERMAL RESISTANCE OF FLOOR). It is advisable that the maximum design temperature should not exceed 55°C in order to avoid: •
creep in tiled floors;
•
cracking in parquet floors;
•
subsidence of floorings made or rubber or other synthetic materials;
•
“wave” floor temperatures, i.e. with considerable variations of hot zones and cold zones.
52
HEAT OUTPUT REQUIRED This is the output required from the panel to handle the thermal requirement of the room to be heated. This requirement must be calculated taking into consideration two typical aspects of rooms heated with panel systems: • the lack of heat loss through the floors, • the heat contribution of any panels located on the floor above.
AMBIENT TEMPERATURE This is the air temperature to be achieved within the room. Its value is generally imposed by law or by contractual clauses. Given equal ambient temperatures, it is considered that in a room heated with panels, the operating temperature (i.e. the temperature which will give a good approximation to heat comfort in the room) is on average 1÷1,5°C higher than that which can be obtained by heating with heat emitters (see Item GENERAL NOTES, sub-clause ENERGY SAVING).
53
TEMPERATURE OF THE ROOM OR GROUND BELOW This is the temperature of the room or ground below the structure containing the panels. To determine this, two situations must be considered: 1. room located under the slab containing the panels: its temperature is determined by the same criteria used for calculating heat losses. 2. ground under the slab containing the panels: its temperature can be determined by means of the following table:
TAB. 1 - Average temperature of the ground in relation to the outside temperature Outside
Average temperature
temperature
of ground under floor
- 20°C - 15°C - 10°C - 5°C 0°C + 5°C
+ 3°C + 5°C + 8°C + 10°C + 11°C + 12°C
54
THERMAL RESISTANCE OF FLOOR This is calculated using the formula: sp R p = ——— λp
where: R p sp λp
(3)
= thermal resistance of the floor, m2K/W = thickness of floor, m = thermal conductivity of floor, W/mK
Table (2) shows the thermal conductivity of materials used for making floor finishes.
TAB. 2 - Conductivity of materials used for flooring Material
Conductivity
W/mK Ceramic Brick Rubber Granite Linoleum Marble Carpet Parquet PVC flooring
1,00 0,90 0,28 3,20 0,18 3,40 0,09 0,20 0,23
The following tables contain pre-calculated values of the thermal resistance R p of flooring in ceramic, brick, rubber, marble and parquet.
55
Table (3) shows the indicative values of the maximum specific heat output which can be transferred by a panel, in relation to two variables; the thermal resistance of the floor and the maximum design temperature. These values (averagely valid for temperature differences of 8-12°C and for plastic pipes of outer diameter between 20 and 16 mm) can be used to determine (always with a certain degree of approximation): 1. the heat output of a panel when the floor type is varied; 2. the maximum design temperature in relation to the specific output requested and the thermal resistance of the floors used.
TAB. 3: Indicative values of the maximum specific heat output [W/m2]
which can be transferred by a panel Maximum Design Temperature, °C
Rp m K/W 2
30
32
34
36
38
40
42
44
46
48
50
0,000
48
58
68
79
89
99
109
119
130
140
150
0,010
45
54
64
74
83
93
102
112
121
131
141
0,020
42
51
60
69
78
87
96
105
114
124
133
0,030
40
48
57
66
74
83
91
100
108
117
126
0,040
38
46
54
62
70
79
87
95
103
111
119
0,050
36
44
52
59
67
75
83
90
98
106
114
0,060
34
42
49
57
64
72
79
86
94
101
109
0,070
33
40
47
54
61
68
76
83
90
97
104
0,080
31
38
45
52
59
66
73
79
86
93
100
0,090
30
37
43
50
57
63
70
76
83
90
96
0,100
29
35
42
48
55
61
67
74
80
87
93
0,110
28
34
40
46
53
59
65
71
77
83
90
0,120
27
33
39
45
51
57
63
68
74
80
86
0,130
26
32
37
43
49
55
60
66
72
78
83
0,140
25
31
36
42
47
53
58
64
70
75
81
0,150
24
30
35
40
46
51
57
62
67
73
78
56
CERAMIC TAB. 4 - Value of R p for λ p = 1,00 W/mK
s
Rp
6
0,006
8
0,008
10
0,010
12
0,012
BRICK TAB. 5 - Value of R p for λ p = 0,90 W/mK
s
Rp
10
0,011
15
0,017
20
0,022
30
0,033
RUBBER TAB. 6 - Value of R p for λ p = 0,28 W/mK
s
Rp
2
0,007
3
0,011
4
0,014
5
0,018
57
MARBLE TAB. 7 - Value of R p for λ p = 3,40 W/mK
s
Rp
10
0,003
15
0,004
20
0,006
30
0,009
PARQUET TAB. 8 - Value of R p for λ p = 0,20 W/mK
s
Rp
6
0,030
8
0,040
10
0,050
12
0,060
14
0,070
16
0,080
18
0,090
20
0,100
Table symbols: R p = thermal resistance of floor, m2K/W s = thickness of floor, mm λ p = thermal conductivity of floor, W/mK
58
THERMAL RESISTANCE UNDER PANEL This is the thermal resistance of the structure below the top level of the pipes and the surrounding environment
This is calculated using the formula: sd s is s in 1 R s = —— + —— + R sl + —— + —— λm λ is λ in α
given:
α
and where: R s
= 5,9 W/m2K = thermal resistance under panel, m2 K/W
s d = distance between upper level of pipes and insulation, m λ m = thermal conductivity of the slab, W/mK s is λ is
= thickness of insulating material, m = thermal conductivity of insulating material, W/mK
R sl = thermal resistance of floor slab, m2K/W s in = thickness of plaster, m λ in = thermal conductivity of plaster, W/mK
(4)
59
Table (9) shows the conductivity and thermal resistance of materials commonly located under the panels.
TAB. 9 - Conductivity or thermal resistance of materials located under panels Conductivity
Material
W/mK
Expanded clay Concrete Fibreglass Plaster with lime and gypsum Plaster with lime mortar Polystyrene Polyurethane Brick floor slab:
Boards:
Thermal resistance m2K/W
0,100 1,300 0,040 0,700 0,900 0,035 0,028
20 cm
0,32
24 cm
0,35
28 cm
0,37
15 cm
0,36
20 cm
0,40
25 cm
0,43
Cork sheets Expanded cork with binders Expanded vermiculite
0,040 0,045 0,070
The following pages contain tables with precalculated values of thermal resistance Rs for floor slab in brick, boards and floors on the ground.
60
FLOOR SLABS OF BRICK WITH POLYSTYRENE INSULATION
FLOOR SLABS OF BOARDS WITH POLYSTYRENE INSULATION
TAB. 10 - R s as function of h e s
TAB. 11 - R s as function of h e s
h
20
24
28
s
Rs
2,0
h
s
Rs
1,061
2,0
1,101
2,5
1,204
2,5
1,244
3,0
1,347
3,0
1,387
3,5
1,490
3,5
1,530
4,0
1,633
4,0
1,673
4,5
1,776
4,5
1,816
5,0
1,919
5,0
1,959
2,0
1,091
2,0
1,141
2,5
1,234
2,5
1,284
3,0
1,377
3,0
1,427
3,5
1,520
3,5
1,570
4,0
1,663
4,0
1,713
4,5
1,806
4,5
1,856
5,0
1,949
5,0
1,999
2,0
1,111
2,0
1,171
2,5
1,254
2,5
1,314
3,0
1,397
3,0
1,457
3,5
1,540
3,5
1,600
4,0
1,683
4,0
1,743
4,5
1,826
4,5
1,886
5,0
1,969
5,0
2,029
15
20
25
Symbols, tables 10 and 11: R s = thermal resistance under panel, m2K/W s = thickness of insulating material, cm h = height of floor slab, cm
61
FLOOR ON THE GROUND WITH POLYSTYRENE INSULATION TAB. 12 - R s as function of h e s
h
8 ÷ 12
s
Rs
2,0
0,687
2,5
0,830
3,0
0,973
3,5
1,115
4,0
1,258
4,5
1,401
5,0
1,544
Symbols, table 12: R s = thermal resistance under panel, m2K/W s = thickness of insulating material, cm h = thickness of concrete slab, cm
62
PARAMETERS TO BE DETERMINED For the correct and complete dimensioning of a panel, it is necessary to determine the following parameters:
surface temperature of floor; temperature difference of heating fluid; flow in panel; head required; lenght of panel; fluid velocity; total heat output emitted by panel; heat output emitted downwards; mean heat output emitted upwards by one metre of pipe; mean heat output emitted downwards by one metre pipe.
SURFACE TEMPERATURE OF THE FLOOR This is calculated using the following formula:
tp = ta +
(
q —— 8,92
)
1 1,1
(5)
where: t p = surface temperature of floor, °C t a = ambient temperature, °C q = specific heat output (upwards) of panel, W/m2 To avoid uncomfortable physiological conditions, the surface temperature of the floor should be less than: • • •
29°C in continuously occupied environments, 33°C in bathrooms, showers and swimming pools, 35°C in perimeter areas or rooms rarely used.
In order to comply with such values, precise limits of the heat output which can be transferred by a panel are required.
63
In particular (at ambient temperature = 20°C), the maximum specific output which can be transferred by a panel is: •
q max = 8,92 . ( 29 – 20 ) 1,1 = 100 W/m2
in continuously inhabited environments.
•
q max = 8,92 . ( 33 – 20 ) 1,1 = 150 W/m2
in bathrooms, showers and swimming pools.
•
q max = 8,92 . ( 35 – 20 ) 1,1 = 175 W/m2
in perimeter areas or rooms rarely used.
Multiplying the value of q max by the area of the panel gives the maximum heat output which the panel can transfer to the environment without causing a feeling of discomfort (see item DIMENSIONING OF PANELS , sub-chapter CALCULATION OF PANELS).
64
TEMPERATURE DIFFERENCE OF HEATING FLUID This is given by the difference between the flow and return temperatures of the heating fluid. It is advisable for its value not to be too high in order: •
not to over-reduce the average temperature of the fluid, and thus the heat output of the panel;
•
to avoid surface temperatures which differ too much from each other, especially with coil panels;
Usually it is advisable to adopt temperature differences below 8 ÷ 10°C.
PANEL FLOW This is calculated using the formula (13) given in the item FLOW OF HEAT FROM A PANEL. Considering that the maximum flow of a panel is on average between: – 200 ÷ 220 l/h, for pipes with D i = 16 mm – 120 ÷ 130 l/h, for pipes with D i = 13 mm it is possible to determine (although approximately) the maximum heat output (Q G. max) which a panel can transfer in relation to its internal diameter. In particular, considering a temperature difference of 8°C, this gives: •
Q G. max = ( 200 ÷ 220 ) . 8 . 1,16 = 1.856 ÷ 2.042 W
•
Q G. max = ( 120 ÷ 130 ) . 8 . 1,16 = 1.114 ÷ 1.206 W for D i = 13 mm
for D i = 16 mm
These values can be used as guidance parameters for establishing (as a first approximation) whether a room needs one or more panels.
65
HEAD REQUIRED This is calculated as shown in the chapter CALCULATION OF PANELS and must not exceed the preset head. The difference between these two heads is offset by the panel micrometric regulating valve.
It is advisable that the difference between the preset head and that required (i.e. the value of the offsetting by adjustment) should be at least 200 ÷ 300 mm w.g. It is thus possible (by opening the micrometric valve) to increase the flow through the panel and thus its heat output when the operating conditions are more demanding than those considered, for example when carpets, which were not provided for, are laid over the flooring, covering large areas.
LENGTH OF THE PANEL This is calculated using the formula (2) given in the item FLOW OF HEAT FROM A PANEL. There are no particular limits with regard to this value. In domestic applications, however, it is advisable not to go beyond the commercial lengths of pipe rolls (120 ÷ 150 metres).
66
FLUID VELOCITY It is advisable not to accept solutions where the fluid velocity is too low, essentially for two reasons: (1) to prevent the formation of air bubbles; (2) to prevent the flow of liquid from becoming laminar, as the panel emission formulae are only valid for turbulent flow. Normally, velocities higher than 0,1 m/s are acceptable. Higher velocities must be provided for when panels are made with reverse gradients (see 1st Handbook, VELOCITY OF FLUID).
TOTAL HEAT OUTPUT EMITTED BY A PANEL This is calculated using the formula (12) given in the item FLOW OF HEAT FROM A PANEL. It is used to determine the heat output which must be supplied by the heat generator.
HEAT OUTPUT EMITTED DOWNWARDS This is determined by the difference between the total heat output and that transferred upwards by the panel. It is used to determine the actual thermal requirement of the environment situated under the panel.
MEAN HEAT OUTPUT EMITTED UPWARDS FROM ONE METRE OF PIPE This is calculated by dividing the heat output transmitted upwards by the panel by its length. It is used to determine the heat contribution of the exposed pipes to the rooms crossed by them.
MEAN HEAT OUTPUT EMITTED DOWNWARDS FROM ONE METRE OF PIPE This is calculated by dividing the heat output transmitted downwards by the panel by its length. It is used to determine the heat contribution of the exposed pipes to the rooms underneath.
PROGRAMME FOR THE DIMENSIONING OF SYSTEMS WITH PANELS
PRINTER CONFIGURATION
MATERIALS ARCHIVES
GENERAL DATA ARCHIVES
MANAGEMENT OF PROJECT ARCHIVES
CALCULATION PROGRAMME
68
P R I N T E R C O N F I G U R AT I O N
This option allows you to set the top and left hand margins of the page layout. It also allows you to carry out a printing test. – Variable data: • top margin (in lines) • left hand margin (in characters) – Fixed data: • maximum number of characters per line = 66 • maximum number of lines per page = 58 There are three commands managing the inputting of the printed page: F1
Saves without printing test
F2
Saves with printing test
ESC Exits without saving
69
M AT E R I A L S A R C H I V E S
ARCHIVE OF ZONE VALVES
2-way valves 3-way valves
ARCHIVE OF VALVES FOR HEAT EMITTERS
normal valves valves with thermostatic option thermostatic valves thermoelectric valves lock shield valves
HEAT EMITTERS ARCHIVE
modular radiators non-modular radiators convectors fan coils
70
ZONE VALVE ARCHIVE Allows you to store and up-date (in groups of the same commercial series) the main characteristics of the zone valves. Archive capacity: 20 groups. The zone valve archive is also used by the programme for dimensioning systems with manifolds.
ELEMENTS OF THE ARCHIVE
n
Archive number (storage code) - maximum value accepted: 20.
c
Zone valve type: - 2-way valves, - 3-way valves.
Brand name
Brand names of valves - available space 11 characters.
model
Valve group model - available space 14 characters.
KV0,01 (3/4”)
Nominal flow rate of valve with Dn = 3/4”, l/h - maximum value accepted: 9999 l/h. - whole numbers only shown on screen.
KV0,01 ( 1” )
Nominal flow rate of valve with Dn = 1”, l/h - maximum value accepted: 9999 l/h. - whole numbers only shown on screen.
71
COMMAND FUNCTIONS
The zone valves archive can be managed by means of the following command functions:
Scroll
Enables vertical scrolling on screen.
F1
New valve group
Inserts a new valve group.
F2
Modify
Modifies the elements of the valve group except the valve type.
F3
Cancel
Cancels a valve group.
F5
Go to ...
Displays a specific group of valves.
F6
Print
Prints the valves in the archive.
F7
Save
Saves the up-dates of the archive.
ESC Exit without saving
Exits from the archive without saving.
72
ARCHIVE OF VALVES FOR HEAT EMITTERS Allows you to store and up-date (in groups of the same commercial series) the main characteristics of the valves for heat emitters. Archive capacity: 50 groups The valves archive is also used by the programme for dimensioning systems with manifolds.
ELEMENTS OF THE ARCHIVE
n
Archive number (storage code) - maximum value accepted: 50.
c
Valve types: - 1 normal valves, - 2 valves with thermostatic option - 3 thermostatic valves, - 4 thermoelectric valves, - 5 lock shield valves.
Brand name
Brand names of valves - available space 11 characters.
Model
Valve group model - available space 11 characters.
KV0,01 (3/8”)
Nominal flow rate of valve with Dn = 3/8”, l/h - maximum value accepted: 9999 l/h. - whole numbers only shown on screen.
KV0,01 (1/2”)
Nominal flow rate of valve with Dn = 1/2”, l/h - maximum value accepted: 9999 l/h. - whole numbers only shown on screen.
73
COMMAND FUNCTIONS
The valves for heat emitters archive can be managed by means of the following command functions:
Scroll
Enables vertical scrolling
F1
New valve group
Inserts a new group of valves.
F2
Modify
F3
Cancel
Cancels a group of valves.
F5
Go to ...
Displays a specific group of valves.
F6
Print
Prints the valves in the archive.
F7
Save
Saves the up-dates of the archive.
ESC Exit without saving
Modifies the elements of the group of valves
except for the relevant types.
Exits from the archive without saving.
74
HEAT EMITTERS ARCHIVE Allows you to store and up-date the main characteristics of radiators, convectors and fan coils. Archive capacity: 200 heat emitters.
N.B.: This archive is also used by the programme for dimensioning systems with manifolds and makes it possible to store three types of heat emitter - radiators; - convectors; - fan coils. Only radiators are already recognised and used by the programme for the dimensioning of panels. All the archive elements are presented below, including those for convectors and fan coils.
ELEMENTS OF THE ARCHIVE
n
Archive number (storage code) - maximum value accepted: 200.
c
Heat emitter types:
-1 -2 -3 -4 Brand name Model
modular radiators, non-modular radiators, convectors, fan coils.
Brand names of heat emitters - available space 12 characters. Heat emitter model
- available space 8 characters.
75
tm
Mean temperature of heating fluid, °C - max. accepted value: 99 °C.
- whole numbers only shown on screen. Qn (*)
Nominal heat output, W
- max. accepted value: 9999 W. - whole numbers only shown on screen. l
Width of heat emitter, mm - size required only for non-modular heat emitters. - max. accepted value: 9999 mm. - whole numbers only shown on screen.
m
Width of boss, mm
- size required only for modular heat emitters. - max. accepted value: 999 mm. - whole numbers only shown on screen. h
Height of heat emitter, mm
- max. accepted value: 9999 mm. - whole numbers only shown on screen. Gn (*)
Nominal flow rate of heat emitter, l/h
- required only for convectors and fan coils. - max. accepted value: 9999 l/h. - whole numbers only shown on screen. Hn (*)
Heat emitter pressure differential, mm w.g.
- size required only for convectors and fan convectors. - max. accepted value: 9999 mm w.g. - whole numbers only shown on screen. vol
Water contained by basic element (modular heat emitters) or by
the heat emitter (non modular heat emitters), l - max. accepted value: 99,99 l. - value shown on screen to 2 decimal places.
(*)
Definitions of Qn, Gn, Hn Qn Nominal heat output: this is the heat output which the heat emitter ex-
changes with the external environment in test conditions Gn Nominal flow rate: this is the flow rate required to determine the nomi-
nal heat output of the heat emitter. Hn Nominal pressure differential: this is the differential pressure required
to pass the nominal flow rate through the heat emitter.
76
COMMAND FUNCTIONS
The heat emitters archive can be managed by means of the following command functions:
Scroll
Enables vertical scrolling.
F1
New heat emitter
Inserts a new heat emitter.
F2
Modify
F3
Cancel
Cancels a group of heat emitters.
F5
Go to ...
Displays a specific group of heat emitters.
F6
Print
Prints the heat emitters in the archive.
F7
Save
Saves the up-dates of the archive.
ESC Exit without saving
Modifies the elements of the group of heat
emitters except for the relevant types.
Exits from the archive without saving.
77
G E N E R A L D ATA A R C H I V E S
DATA ANALYSIS
MAIN PARAMETERS ARCHIVE GRAPHICAL REPRESENTATION
DATA ANALYSIS
MANIFOLD CHARACTERISTICS ARCHIVE GRAPHICAL REPRESENTATION
DATA ANALYSIS
PIPES AND CENTRE DISTANCE ARCHIVE GRAPHICAL REPRESENTATION
78
MAIN PARAMETERS ARCHIVE This makes it possible to predetermine the following parameters to be proposed as default for the dimensioning of the system: 1. Preset head to panel
- values accepted from 500 to 5000 mm w.g. - whole numbers only shown on screen. 2. Project maximum temperature - values accepted from 30 to 60°C.
- whole numbers only shown on screen. 3. Ambient temperature - values accepted from 10 to 25°C.
- whole numbers only shown on screen. 4. Zone valve group code - values accepted from 0 to 20. 5. Underlying ground or room temperature - values accepted from -15 to 20°C.
- whole numbers only shown on screen. 6. Thermal resistance of floor - values accepted from 0,000 to 0,150 m2K/W. - values shown on screen to 3 decimal places. 7. Thickness of slab
- values accepted from 2 to 20 cm. - whole numbers only shown on screen. 8. Thermal resistance under panel - values accepted from 0,500 to 3,500 m2K/W. - values shown on screen to 3 decimal places. 9. Minimum velocity of fluid in panels - values accepted from 0,05 to 0,40 m/s. - values shown on screen to 2 decimal spaces. 10. Valves for heat emitters group code - values accepted from 1 a 50. 11. Lockshield group code - values accepted from 1 to 50. 12. Reference heat emitter code - values accepted from 0 to 200. 13. Temperature difference of heat emitter - values accepted from 2 to 10°C.
- whole numbers only shown on screen. 14. Maximum velocity of carrying fluid in heat emitter pipes - values accepted from 0,5 to 1,5 m/s. - values shown on screen to 2 decimal spaces.
79
80
MANIFOLD DATA ARCHIVE This makes it possible to predetermine the main characteristics of the manifold and the relative on-off and regulating valves. 1.
Brand name of manifold - available space 10 characters.
2.
Manifold identifying symbol - available space 10 characters.
3.
Internal diameter of manifold - values accepted from 20 to 60 mm. - values shown on screen to 1 decimal place.
4.
KV0,01 panel manual on-off valve - maximum value accepted 9999 l/h.
- whole numbers only shown on screen. 5.
KV0,01 panel automatic on-off valve - maximum value accepted 9999 l/h.
- whole numbers only shown on screen. 6.
Type of on-off valve proposed: - 1 manual, - 2 automatic.
7.
KV0,01 micrometer regulating valve - maximum value accepted 999,9 l/h. - values shown on screen to 1 decimal place.
81
DATA ARCHIVE FOR PIPES AND CENTRE DISTANCES This makes it possible to predetermine the main characteristics of the pipes and the possible fitting centre distances. 1.
Brand name of pipe - available space 10 characters.
2.
Pipe material code: 1 PEX - 2 PB - 3 PP
3.
External diameter of pipe for panels - values accepted from 15 to 22 mm. - values shown on screen to 1 decimal place.
4.
Internal diameter of pipe for panels - values accepted from 10 to 18 mm. - values shown on screen to 1 decimal place.
5.
External diameter of pipe for heat emitters - values accepted from 12 to 20 mm. - values shown on screen to 1 decimal place.
6.
Internal diameter of pipe for heat emitters - values accepted from 8 to 16 mm. - values shown on screen to 1 decimal place.
7.
Grid of available centre distances - values accepted from 7,5 to 40 mm. - values shown on screen to 1 decimal place.
N.B.: The grid must be supplemented with the entry (from the smallest centre distance) of the five centre distances provided for. For this purpose, the support values can also be entered, thus avoiding accepting the relative solutions.
82
PROJECT ARCHIVE MANAGEMENT
This part of the programme makes it possible to store and recall the data (files) for each project processed. The files are saved in a suitable directory and can be opened or recalled with the options specified below.
CHARACTERISTICS OF THE ARCHIVE CONTAINING THE PROJECT FILES
• Resides on floppy disk to be inserted in drive A. • Initialised by programme with suitable procedure. • Maximum capacity 70 projects (actual capacity depends on capacity of floppy disk and size of project files).
MAIN OPTIONS FOR FILE MANAGEMENT N
New
• Opens a new project file on the floppy archive. • Stores the principal recognition data and location of system. • Checks general data archives. • Starts up calculation programme.
V
Old
• Calls up an existing project file on floppy. • Checks and corrects the client's recognition data and system location. • Starts up calculation programme, indicating last manifold calculated.
E
Delete
• Deletes a project file.
83
C A L C U L AT I O N P R O G R A M M E
First Part MANIFOLD MANAGEMENT AND PROCESS PRINTING
Provides:
manifold dimensioning start-up, general data archive check, modification of main parameters, examination of data on each manifold, modification of data on each manifold, print out of accepted solutions, print out of materials calculation.
Second part MANAGEMENT OF BRANCH CIRCUITS
Provides:
dimensioning of branch circuits, modification of branch circuit data, examination of data and solutions accepted, storage of solutions accepted.
Third part SELECTION OF SOLUTIONS PREPARED
For each branch circuit, provides:
acceptance of required solution, variation of project data, request for new dimensioning.
84
MANIFOLD MANAGEMENT AND PROCESS PRINTING The following command functions are available for this first part of the programme:
N
New manifold
Dimensions a new manifold.
E
Examine manifold
Examines the data (project and calculation) relating to a specific manifold.
M
Modify manifold
Modifies the project data or accepted solutions for the branch circuits relating to a specific manifold.
F1
General data - Checks the data of the general archives. - Also varies the data of the main parameters. However, it is not possible (once the project has started) to vary the data on manifold, pipes and centre distances.
F6
Print project Prints the solutions accepted and the metric calculation.
F10 End of task
Exits from calculation programme.
85
MANAGEMENT OF BRANCH CIRCUITS The following command functions are available for this part of the programme:
P
Panel
Dimensions a panel.
R
Heat emitter Dimensions a heat emitter and the relevant circuit.
E
Examination of data not on screen
Examines the data (for the panels or heat emitters) not normally shown on screen.
M
Modifies project data
Varies project data of branch circuits.
C
Cancels panel/heat emitter
Cancels a panel or heat emitter.
Esc
Exits
Abandons dimensioning the manifold.
F10 End of calculation
– Stores the solutions relating to the circuits dimensioned (on the project files). – Also stores these solutions several times so that the materials in the system with equal branches can be calculated more easily: for example in multi-storey buildings or detached houses.
86
PANEL DIMENSIONING This is done in three stages: – project data acquisition, – development of calculations, – presentation of data processed.
ACQUISITION OF PROJECT DATA
The project data required can be broken down into two groups: – data requested by programme: - data relating to the manifold, - data relating to the panel. – data derived from the archives.
Data required relating to the manifold Used to define the conditions on the basis of which the manifold feeds its branches (panels or heat emitters). Data required: Hpann (*)
Preset head on panel - values accepted from 500 to 5000 mm w.g. - whole numbers only shown on screen.
tmax (*)
Maximum project temperature - values accepted from 30 to 60°C. - whole numbers only shown on screen.
cvz (*)
Zone valve group code - values accepted from 0 to 20. - for manifolds with no zone valve, put cvz=0.
N.B. This data is only required when dimensioning of a new manifold is started.
(*)
Data proposed as default on the basis of the predefined general parameters.
87
Data required regarding the panel Used to identify the geometrical characteristics of the panel and the conditions on the basis of which it must be dimensioned. Data required: Room
Purpose of the room used - available space 12 characters.
Q
Heat output required - maximum value accepted 9999 W. - whole numbers only shown on screen.
S
Total area of panel (including peripheral zone) - maximum value accepted 99,9 m2. - value shown on screen to 1 decimal place.
Szp (1)
Area of peripheral zone - maximum value accepted 9,9 m2. - value shown on screen to 1 decimal place.
La
Length of manifold-panel piping - maximum value accepted 99 m. - whole numbers only shown on screen.
ta (*)
Ambient temperature - values accepted 10 to 25°C. - whole numbers only shown on screen.
Rp (*)
Thermal resistance of floor - values accepted from 0,000 to 0,150 m2K/W. - value shown on screen to 3 decimal places.
sm (*)
Thickness of slab - values accepted from 2 to 20 cm. - whole numbers only shown on screen.
Rs (*)
Thermal resistance under panel - values accepted from 0,500 to 3,500 m2K/W. - value shown on screen to 3 decimal places.
vi (*)
Proposed on-off valves - values accepted: 1 and 2.
N.B.(1): The value of Szp (peripheral zone area) cannot be greater than 40% of S (total panel area). (*)
Data proposed as default on the basis of the predefined general parameters.
88
DEVELOPMENT OF CALCULATIONS Having acquired the project data, the programme prepares the solutions relating to each centre distance of the available grid (see PIPES AND CENTRE DISTANCES ARCHIVE) and breaks down these solutions into two categories: acceptable and unacceptable.
Acceptable solutions The programme accepts all solutions where the cases specified below do not arise.
Unacceptable solutions The programme does not accept the solutions where at least one of the following conditions arises: – Q max (I) ‹ Q The maximum heat output which can be transferred by the panel (in relation to the centre distance in question) is not able to handle the output required: this means that the panel is under-dimensioned (see DIMENSIONING OF PANELS) (-) is the symbol on screen showing unacceptability. – Q min (I) › Q The minimum heat output which can be transferred by the panel (in relation to the centre distance in question) is too high in relation to the output required; this means that the panel is over-dimensioned (see DIMENSIONING OF PANELS). (+) is the symbol on screen showing unacceptability. – H (I) › H pann The head required (in relation to the centre distance considered) is too high in relation to that pre-set (see DIMENSIONING OF PANELS). (H) is the symbol on screen showing unacceptability.
89
PRESENTATION OF THE DATA PROCESSED For each centre distance available, the programme presents the solutions prepared on screen and (where acceptable) the following sizes: tp
Surface temperature of floor
tzp
Surface temperature of peripheral zone
dt
Temperature difference between fluid inlet and outlet temperatures
L
Total length of pipe
v
Velocity of fluid
In addition, the programme indicates, in flashing characters, cases where the velocity of the fluid is lower than the limit defined in the GENERAL PARAMETERS ARCHIVE. The main commands for selecting the proposed solutions are shown in the chapter “SELECTION OF THE SOLUTIONS PROCESSED”.
90
CALCULATION OF HEAT EMITTERS This is carried out in three stages: – acquisition of project data, – development of calculations, – presentation of data processed.
ACQUISITION OF PROJECT DATA
The project data required can be broken down into two groups: – data requested by the programme: - data regarding the manifold, - data regarding the heat emitters. – data derived from the archives.
Data requested regarding the manifold This is used to define the conditions on the basis of which the manifold feeds its branches and are the same required for the dimensioning of the panels.
Data requested regarding the heat emitter Used to identify the type of heat emitter and the conditions on the basis of which it must be dimensioned. Data requested: Room
Purpose of room served - available space 12 characters.
Q
Heat output required - maximum value accepted 9999 W. - whole numbers only shown on screen.
91
La
Length of manifold-heat emitter pipes - maximum value accepted 99 m. - whole numbers only shown on screen.
r (*)
Heat emitter code - values accepted from 1 to 200.
ta (*)
Ambient temperature - values accepted from 10 to 25°C. - whole numbers only shown on screen.
dt (*)
Temperature difference input - values accepted from 1 to 20°C. - whole numbers only shown on screen.
cv (*)
Code of valve group for heat emitters - values accepted from 1 to 50.
cd (*)
Code of lock shield valve group for heat emitters - values accepted from 1 to 50.
vi (*)
Proposed on-off valves: - values accepted: 1 and 2.
DEVELOPMENT OF CALCULATIONS
When the project data is acquired, the programme prepares the requested solution on the basis of the temperature difference input and considers these solutions acceptable only if a head lower than that available at the manifold connections is requested. If the head is too high, the temperature difference input must be increased. In this way the flow through the heat emitter, and thus the requested relative head, is reduced.
PRESENTATION OF THE DATA PROCESSED
The programme presents the solution processed on screen and indicates in flashing characters cases where the fluid velocity is above the limit defined in the GENERAL PARAMETERS ARCHIVE. The main commands permitting acceptance or revision of the proposed solution are given in the following chapter.
(*)
Data proposed as default on the basis of the predefined general parameters.
92
SELECTION OF THE SOLUTIONS PROCESSED The following command functions are available for selection of the solutions processed:
1÷5
Solutions to be accepted
This function is reserved for the panels and makes it possible (within the scope of the possible solutions) to select the panel configuration considered most appropriate.
Exec
Accepts
This function is reserved for the heat emitters and makes it possible to accept the proposed solution.
V
Vary data
Makes it possible to vary the project data and carry out new dimensioning (for both panels and heat emitters).
Esc
Exits without saving
Cancels all data of the branch circuit in question and permits dimensioning from zero.
EXAMPLE OF CALCULATION
94 Example: Dimension a panel system for zone heating of dwellings represented in the page alongside. The following are considered: – ta = 20°C ambient temperature – ts =
5°C temperature of basement
– heating requirement: Room
n
- living - kitchen - bathroom A - bedroom A - bedroom B - bathroom B - corridor
1 2 3 4 5 6 7
2nd floor W 2.900 1.180 610 1.430 1.050 310 180
1st floor W 2.420 990 520 1.150 770 250 90
mezzanine W 2.420 990 520 1.150 770 250 90
N.B.: for rooms in the mezzanine, the heat losses of floor have not been taken into consideration (see sub-chapter under DIMENSIONING OF PANELS). – structure of floor slabs: - ceramic, - slab, - polystyrene insulation, - brick floor slab, - plaster,
s = 0,8 cm s = 8,0 cm ..................... thickness to be defined s = 20,0 cm s = 1,5 cm
Solution: The Caleffi Handbooks 99 software is used, and on the basis of this configuration, the system is broken down dimensionally into the following phases: – Analysis and selection of data regarding the main parameters archive – Selection of manifold and valves for control and regulation of panels – Selection of pipes and available centre-to-centre distances – Notes and conventions assumed – Activation of project file – Dimensioning of branches and manifolds on 2nd floor – Dimensioning of branches and manifolds on 1st floor – Dimensioning of branches and manifolds on mezzanine – Printing calculation and symbols – Dimensioning distribution network – Calculation of total heat output
95
96 Analysis and selection of data relating to the main parameters archive
– Preset head at panel connections The main system network is dimensioned by the practical calculation method illustrated under SIMPLE CIRCUITS, 2nd Handbook.
On the basis of this method (the variation in head from floor to floor is considered on average to be 100 mm w.g.) and in relation to the terms of the item DIMENSIONING THE PANELS (subchapter PRESET HEAD), the following is assumed: H pann = 1.800 mm w.g. (2nd floor) H pann = 1.900 mm w.g. (1st floor) H pann = 2.000 mm w.g. (mezzanine)
97 – Thermal resistance of floor This can be calculated using formula (3) or the tables given under DIMENSIONING OF PANELS, sub-chapter THERMAL RESISTANCE OF FLOOR. The table on ceramics, for a thickness of 0.8 cm, gives: R p = 0,008 m2K/W.
– Maximum design temperature This is determined using Table 3 given under the item DIMENSIONING OF PANELS, sub-chapter THERMAL RESISTANCE OF FLOOR. On the basis of this table: - where: R p = 0,008 m2K/W, - considering values of q max not greater than 95÷100 W/m2, - also considering that a low design temperature makes it possible to use a condensing boiler or heat pump also, it is assumed that : t max = 40°C.
– Zone valves Caleffi model 6480/6460 3-way zone valves are used with the following characteristics: - 3/4” valve KV0,01 = 1.200 l/h - 1” valve KV0,01 = 3.000 l/h These valves are already on file with the code number: cvz = 1.
– Thickness of the slab above the pipes This is obtained by subtracting the outer diameter of the pipes from the thickness of the slab. In the case in question, considering pipes of outer diameter 2 cm and slab thickness 8 cm, the following is obtained: s = 8,0 - 2,0 = 6,0 cm.
– Thermal resistance under panel To limit the heat output transferred downwards by the panels from the mezzanine and from the 2nd floor panels (the latter are the panels which have to produce the greatest heat output) the following thicknesses of insulating material are assumed: - 2nd floor insulating material thickness = 4,0 cm - 1st floor insulating material thickness = 2,0 cm - mezzanine insulating material thickness = 4,0 cm
98
The thermal resistance under the panel can be calculated using the formula (4) or with the tables given under the heading DIMENSIONING OF PANELS, sub-chapter THERMAL RESISTANCE UNDER PANEL. In the case in question, from the table regarding brick floor slab and polystyrene insulation, for the thicknesses of insulation specified above, the following is obtained: R s = 1,633 m2K/W (2nd floor) R s = 1,061 m2K/W (1st floor) R s = 1,633 m2K/W (mezzanine)
– Minimum velocity of fluid in panels The following is taken (see relevant sub-chapter under the heading DIMENSIONING OF PANELS): v min = 0,05 m/s.
– Valves for heat emitters Caleffi model 338/sq valves with thermostatic option are used with the following characteristics: - 3/8” valve KV0,01 = 222 l/h - 1/2” valve KV0,01 = 270 l/h These valves are already on file with the code number cv = 2.
– Lock Shield Valves for heat emitters Caleffi model 342/sq lock shield valves are used with the following characteristics: - 3/8” valve KV0,01 = 242 l/h - 1/2” valve KV0,01 = 399 l/h These valves are already on file with the code number cd = 10.
– Reference heat emitter A radiator of the following characteristics is taken as the reference heat emitter (i.e. to be proposed as default): - trade name, - model, - mean test temperature, - rated heat output, - width, - height, - water content,
OMEGA
680/4 80°C 145 W 60 mm 680 mm 1,10 l
This heat emitter is already on file with the code number: r = 1.
99 – Temperature difference across heat emitter The default temperature difference for dimensioning the integrated heat emitters is:
∆ t = 4°C. This value generally provides a good compromise between two different requirements: (1) not to reduce the average temperature, and thus the output of the heat emitter excessively; (2) not to call for excessively high flows and thus heads greater than available.
– Maximum velocity of flow in the pipes of the heat emitters The following is taken (see relevant sub-chapter under the heading DIMENSIONING OF SYSTEMS WITH MANIFOLDS):
v max = 0,75 m/s
On the basis of the project data and the choices made, the following values are input in the GENERAL PARAMETERS file:
GENERAL PARAMETERS FILE
Preset head at panel [mm w.g.] ............................ 1800 Maximum design temperature [°C] ...................... 40 Ambient temperature [°C] ...................................
20
Zone valve group code .........................................
1
Ambient temperature below [°C] ......................... 20 2 Floor thermal resistance [m K/W] ....................... 0,008 Slab thickness above pipes [cm] ........................... 6 Thermal resistance under panels [m2K/W] .......... 1,633 Min. Vel. heating fluid (panels) [m/s] .................. 0,05 Heat emitters valve group code ............................ Lock shield valve group code ................................ Reference heat emitter code ................................. Project temperature difference (heat emitter) [°C] .... Min. Vel. heating fluid (heat emitter) [m/s]............
2 10 1 4 0,75
N.B.: The preset head, the temperature of the room below and the thermal resistance under the panel refer to the last floor, in other words the floor from which the dimensioning of the system starts.
100 Selection of manifold and valves for control and regulation of panels
The following are used: - flow manifold - return manifold
Caleffi model 666 with relevant micrometric regulating valves, Caleffi model 667 with relevant manual shut-off valves.
On the basis of the choices made (type of manifold and valves) the following values are input in the MANIFOLD CHARACTERISTICS archive:
MANIFOLD CHARACTERISTICS ARCHIVE
Trade name of manifold ................................ CALEFFI Identifying logo ............................................ 666/667 Internal diameter of manifold ............. [mm]
31,0
Panel manual shut-off valve KV [ 0,01 bar] .. Panel automatic control valve KV [ 0,01 bar] Types of control valve proposed: 1 manual, 2 automatic
287 287 1
Micrometric reg. Valve KV [ 0,01 bar]: ” ” ” ” : ” ” ” ” : ” ” ” ” : ” ” ” ” : ” ” ” ” : ” ” ” ” : ” ” ” ” : ” ” ” ” : ” ” ” ” :
curve ” ” ” ” ” ” ” ” ”
Selection of pipes and available centre-to-centre distances
– Pipes Pipes are used having the following characteristics: - trade name, - material,
SIGMA
PEX
- D e = 20 mm, D i = 16 mm, for making panels, - D e = 15 mm, D i = 10 mm, for connecting heat emitters.
1 6,0 2 18,0 3 21,0 4 27,0 5 31,0 6 42,0 7 53,0 8 70,0 9 89,0 10 115,0
101 – Grid of available centre-to-centre distances The following 5 centre-to-centre distances are used (see explanatory note in the item GENERAL DATA ARCHIVES, sub-chapter DATA ARCHIVES REGARDING PIPES AND CENTRE-TO-CENTRE DISTANCES): - 7,5 cm - 15,0 cm - 22,5 cm - 30,0 cm - 37,5 cm
On the basis of the selections made (type of pipes and grid of centre-to-centre distances) the following values are input in the PIPES AND CENTRE-TO-CENTRE DISTANCES archive.
PIPES AND CENTRE DISTANCES ARCHIVE
Pipe trade name ............................................ Material code (1 - PEX, 2 - PB, 3 - PP) ... External diameter pipe for panels Internal diameter pipe for panels
SIGMA 1
[mm] [mm]
20,0 16,0
External diameter pipe for heat emitters. [mm] Internal diameter pipe for heat emitters. [mm]
15,0 10,0
Grid of available centre to centre distances:
7,5 15,0 22,5 30,0 37,5
1st centre dist. [cm] 2nd centre dist. [cm] 3rd centre dist. [cm] 4th centre dist. [cm] 5th centre dist. [cm]
Notes and conventions assumed 1. The manifolds and branches are dimensioned starting from the last floor. This makes it possible: - to calculate the heat output transferred to the rooms of the underlying floor (see item DIMENSIONING OF PANELS, sub-chapter HEAT OUTPUT REQUIRED). - to check that the pre-set project temperature can provide the heat output required. The second and last storey is in fact thermally more demanding as it has a greater loss area and does not receive heat from the floor slab of the storey above. 2. The heating contribution of the panels placed on the upper storey is taken as half of that actually transferred. This procedure - combined with good insulation under the panels - guarantees valid thermal conditions even when the system in the rooms above is turned off.
102 3. The column and manifold positions shown below are used:
Activation of project file The project file is started up by inputting:
Project file name: Client name: Building location:
PAN-ES AA BB
103
Dimensioning of the branches and manifolds on 2nd floor The programme shows as general data for the first manifold: H pann = 1.800 mm w.g. 40°C cvz = 1
t max =
These values are accepted and the dimensioning is started from the first branch.
■
Living room, room No. 1, 2nd floor The high heat output required (2,900 W) means that two panels should be used (see item DIMENSIONING OF PANELS, sub-chapter PANEL FLOW). Therefore the following is proposed: Branch 1 - Living room 1A:
solutions relating to the data proposed:
Q = 2.900 / 2 = 1.450 W S = 34 / 2 = 17 m2 La = = 1m other data as proposed by the programme as default n
I
C
1 2 / / /
7,5 15,0 22,5 30,0 37,5
(-) (-) (-)
tp 27,8 27,8
tzp -
dt 10,5 6,0
L 228 114
v 0,18 0,32
Solution No. 2 is accepted. The same data is proposed and the same solution is also achieved for branch No. 2 - Living room 1B
■
Kitchen, room No. 2, 2nd floor The heat output required (1,180 W) and the available area (14 m2 ) are such that a single panel will be sufficient. Therefore the following is proposed: Branch 3 - Kitchen 2:
solutions relating to the data proposed:
Solution No. 2 is accepted.
Q = 1.180 W S = 14 m2 La = 8m other data as proposed by the programme as default n
I
C
1 2 / / /
7,5 15,0 22,5 30,0 37,5
(-) (-) (-)
tp 27,7 27,7
tzp -
dt 11,0 6,0
L 195 101
v 0,14 0,26
104
■
Bathroom, room No. 3, 2nd floor Considering a useful area of 3m2, the maximum heat output (Q max) which a panel can transfer to a bathroom is: Q max = q max . S = 150 . 3 = 450 W This output is lower than required (610 W) and an additional heat emitter must therefore be provided. For dimensioning the panel, it is assumed as an initial approximation that it can transfer its maximum output, so the following is proposed Branch 4 - Bathroom 3A:
Q = 450 W S = 3 m2 La = 5m other data as proposed by the programme as default
Processing this data does not give an acceptable solution. Therefore the panel is recalculated, reducing the output value required. For example, putting Q = 360 W makes solution No. 1 acceptable, in other words the solution which provides for a centre-to-centre distance of 7,5 cm. The following is proposed for dimensioning the heat emitter: Branch 5 - Bathroom 3B:
Q = 610 - 360 = 250 W La = 12 m other data as proposed by the programme as default
The solution prepared by the programme, which provides for a heat emitter consisting of 8 elements of model 680/4 (defined as default) is accepted
■
Bedroom, room No. 4, 2nd floor The heat output required (1,430W) and the available area (20 m2) mean that a single panel is sufficient. The following is therefore proposed Branch 6 - Kitchen 4:
solutions relating to the data proposed:
Solution No. 3 is accepted.
Q = 1.430 W S = 20 m2 La = 6m other data as proposed by the programme as default n
I
C
1 2 3 / /
7,5 15,0 22,5 30,0 37,5
(-) (-)
tp 26,6 26,6 26,6
tzp -
dt 14,0 10,5 5,5
L 273 139 95
v 0,13 0,18 0,34
105
■
Bedroom, room No. 5, 2nd floor The heat output required (1,050W) and the available area (20 m2) mean that a single panel is sufficient. The following is therefore proposed Branch 7 - Bedroom 5:
solutions relating to the data proposed:
Q = 1.050 W S = 20 m2 La = 8m other data as proposed by the programme as default n
I
C
1 2 3 4 /
7,5 15,0 22,5 30,0 37,5
(-)
tp 25,0 25,0 25,0 25,0
tzp -
dt 17,5 15,5 12,5 8,5
L 275 141 97 75
v 0,08 0,09 0,11 0,16
Solution No. 4 is accepted.
■
Bathroom room No. 6, 2nd floor The heat output required (310 W) and the available area (2.8 m2) mean that a single panel is sufficient. The following is therefore proposed Branch 8 - Bathroom 6:
solutions relating to the data proposed:
Q = 310 W S = 2,8 m2 La = 6m other data as proposed by the programme as default n
I
C
1 / / / /
7,5 15,0 22,5 30,0 37,5
(-) (-) (-) (-)
tp 29,9
tzp -
dt 3,5
L 43
v 0,12
Solution No. 1 is accepted
■
Corridor, room No. 7, 2nd floor The heat given off by the pipes leading to other panels is considered sufficient here.
The solutions prepared are accepted twice to confirm the calculation of the materials for both the dwellings on the second floor. A drawing follows, plus the print-outs which show the results obtained (see key to symbols used at the end of the panel dimensioning).
106
107
108
109
110
111
112 Dimensioning of the branches and manifolds on 1st floor For the GENERAL DATA function, enter:
H pann = 1.900 mm w.g. Rs = 1,061 m2K/W
(previous val. 1.800) (previous val. 1,633)
The dimensioning of the second manifold is then required, and, accepting the relevant data offered as default, the dimensioning of the branches is commenced.
■
Living room, room No. 1, 1st floor The high heat output required (2,900 W) means that two panels should be used (see item DIMENSIONING OF PANELS, sub-chapter PANEL FLOW). Therefore the following is proposed:
Branch 1 - Living room 1A:
Q = ( 2.420 / 2 ) - ( 134 / 2 ) = 1.143 W (1) S = 34 / 2 = 17 m2 La = = 1m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 3 is accepted (I = 22.5 cm). The same data is proposed and the same solution is also accepted for branch No. 2 - Living room 1 B.
■
Kitchen, room No. 2, 1st floor The heat output required and the available area are such that a single panel will be sufficient. Therefore the following is proposed: Branch 3 - Kitchen 2:
Q = 990 - ( 109 / 2 ) = 936 W (1) S = 14 m2 La = 8m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 3 is accepted (I = 22,5 cm).
■
Bathroom, room No. 3, 1st floor Same as for 2nd floor bathroom, dimensioning a panel with Q = 360 W and I = 7,5 cm. For dimensioning of the heat emitter, the following is proposed Branch 5 - Bathroom 3B:
Q = 520 - 360 - ( 33 / 2 ) = 144 W (1) La = 12 m other data as proposed by the programme as default
The solution proposed by the programme is accepted, which provides for a heat emitter consisting of 5 elements, model 680/4 (defined as default).
(1)
For the calculation of Q, see: Notes and conventions used.
113
■
Bedroom, room No. 4, 1st floor The heat output required and the available area mean that a single panel is sufficient. The following is therefore proposed: Branch 6 - Bedroom 4:
Q = 1.150 - ( 132 / 2 ) = 1.084 W (1) S = 20 m2 La = 6m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 4 is accepted. (I = 30,0 cm).
■
Bedroom, room No. 5, 1st floor The heat output required and the available area mean that a single panel is sufficient. The following is therefore proposed: Branch 7 - Bedroom 5:
Q = 770 - ( 97 / 2 ) = 722 W (1) S = 20 m2 La = 8m other data as proposed by the programme as default
Only Solution No. 5 was considered acceptable (I = 37.5 cm). However, it is advisable to adopt a smaller centre-to-centre distance (see item DIMENSIONING OF PANELS, sub-chapter CENTRE-TO-CENTRE DISTANCES). For this purpose, the surface (S) of the panel is reduced. In particular, S = 14 m2 and the new solution No. 4 (I = 30,0 cm) is accepted.
■
Bathroom, room No. 6, 1st Floor The heat output required and the available area mean that a single panel is sufficient. The following is therefore proposed: Branch 8 - Bathroom 6:
Q = 250 - ( 29 / 2 ) = 236 W (1) S = 2,8 m2 La = 6m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 2 is accepted (I = 15,0 cm).
■
Corridor, room No. 7, 1st floor The heat given off by the pipes leading to the other panels is considered sufficient here.
The solutions prepared are accepted twice to confirm the calculation of the materials for both the dwellings on the first floor. A drawing follows, plus the print-outs which show the results obtained (see key to symbols used at the end of the panel dimensioning). (1)
For calculation of Q, see: Notes and conventions used.
114
115
116
117
118
119
120
Dimensioning of branches and manifolds on mezzanine For the GENERAL DATA function, enter:
H pann = 2.000 mm w.g. Rs = 1,633 m2K/W ts = + 5°C
(previous val. 1.900) (previous val. 1,061) (previous val. +20)
The dimensioning of the third manifold is then required, and, accepting the relevant data offered as default, the dimensioning of the branches is commenced.
■
Living room, room No. 1, mezzanine The high heat output required (2,900 W) means that two panels should be used (see item DIMENSIONING OF PANELS, sub-chapter PANEL FLOW). Therefore the following is proposed:
Branch 1 - Living room 1A:
Q = ( 2.420 / 2 ) - ( 163 / 2 ) = 1.129 W (1) S = 34 / 2 = 17 m2 La = = 1m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 3 is accepted (I = 22,5 cm). The same data is proposed and the same solution is also accepted for branch No. 2 - Living room 1 B
■
Kitchen, room No. 2, mezzanine The heat output required and the available area are such that a single panel will be sufficient. Therefore the following is proposed: Branch 3 - Kitchen 2:
Q = 990 - ( 133 / 2 ) = 924 W (1) S = 14 m2 La = 8m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 3 is accepted (I = 22,5 cm).
■
Bathroom, room No. 3, mezzanine Same as for 2nd floor bathroom, dimensioning a panel with Q = 360 W e I = 7,5 cm. For dimensioning of the heat emitter, the following is proposed Branch 5 - Bathroom 3B:
Q = 520 - 360 - ( 51 / 2 ) = 135 W (1) La = 12 m other data as proposed by the programme as default
The solution proposed by the programme is accepted, which provides for a heat emitter consisting of 5 elements, model 680/4 (defined as default).
(1)
For the calculation of Q, see: Notes and conventions used.
121
■
Bedroom, room No. 4, mezzanine The heat output required and the available area mean that a single panel is sufficient. The following is therefore proposed: Branch 6 - Bedroom 4
Q = 1.150 - ( 154 / 2 ) = 1.073 W (1) S = 20 m2 La = 6m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 4 is accepted (I = 30,0 cm).
■
Bedroom, room No. 5, mezzanine Same as for 1st floor bathroom, a reduced area of 14 m2 is considered. The following is therefore proposed: Branch 7 - Bedroom 5:
Q = 770 - ( 103 / 2 ) = 719 W (1) S = 14 m2 La = 8m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 4 is accepted (I = 30,0 cm).
■
Bathroom, room No. 6, mezzanine The heat output required and the available area mean that a single panel is sufficient. The following is therefore proposed: Branch 8 - Bathroom 6
Q = 250 - ( 34 / 2 ) = 233 W (1) S = 2,8 m2 La = 6m other data as proposed by the programme as default
Of the solutions relating to the data proposed, No. 2 is accepted (I = 15,0 cm).
■
Corridor, room No. 7, mezzanine The heat given off by the pipes leading to the other panels is considered sufficient here.
The solutions prepared are accepted twice to confirm the calculation of the materials for both the dwellings on the mezzanine floor. A drawing follows, plus the print-outs which show the results obtained (see key to symbols used at the end of the panel dimensioning).
(1)
For the calculation of Q, see: Notes and conventions used.
122
123
124
125
126
127
128
129
130 Dimensioning of distribution network The distribution network is dimensioned using the method of constant linear head losses, taking as a guide value r = 10 mm w.g./m and using Table 4 in the 1st Handbook, item STEEL PIPES. The following is thus obtained: – 2nd floor riser - manifold connection pipes – 1st floor riser - manifold connection pipes – mezzanine riser - manifold connection pipes – 1st floor - 2nd floor riser section – 1st floor - mezzanine riser section – mezzanine - heating centre riser section
G =1.478 l/h G =1.081 l/h G =1.108 l/h
ø = 1 1/4” ø= 1” ø= 1”
G= 1.478 · 2 = 2.956 l/h G = 2.956 + 1.081 · 2 = 5.118 l/h G = 5.118 + 1.108 · 2 = 7.334 l/h
ø = 1 1/2” ø= 2” ø = 2 1/2”
The head obtained at the base of the circuit is determined (see practical methods, 1st Handbook) by adding together: •
the head required upstream from the last manifold (Hzone);
•
the continuous loss of head from the circuit (Hcont) considered conventionally as equal to the product of: - r = guide value of linear constant head loss, - l = circuit length;
•
the localised head losses (Hloc) taken as equal to 60% of the continuous head loss.
The result is thus: - Hzone (2nd floor) = 1.893 mm w.g.(see 2nd floor manifold print-out) - Hcont = l · r = (la + lc + lo ) · r = 40 · 10 = 400 mm w.g. where:
la = 12 m length 2nd floor manifold-riser connecting pipe lc = 12 m length riser pipes and assuming: lo = 16 m length heating centre - riser connecting pipes - Hloc = 400 · 0,6 = 240 mm w.g. The head obtained at the base of the circuit is thus: H = 1.893 + 400 + 240 = 2.533 mm w.g.
Calculation of total heat output The total heat output emitted by the panels (upwards and downwards) and the heat emitters is calculated by adding together the heat outputs given off by the emitters of each manifold (see relevant print-outs). The result is thus: - Q tot = 8.141 · 2 + 6.576 · 2 + 7.040 · 2 = 43.514 W
131
PANEL SYSTEMS DATA SURVEY CALEFFI HANDBOOKS SOFTWARE
Project File:
Date:
Client:
Installer:
System location:
Manifold:
Piping:
Centre-to-: centre distances
Notes:
panels:
D e = — mm
D i = — mm
Heat emitters:
D e = — mm
D i = — mm
❍
I 1 = 7,5
I 2 = 15,0
I 3 = 22,5
I 4 = 30,0
I 5 = 37,5
❍
I 1 = 5,0
I 2 = 10,0
I 3 = 15,0
I 4 = 20,0
I 5 = 30,0
❍
I1 = —
I2 = —
I3 = —
I4 = —
I5 = —
I N D I V I D U A L
M A N I F O L D
D A T A
S U R V E Y
CALEFFI HANDBOOKS SOFTWARE
Project File:
H pann:
Manifold n:
t max:
mm w.g.
cvz:
°C
PANEL DATA SURVEY N
Room
Qdisp
Q (±)
Q
Sloc
Span
Szp
La
ta
ts
Rp
sm
Rs
vi
ta
dt
cv
cd
vi
HEAT EMITTERS BRANCH DATA SURVEY N
Room
Q
La
Heat Emitter
( code ) (
)
(
)
(
)
(
)
134
NOTES
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135
NOTES
_________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________
136
BIBLIOGRAPHY
1
J. RIETSCHEL - W. RAISS Traité de chauffage et de ventilation Librairie Polytechnique Ch. Béranger - Paris et Liège
2
M. DONINELLI - P. RAFFAGLIO Pannelli radianti a pavimento Scantec - Bernareggio (Mi)
3
PIERRE FRIDMANN Le calcul des planchers chauffant a eau chaude Les editions parisiennes
4
A. MISSENARD Le chauffage et le refraichement par rayonnement Editions Eyrolles (Paris)
5
F. KREYTH Principi di trasmissione del calore Liguori Editore
6
J. J. BARTON Electric floor warming Georges Newnes (London)
7
AUTORI VARI Il riscaldamento a pannelli radianti con serpentine in acciaio Bollettino n. 26 Dalmine
137
THE CALEFFI HANDBOOKS
1
DISTRIBUTION NETWORKS Mario Doninelli
2
DESIGN PRINCIPLES OF HYDRONIC HEATING SYSTEMS Mario Doninelli
3
SYSTEMS WITH MANIFOLDS Mario Doninelli
4
SYSTEMS WITH RADIANT PANELS Mario Doninelli
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