manual caleffi

8/13/2019 Manual Caleffi

1/156

MARIO DONINELLI

SYSTEMS

WITH RADIANT PANELS


2/156

MARIO DONINELLI

SYSTEMS

WITH RADIANT PANELS

andbooksCaleffi


3/156


4/156

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

techno logically 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 sp irit in which we

have tried to provide our cont ribution.

As amply illustrated in this Handbook, there is no longer any reason to doubt thevalidity 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 th is is most important, in a sector likeours, 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 cont inuously chang ing world. Only in this way can we offertechno logically advanced solutions, which are competitive and thus able to meet

our c lientsreasonable demands.

Finally, I should like to express my warmest thanks to the Author of this publicationand 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.


5/156


6/156

This Handbook offers an analysis of the main aspects of the performance,

product ion 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 therelevant op tions 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) aredimensioned 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 construct ion 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 informat ion 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

PREFACE


7/156

N O T E S

GENERAL STRUCTURE

Definitions, graphs, tables, formulae, command functions, examples and advice aregiven 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 isclearly shown in rounded brackets.

Graphs, tables and formulae have consecutive numbering linked only to the contextof the item in which they are contained. Longer items, sometimes introduced by ashort contents list, are broken down into chapters and sub-chapters.

DRAWINGS AND DIAGRAMS

The items are supplemented by drawings and diagrams which illustrate the essentialfunctional aspects of the systems, equipment and details described. No installationdrawings are enclosed.

SIGNS, SYMBOLS AND ABBREVIATIONS

Signs and symbols (relating to mathematics, physics, chemistry, etc.) are those incurrent use. As far as possible, the use of abbreviations has been avoided; those whichare used are specified in each case.

UNITS OF MEASUREMENT

The International System has not been rigidly applied. Traditional technical units ofmeasurement 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 ofthe technicians and fitters.


8/156

GREEK ALPHABET

Physical sizes, numeric coefficients and constants are often represented by letters ofthe Greek alphabet. These letters are shown below with their pronunciation.

Letters of the Greek Alphabet

Upper Case Lower Case Name Upper Case Lower Case Name

alpha nu

beta xi

gamma omicron

delta pi

epsilon rho

zeta sigma

eta tau

theta upsilon

iota phi

kappa chi

lambda psi

mu omega


9/156

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________

N O T E S


10/156

HISTORIC BACKGROUND..................................................................................................................... 4

ADVANTAGES OF PANEL SYSTEMS .................................................................................................... 6- THERMAL WELL-BEING .................................................................................................................................. 6- AIR QUALITY .................................................................................................................................................... 8- HEALTH CONDITIONS .................................................................................................................................... 8- ENVIRONMENTAL IMPACT ........................................................................................................................... 8- HEAT USABLE AT LOW TEMPERATURE ...................................................................................................... 9- ENERGY SAVING ............................................................................................................................................. 9

LIMITATIONS AND DISADVANTAGES OF PANEL SYSTEMS ............................................................. 10- LIMITATIONS CONNECTED WITH THE SURFACE TEMPERATURE OF THE FLOOR ............................ 10- THERMAL INERTIA AND METHOD OF USE OF SYSTEMS ......................................................................... 10- DISADVANTAGES CONNECTED WITH DESIGN ASPECTS ........................................................................ 11

COOLING OF ROOMS ............................................................................................................................. 11

COST OF PRODUCTION AND MANAGEMENT .................................................................................... 12

APPLICATIONS ..................................................................................................................................... 12

PANEL CONTAINMENT STRUCTURES ........................................................................................................... 14- INSULATING MATERIALS ............................................................................................................................... 15- PERIPHERAL JOINTS ....................................................................................................................................... 16- MAIN JOINTS .................................................................................................................................................... 16- EDGE JOINTS .................................................................................................................................................... 17

- SLAB .................................................................................................................................................................... 17

- FLOORS .............................................................................................................................................................. 17DISTRIBUTION OF HEAT-CARRYING FLUID.............................................................................................. 18- MANIFOLDS ....................................................................................................................................................... 18

- PANELS ............................................................................................................................................................... 19

PRESSURE TEST AND START-UP ..................................................................................................................... 23

Part one

GENERAL NOTES AND METHODS OF CALCULATION

GENERAL NOTES Page 3

CONSTRUCTION OF RADIANT PANEL SYSTEMS Page 13

C O N T E N T S


11/156

CALCULATION PARAMETERS.............................................................................................................. 34

UPWARD HEAT FLOW FROM A PANEL .............................................................................................. 36- LOGARITHMIC MEAN BETWEEN FLUID TEMPERATURE AND AMBIENT TEMPERATURE ............... 37- FACTORS RELATING TO PIPE CHARACTERISTICS ..................................................................................... 38- FACTORS RELATING TO THERMAL RESISTANCE OF FLOOR ................................................................... 39- FACTORS RELATING TO CENTRE-TO-CENTRE DISTANCE OF PIPES ..................................................... 40- FACTORS RELATING TO THICKNESS OF SLAB ABOVE PIPES ................................................................. 41- FACTORS RELATING TO OUTER DIAMETER OF PIPE ............................................................................... 42

TOTAL HEAT EMISSION FROM A PANEL ............................................................................................ 43

CALCULATION OF PANELS ............................................................................................................................... 45

PARAMETERS REQUIRED.................................................................................................................................. 50- CENTRE-TO-CENTRE DISTANCES ................................................................................................................. 50- PRESET HEAD ................................................................................................................................................... 51- MAX. DESIGN TEMPERATURE ...................................................................................................................... 51- HEAT OUTPUT REQUIRED ............................................................................................................................. 52- AMBIENT TEMPERATURE .............................................................................................................................. 52- TEMPERATURE OF ROOM OR GROUND BELOW ...................................................................................... 53- THERMAL RESISTANCE OF FLOOR ............................................................................................................... 54

- THERMAL RESISTANCE UNDER PANEL ...................................................................................................... 58

PARAMETERS TO BE DETERMINED ................................................................................................................ 62- SURFACE TEMPERATURE OF FLOOR ............................................................................................................ 62- TEMPERATURE DIFFERENCE OF HEATING FLUID .................................................................................... 64- FLOW IN PANEL ............................................................................................................................................... 64- HEAD REQUIRED ............................................................................................................................................. 65- LENGTH OF PANEL .......................................................................................................................................... 65- FLUID VELOCITY .............................................................................................................................................. 66- TOTAL HEAT OUTPUT EMITTED BY PANEL ............................................................................................... 66- HEAT OUTPUT EMITTED DOWNWARDS .................................................................................................... 66- MEAN HEAT OUTPUT EMITTED UPWARDS BY ONE METRE OF PIPE ................................................... 66- MEAN HEAT OUTPUT EMITTED DOWNWARDS BY ONE METRE OF PIPE ........................................... 66

CONTROL SYSTEMS Page 24

HEAT FLOW EMITTED BY A PANEL Page 33

DIMENSIONING OF PANELS Page 44


12/156

ZONE VALVE ARCHIVE ...................................................................................................................................... 70ARCHIVE OF VALVES FOR HEAT EMITTERS ................................................................................................ 72HEAT EMITTERS ARCHIVE............................................................................................................................... 74

MAIN PARAMETERS ARCHIVE ......................................................................................................................... 78MANIFOLD DATA ARCHIVE ............................................................................................................................. 80DATA ARCHIVE FOR PIPES AND CENTRE DISTANCES ............................................................................. 81

MANIFOLD MANAGEMENT AND PROCESS PRINTING ...................................................................... 84

BRANCH CIRCUITS MANAGEMENT....................................................................................................

85PANEL DIMENSIONING ........................................................................................................................ 86- ACQUISITION OF PROJECT DATA ................................................................................................................ 86- DEVELOPMENT OF CALCULATIONS ............................................................................................................. 88- PRESENTATION OF THE DATA PROCESSED ............................................................................................... 89

CALCULATION OF HEAT EMITTERS.................................................................................................... 90- ACQUISITION OF PROJECT DATA ................................................................................................................ 90- DEVELOPMENT OF CALCULATIONS ............................................................................................................. 91- PRESENTATION OF THE DATA PROCESSED ............................................................................................... 91

SELECTION OF SOLUTIONS PROCESSED ............................................................................................. 92

PRINTER CONFIGURATION Page 68

MATERIALS ARCHIVES Page 69

GENERAL DATA ARCHIVES Page 77

PROJECT ARCHIVE MANAGEMENT Page 82

CALCULATION PROGRAMME Page 83

Part two

PROGRAMME FOR THE DIMENSIONING

OF SYSTEMS WITH PANELS


13/156

EXAMPLE OF CALCULATION USING CALEFFI SOFTWARE ............................................................... 94- ANALYSIS AND SELECTION OF MAIN PARAMETERS ................................................................................ 96- SELECTION OF MANIFOLDS AND VALVES................................................................................................... 100- SELECTION OF PIPE AND CENTRE-TO-CENTRE DISTANCES................................................................... 100- NOTES AND CONVENTIONS USED ............................................................................................................... 101- ACTIVATION OF PROJECT FILE ..................................................................................................................... 102- DIMENSIONING BRANCHES.......................................................................................................................... 103- PRINT-OUT AND SYMBOLS............................................................................................................................ 128

- DIMENSIONING THE DISTRIBUTION NETWORK ..................................................................................... 130- CALCULATION OF TOTAL HEAT OUTPUT .................................................................................................. 130

BIBLIOGRAPHY Page 136

Part three

EXAMPLE OF CALCULATION


14/156

GENERAL NOTESAND

METHODS OF CALCULATION


15/156

RUGOSIT

Summary

GENERAL NOTES

RUGOSITCONSTRUCTION

OF RADIANT PANEL SYSTEMS

RUGOSITCONTROL SYSTEMS

RUGOSITFLOW OF HEATFROM A PANEL

RUGOSITPANEL DIMENSIONING


16/156

3

HISTORIC BACKGROUND

COOLING OF ROOMS

COST OF CONSTRUCTIONAND MANAGEMENT

APPLICATIONS

ADVANTAGESOF PANEL SYSTEMS

HEALTH CONDITIONS

ENVIRONMENTAL IMPACT

HEAT AVAILABLEAT LOW TEMPERATURE

ENERGY SAVING

LIMITATIONS AND DISADVANTAGESOF PANEL SYSTEMS

AIR QUALITY

THERMAL COMFORT

LIMITATIONS CONNECTEDWITH SURFACE TEMPERATURE OF FLOOR

THERMAL INERTIAAND METHOD OF USE OF SYSTEM

DISADVANTAGES LINKEDWITH DESIGN ASPECTS

G EN ER A L N O T E S


17/156

4

HISTORICAL BACKGROUND

It may be of use to analyse the history of panel heating to give a better overallview of its development in the context of systems in general, and, in particu-lar, this may serve to illustrate why these systems are sometimes seen with a

certain diffidence, and used only for applications which are entirely secondaryand partial.

THE FIRST FLOOR-HEATING SYSTEMS

The idea of using the floor as a heat emission surface goes back over two thousandyears. Heating systems inspired by this idea were built by the Chinese, Egyptiansand 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 therooms to be heated; it was, in practice, single room heating.The Romans, however, used far more complex, advanced systems. Using the smokefrom a single external hearth, they were able to heat several rooms and even severalbuildings, thus achieving the first central-heating type system.

However, it was not until the start of this century that underfloor heating appearedin its present form. And it was an Englishman, Professor Baker, who was first topatent this type of system using the titlesystems for heating rooms wi th hot water car-ried by underfloor piping. In London in 1909, Crittal Co. acquired the patent rightsand heated one of the Royal palaces with this new system.

However, it was not until the period of the great reconstruction after the secondworld 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 ofpanel heating - these were the constant unavailability of heat emitters and the easeof 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 tech-nique.

Very soon, however, it was noted that the equipment was causing numerousphysiological problems, such as poor circulation, high blood pressure, headachesand excessive sweating. Problems of this nature were so serious and well-documentedthat certain European countries set up Commissions to identify the causes.


18/156

5

CAUSES OF PHYSIOLOGICAL PROBLEMS

The results of the various Commissions of enquiry agreed that, in the systemsconstructed, the physiological problems were due to two values being toohigh: (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, thefloor temperature should not exceed 2829C. In fact, in the systems examined,far higher temperatures were found, even in excess of 40C.It was also demonstrated that the excessive heat accumulated in the floor slabs of thesystems meant overheating of the rooms above physiologically acceptable levels.

The Commissions themselves, however, did not publish any negative judge-ments of panel systems.They demonstrated that these systems, if constructed for alow surface temperature and with a not excessively high thermal inertia, can offerheat comfort greatly superior than that which can be obtained with radiator or con-vector equipment.

Whilst not being a condemnation, the Commissions results in fact constituteda strong dis-incentive to produce panel systems, and it was some years beforethey made any significant comeback.

THE NEW SYSTEMS

The event which again drew attention to these systems was the energy crisisin the 1970s.Under the impetus of this crisis, almost all European countries issued laws which re-quired efficient heat insulation of buildings, and it was thus possible to heat roomswith 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 heatthe rooms with floor temperatures lower than the physiological maximum, and thisin turn made it possible to reduce the thermal inertia of the system.A further reduction in thermal inertia was obtained by producing floating floorswith 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 systemswith a high heat output.

Nowadays in Europe, the new panel systems are installed mainly in theNorthern countries, where they are experiencing a deserved success, largelydue to the advantages(analysed below)which they can offer.


19/156

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 heatconditions in a room, slightly warmer areas must be maintained at floor leveland slightly cooler ones at the ceiling level.The system most suited to providing these conditions consists of radiatingfloors, 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 for-mation of convection currents of hot air at ceiling level and cold air at floor level.


20/156


21/156


22/156

9

HEAT USABLE AT LOW TEMPERATURE

Due to their high dispersion area, panel systems can use the heat-carrying fluid atlow temperatures.This characteristic makes their use convenient with heat sources whose effi-

ciency (thermodynamic or economic) increases when the temperature requiredis 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 re-turn temperature of the primary fluid.

ENERGY SAVING

In comparison with the traditional heating systems, panel systems produceconsiderable energy savings, for two basic reasons:

1. the higher operating temperature,which permits (for the same ambient tem-perature) average savings varying from5 to10%;

2. the lower temperature gradient between floor and ceiling, which provideshigher 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 en-ergy savings of between10and15%.


23/156

10

LIMITATIONS AND DISADVANTAGES OF PANEL SYSTEMS

These relate mainly to aspects connected (1) with the surface temperature of thefloor, (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 tempera-ture of the floor must be below the values given under the headingDIMEN-SIONING OF PANELS, sub-chapterSURFACE TEMPERATURE OF THE FLOOR.As specified in the said sub-chapter, these values make it possible to determine themaximum heat output (Qmax) which can be transferred by a panel.

IfQmax is less than the required output (Q), there are two possible situations:

1. Qmax is less thanQonly in a few rooms,in which case additional heat emitters can be used. For example, Qmax can comefrom the panels and the remaining output from radiators.

2. Qmax is less thanQ 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 orderto transfer heat, they use the structures in which the panels themselves areburied.

In environments heated with a certain degree of continuity (and good insula-tion under the panels), the thermal inertia of the system poses no problems andpermits:

good adaptability of the system to the external climatic conditions;

interruptions or slowing down of functions, with system on and off timeswhich 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 consider-able phase variations between the starting times and the times of actual use.Thus in these cases, other heating systems should be used.


24/156

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 fromthe parameters required to determine the heat losses from the rooms, the design ofpanel systemsalso requires detailed knowledge of all the constructional in-formation regarding the floors and floor slabs.

more complex, laborious calculations, although due to the greater commit-ment, 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 consid-ered 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 con-densation phenomena. For this reason, it is difficult to obtain a cooling outputgreater than 40-50 W/m2.

The inability to dehumidify depends in fact on the nature of the panel systemitself, whose surfaces(i.e. the floor) cannot cause condensation and evacuationof part of the water contained in the air. Healthy hygrometric conditions can,therefore, only be obtained with the use of dehumidifiers, in conjunction with panelsystems, with a cost and space requirement which is not always acceptable.


25/156

12

CONSTRUCTION AND DESIGN COSTS

It is practically impossible to establish significant mean data with regard tothe 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 average10% to30%more than radiator systems with climatic control.

With regard, however, to running costs, panel systems allow savings averag-

ing10to15% in comparison with traditional systems(see sub-chapter ENERGYSAVING). They thus allow the additional construction cost to be offset relativelyquickly.

APPLICATIONS

On their own, or integrated with air-conditioning systems, panel systems canbe used to heat: detached and terraced houses, homes in high-rise blocks, nursinghomes, schools, gyms, swimming pools, museums, libraries, hospitals, hotels, shopsand workshops.

They can also be used to clear ice and snow- car parks, garage ramps, steps, run-ways and sports fields.


26/156

13

PRESSURE TEST AND START-UP

PANEL CONTAINMENTSTRUCTURES

MAIN JOINTS

EDGE JOINTS

SLABS

FLOORS

DISTRIBUTIONOF HEAT-CARRYING FLUID

PERIPHERAL JOINTS

INSULATING MATERIALS

MANIFOLDS

PANELS

C O N S T R U C T I O N

O F R A D I A N T P A N E L SY ST E M S


27/156

14

PANEL CONTAINMENT STRUCTURES

These consist mainly of the floor(or solid foundation on the ground), the insulat-ing material, the slab and the floor tiles or finish.


28/156

15

INSULATING MATERIALS

The insulation under the panels is used (1) to reduce the heat given off down-wards 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 recom-mended, because they have high thermal inertia values.

Insulation systems can have flat surfaces or pre-formed surfaces for direct an-chorage of the pipes.

Flat surface insulation materialsare normally used in buildings to insulate tradi-tional floors.As they have no supports for anchoring pipes, they require the use of electro-weldedframeworks or suitable metal profiles with junction clips and fixing supports.The most frequently used flat surface insulating materials are expanded and extrudedpolystyrene. The latter, in particular, due to form and high density, make itpossible 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-resistantand thus cannot be used tomake floors subject to compression stresses, such as for example industrial flooring.

If several materials are to be used for making the insulating layer, the leastcompression-resistant materials must be positioned in the upper layers. In ad-dition, the insulating panels must be fitted in close contact with each other and (inthe case of multiple layers) have offset joints.

In order to prevent deterioration of the insulating materials in use, two typesof 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 polyethylenesheets (min. thickness0,15mm) or other equivalent protection;

2.Protection against rising damp.This is only required for floors in direct contact with the ground or in verydamp rooms. It can be made under the insulation with polyvinyl chloride sheets(min. thickness0,4mm) or other equivalent protection


29/156

16

PERIPHERAL JOINTS

These are used to provide (1) expansion of the floor slab, (2) heat insulationbetween the slab and the walls, (3) a sound gap between floor and walls.

This is done using insulating strips (normally expanded polyethylene 68 mmthick) positioned along the walls and bounding the various construction ele-ments of the floor and slab (see diagram in the chapter PANEL CONTAINMENTSTRUCTURES).

The strips must be positioned carefully and overlapped by at least 10cm at the junc-tion points. Their upper parts must protrude beyond the block and be trimmed onlywhen the floor is finished.

MAIN JOINTS

These permit expansion of the slab at the locations of the structural joints ofthe building and in the case of large floor areas.

Without joints of this type, constructing floors of area exceeding40 m2 or of lengthgreater than 8 m is not advisable. In L-shaped rooms, the maximum area can be ex-tended to80m2.


30/156

17

EDGE JOINTS

These are used to guide the positioning of the slab in relation to doors andother openings.They are made using a trowel (up to a depth of 34 cm) when the slab begins to dry.

SLAB

This must be made with a fluid mixture to prevent the formation of small airpockets which can obstruct normal heat transfer. Appropriate chemicals can beadded to improve the fluidity of the casting.

The components and proportions of the mix depend on the class of strengthto be obtained.

The minimum thickness of the slab over the pipes must be:

20mm for flush slabs, i.e. for slabs on which a sub-base is to be made later,onto which the tiles will be fitted.

40mm for finish slabs, i.e. for slabs on which the floor is to be laid or stuckdirectly afterwards.

TILES (FLOOR FINISH)

Panel systems do not require special types of flooring or special techniques for fit-ting.However, it is advisable not to use floor finishes with a thermal resistancegreater than0,150m2K/W (see item PANEL DIMENSIONING, sub-chapter FLOOR

THERMAL RESISTANCE).


31/156

18

DISTRIBUTION OF THE HEAT-CARRYING FLUID

This consists of taking the fluid through the main distribution system, the manifoldsand 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 exa-

mi-ned below.

MANIFOLDS

These are normally made of brass with independent flow and return connec-tions.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.


32/156

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 differentfrom 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 polypropy-lene (PP) pipes are used.All the plastic pipes must havebarriers to prevent the diffusion of oxygen.Theoxygen contained in the air must be prevented from diffusing into the pipes, as thisgas can cause corrosion of the boiler and any metal pipework.

The diameters usually used for making the panels are16/13 and 20/16. 12/10 and25/20are used only for special applications.

Formation of the panels

Each room must be heated with one or more specific panels.This makes it pos-sible to control room temperatures independently, in other words without alteringthe heat balance of other rooms.

The panels can be made spiral or coiled.These are systems which, with the samedistance between centres and surface, deliver the same amount of heat, but the spiralsystem is generally preferable as:

it provides a more even surface temperatureas (unlike the case of the coil), itsflow and return pipes lay alternately;

it is easier to implement, as the shape of the spirals only requires two bends at180 to the central ones, in other words those in which the formation of the spiralis inverted.

The coil formation is suited above all to rooms of irregular shape or specialapplications,such as, for example, de-icing ramps.


33/156

20

The panels can have constant or variable centre-to-centre distanceswith pipescloser together where there are areas of glass or highly dispersive walls.


34/156

21

With coil panels, the flow must be towards the outer walls in order not to in-crease the already sensitive differences in surface temperature at the floor, whichcharacterise this distribution system.

The distances between pipes and the structures bounding the environment

must be at least: 5cm in the case of walls and pillars, 20cm in the case of flue ducts, fireplaces and lift shafts.

The pipes of the panels must not interfere with discharge pipesand must notpass under sinks, shower trays, WCs or bidets, unless these are of the suspended type.


35/156

22

Installation

The pipes must be transported, stored and fitted in such a way as to avoid sitedamage 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 buildingare only crossed by the pipes of the maindistribution system;

2. the other main jointsare crossed only by pipes protected with a sheath of com-pressible material of min. length 30 cm on either side of the joint, diameter double the external diameter of the pipe.


36/156

23

PRESSURE TEST AND START-UP

Before covering with concrete, the panels must be tested at a pressure at leastequal to the working pressure, with a minimum of 6 atm.This pressure mustbe maintained and constantly checked throughout the spreading of the concrete.

If there is a risk of frost, antifreeze additives compatible with the panel pipesshould be used.

The system must not be activated until the slab and the floor are completelydry. In general, this takes at least 21 days from casting. The use of synthetic addi-tives makes it possible to reduce this period considerably, but it will still be not lessthan7days.

The heating must be started maintaining a flow temperature of 25C for atleast3days. Subsequently, the flow temperature can be gradually raised to the de-

sign value.


37/156

24

Climatic controlwith pre-assembled unit

Climatic control

with 3-way valve

Climatic controlwith 2-way valve

upstream from a heat exchanger

Fixed point regulationwith 3-way valve

and anti-condensation pump

Climatic controlwith 3-way valve

and anti-condensation pump

Climatic controlwith 3-way valve,

anti-condensation pump and by-pass

C ON T R O L SY ST E M S


38/156

25

Panel system control equipment must be able to:

1. permit the heat transfer required to take place in such a way as to optimisethe 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 problemswhich could endanger the boiler itself.

In order to optimise the heat emission, climatic type controls should usuallybe adopted. In fact these controls make it possible to minimise the heat accumulat-ed in the floor slabs and thus in turn to minimise the time required for the system torespond to variation of the required heat output. Either simple climatic controls orintegrated climatic controls with thermoelectric valves interlocked with room ther-mostats can be conveniently adopted.

Fixed point controls are suggested only for systems which are not workingcontinuously,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 isexceeded, 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 temperaturemust be maintained at over55C.For this purpose, anti-condensation pumps and motorised valves with override de-vices can be used.

Operating diagrams of the systems most used for controlling panel systemsfollow.


39/156

26

Climatic control with pre-assembled unit

This solution is valid for small to medium-sized systems.Generally, the pre-as-sembled units available do not permit flows greater than 5.0006.000 l/h.


40/156

27

Climatic control with 3-way valve

This control can be adopted in systems where there are not problems withflue gas condensation;for example in systems with heat pumps or heat exchangers.


41/156

28

Climatic control with 2-way valves upstream from a heat exchanger

This type of control can be used in district heating substations.


42/156

29

Fixed point regulation with 3-way valve and anti-condensation pump

This solution is suited to systems operating intermittently, as it minimises thetime required to reach the steady condition. It does not, however, allow a goodresponse to output variations in continuous operation.


43/156

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 sys-tems 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.


44/156

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 openingrange,thus preventing any chatter and wear on the valve.

Disadvantages: Requires skilled personnel for commissioning and calibration.


45/156

32

The diagram on the previous page shows the regulating and by-pass valves di-mensioned on the basis of the following flows:

QtotGv =

1,16 . (tm tr)

Gb = Gp Gv

where:

Gv = flow through 3-way valve, l/hQtot = total heat output of panel circuit, W

tm = primary circuit flow temperature (boiler circuit),Ctr = secondary circuit return temperature (panels circuit),C

Gb = by-pass flow, l/hGp = panels circuit flow, l/h

(1)

(2)


46/156

33

CALCULATION PARAMETERS

UPWARD FLOW OF HEATFROM A PANEL

FACTOR RELATINGTO FLOOR THERMAL RESISTANCE

FACTOR RELATING TO PIPECENTRE-TO-CENTRE DISTANCE

FACTOR RELATING TO THICKNESSOF SLAB ABOVE PIPES

FACTOR RELATINGTO OUTER DIAMETER OF PIPE

TOTAL FLOW OF HEATFROM A PANEL

FACTOR RELATINGTO PIPE CHARACTERISTICS

LOGARITHMIC MEANBETWEEN FLUID TEMPERATURE

AND ROOM TEMPERATURE

F L OW O F H E AT

F R O M A PA N E L

In order to be able to use the programme, you do not need to read the chap-ters and sub-chapters marked with an asterisk (see preface).

*

*

*

*

*

*

*

*


47/156

34

CALCULATION PARAMETERS

The parameters which are used to determine the heat output delivered by a panel canbe broken down into the following groups:

1. parameters relating to the surrounding conditions:

- ta room temperature, C

- ts temperature of room or ground below, C

2. parameters relating to the panel configurations:

-S covered surface of panel, m2

- I pipe fitting centre-to-centre distance, m

3. parameters relating to the type of pipe:

-De pipe external diameter, m

-Di pipe internal diameter, m

- t pipe thermal conductivity, W/mK

4. parameters relating to the panel containing structure:

-Rp thermal resistance of floor, m2K/W

-sm thickness of slab above pipes, m- m thermal conductivity of the slab,W/mK

-Rs thermal resistance under panel, m2K/W

5. parameters regarding the temperature of the heat-carrying fluid:

- te flow temperature of heat-carrying fluid, C


48/156

35


49/156

36

UPWARD FLOW OF HEAT FROM A PANEL (1)

This is calculated using the following formula:

Q = S . t . B . Fp . FI . Fm . FD

where: Q = upward flow of heat given off by panel, WS = covered surface of panel, m2

t = logarithmic mean between the temperature of the fluid and the ambienttemperature,C

B = factor relating to pipe characteristics,W/m2K

Fp = factor relating to thermal resistance of floor, dimensionlessFI = factor relating to centre-to-centre distance of pipes, dimensionlessFm= factor relating to thickness of slab above pipes, dimensionlessFD = factor relating to outer diameter of pipe, dimensionless

(1)There is no need to read this chapter (see Preface).

(1)


50/156

37

LOGARITHMIC MEAN BETWEEN THE TEMPERATURE OF THE FLUID ANDTHE AMBIENT TEMPERATURE (1)


(te tu)t =

(te ta)ln (tu ta)

where: t = logarithmic mean of fluid temperature and ambient temperature,C

te = flow temperature of heating fluid, Ctu = return temperature of heating fluid, C

ta = temperature of ambient air, C

ln = natural logarithm

(1)There is no need to read this sub-chapter (see Preface).

(2)


51/156

38

FACTOR RELATING TO THE PIPE CHARACTERISTICS (1)

This is indicated by the symbol Band it is considered that:

B = B0 = 6,7W/m2K for pipes with: - st0 = 0,002 thickness, m

- t0 = 0,350 thermal conductivity, W/mK

For pipes of different thickness and thermal conductivity, the factor (B) is calculatedusing the formula(3)shown below:

1 1 1,1 1 De 1 De = + .Fp.FI .Fm.FD . I .( ln ln )B B0 2t De 2st 2t0 De2st0

where: B0, st0, t0 = symbols and values defined above

Fp = factor relating to the thermal resistance of the floor, dimensionlessFI = factor relating to the centre to centre distance of the pipes, dimensionlessFm= factor relating to the thickness of the slab above the pipes, dimensionlessFD = factor relating to the outer diameter of the pipe, dimensionless

I = pipe centre-to-centre distance, mDe = outer diameter of pipe, mt = thermal conductivity of pipe, W/mK

st = thickness of pipe, m

ln = natural logarithm



52/156

39

FACTOR RELATING TO THE THERMAL RESISTANCE OF THE FLOOR (1)

This is shown with the symbol Fp. Its value can be determined from Table1,or using formula (4).

TABLE 1 - Value of factorFp

Conductivity Thermal resistance of floor, m2K/Wof slab

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

1 sm0 + m0

Fp =1 sm0

+ + Rp m

given: = 10,8 W/m2K

sm0 = 0,045 mm0 = 1,0 W/mK

and where:m = thermal conductivity of slab,W/mKRp = thermal resistance of floor, m2K/W


(4)


53/156

40

FACTOR RELATING TO PIPE CENTRE-TO-CENTRE DISTANCE (1)

Shown by the symbolFI and calculated using the formula:

FI = AI x

where the factor AI can be determined from Table2and the exponent x (forpipe centre-to-centre distances varying between0,050and0,375m)can be calculat-ed using the equation:

Ix = 1

0,075

where: I = pipe centre-to-centre distance, m

TABLE 2 - Value of factorAI

Rp = 0,00 Rp = 0,05 Rp = 0,10 Rp = 0,15

AI = 1,230 AI = 1,188 AI = 1,156 AI = 1,134

Table symbols:

Rp = thermal resistance of floor, m2K/WAI = dimensionless factor

N.B.:

For centre-to-centre distances greater than0,375

m, the heat flow (Q) can becalculated using the formula:

0,375Q = Q(0,375) .

I

where Q (0,375) represents the heat flow from a panel with centre-to-centre distancesequal to0,375m.


(5)

(6)

(7)


54/156

41

FACTOR RELATING TO THE THICKNESS OF THE SLAB ABOVE THE PIPES (1)

Shown by the symbolFmand calculated using the formula:

Fm = Amy

where the factorAmcan be determined from Table3and the exponent y(for thicknessof the slab above the pipes greater than0,015m)can be calculated using the equation:

y = 100 . (0,045 sm)

where: sm = thickness of the slab over the pipes, m

TABLE 3 - Value of factorAm

Centre-to- Thermal resistance of the floor, m2K/Wcentre

distance0,00 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


(8)

(9)


55/156

42

FACTOR RELATING TO THE PIPE OUTER DIAMETER (1)

Indicated by the symbol FD and calculated using the formula:

FD = AD z

where the factor AD can be determined from Table4and the exponent z (fordiameters between0,010and0,030m)can be calculated using the equation:

z = 250 . (De 0,020)

where: De = outer diameter of pipe, m

TABLE 4 - Value of factorAD

Centre-to- Thermal resistance of the floor, m2K/Wcentre

distance0,00 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


(10)

(11)


56/156

43

TOTAL FLOW OF HEAT FROMA PANEL (1)

This is determined using the equation:

Qt = (te tu) . G . 1,16

where: Qt = total heat output emitted by a panel, W

te = heating fluid flow temperature, Ctu = 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 + Rp +

Q m S . (ta ts)G = .[ 1 + + ](te tu) . 1,16 Rs Q. Rs

given: = 10,8 W/m2K

and where:G = flow through panel, l/hQ = upward flow of heat from a panel, W

te = heating fluid flow temperature, Ctu = heating fluid return temperature, C

sm = thickness of slab, mm = thermal conductivity of slab,W/mK

Rp = thermal resistance of floor, m2K/W

Rs = thermal resistance under panel, m2K/W

S = covered surface of panel, m2

ta = temperature of ambient air, Cts = temperature of room or ground belowC


(12)


57/156

44

CALCULATION OF PANELS

PARAMETERS REQUIRED

MAX. DESIGN TEMPERATURE

AMBIENT TEMPERATURE

TEMPERATURE OF ROOMOR GROUND BELOW

THERMAL RESISTANCE OF FLOOR

THERMAL RESISTANCE UNDER PANEL

HEAT OUTPUT REQUIRED

PRESET HEAD

CENTRE-TO-CENTRE DISTANCES

D I M EN SI O N I N G O F PA N EL S

PARAMETERS

TO BE DETERMINED

PANEL FLOW

PANEL LENGTH

FLUID VELOCITY

TOTAL HEAT OUTPUT FROM PANEL

HEAT OUTPUT EMITTED DOWNWARDS

REQUIRED HEAD

TEMPERATURE DIFFERENCE OF HEATING FLUID

SURFACE TEMPERATURE OF FLOOR

MEAN HEAT OUTPUT EMITTEDUPWARDS BY ONE METRE OF PIPE

MEAN HEAT OUTPUT EMITTEDDOWNWARDS BY ONE METRE OF PIPE


58/156

45

CALCULATION OF PANELS(1)

The formulae examined in the previous items make it possible to dimensionpanel systems.For this purpose, a method of theoretical calculation is presentedbelow, with pre-established head at the ends of the panel. The analysis and de-

velopment 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.



59/156

46

A - Checking the conditions for physiological well-being

In order to be able to ensure conditions of physiological well-being, the heat out-put transferred by the panel must not exceed the maximum output defined insub-chapterSURFACE TEMPERATURE OF THE FLOOR. It must therefore be:

Q < Qmax = S . qmax

where:Q = heat output required from the panel, WQmax = maximum output which can be transferred by the panel, WS = covered surface of panel, m2

qmax = specific output which can be transferred by the panel,W/m2

where:qmax = 100W/m2 in continuously occupied environments;qmax = 150W/m2 in bathrooms, showers and swimming pools;qmax = 175W/m2 in perimeter areas of rooms rarely used.

If Q is greater thanQmax, a heat output less than or equal toQmax must beemitted by the panel and the remaining output made up by an integratedheat 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 itera-tions, using the formulae (1) and (2) given under the headingHEAT FLOWFROMA PANEL.

(1)


60/156

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 istherefore 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 tothe 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 thetheoretical point of view) restrict the acceptability of the solution underconsideration.

However, the difference between the maximum flow temperatureand the return temperature is below the limits given in the sub-chap-terTEMPERATURE DIFFERENCE OF HEATING FLUID.

C - Calculation of flow

Noting the parameters defined in B, the return temperature (tu), the thermal re-sistance 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 previousitem.


61/156

48

D - Calculation of panel length

The panel length is calculated using the equation:

SL = La +

I

where:L = panel length, mLa= route length (both ways) between manifold and panel, mS = covered surface of panel, m2I = 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 contin-uous and localised losses of head,the value of which is determined as follows:

- the continuous head lossesare calculated by multiplying the length of thepanel by the unit head losses;

- the localised head losses are calculatedby adding together head losses due to:

the panel shut-off valves,

the panel pipe bends (on average these losses are considered to be between20 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 (whichcoincides 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 re-quired and that pre-established is offset by adjustment of the regulatingvalve provided for each panel.

(2)


62/156

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 lowerheat output, as a few watts less may take the required head below thatpre-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 andthe pre-established head , solutions whose velocity is too low must also beavoided(see sub-chapter FLUID VELOCITY)

In addition, in order to be able to proceed with the dimensioning of theheat generator and other panels, the following parameters must also bedetermined(see sub-chapter PARAMETERS TO BE DETERMINED):

Qt = total heat output emitted by panel,

Qs = heat output emitted downwards by panel,

ep = mean heat output emitted upwards by one metre of pipe,

es = mean heat output emitted downwards by one metre of pipe.

H - Zone Head

This is calculated by adding together the following:

Hp= pre-established head at the panel connections,

Hc = loss of head due to the manifold,

Hz = loss of head due to the possible presence of the zone valve,Hi = loss of head due to main shut-off valves.


63/156

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 perma-nently inhabited environments. They may, however, vary up to 40 cm in ap-plications of an industrial or commercial nature (e.g.workshops, warehouses orgarages).

The grid(or series)of possible centre-to-centre distances depends on the fixingsupports(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


64/156

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 headcirculation pumps;

1.500 to 2.500 mm w.g. for floor-standing boilers, heat exchangers orheat 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 55C with traditional boilers;

40 a 45C with district heating, condensing boilers, heat pumps;

32 a 38C with solar panels.

These values make it possible to obtain a good compromise between two dif-

ferent 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 floorsof limited thermal resistance (see sub-chapterTHERMAL RESISTANCE OFFLOOR).

It is advisable that the maximum design temperature should not exceed55C

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 coldzones.


65/156

52

HEAT OUTPUT REQUIRED

This is the output required from the panel to handle the thermal requirementof the room to be heated. This requirement must be calculated taking intoconsideration 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 gener-ally imposed by law or by contractual clauses.

Given equal ambient temperatures, it is considered that in a room heated with pan-els, the operating temperature (i.e. the temperature which will give a good ap-proximation to heat comfort in the room) is on average11,5C higher than thatwhich can be obtained by heating with heat emitters (see Item GENERALNOTES, sub-clauseENERGY SAVING).


66/156

53

TEMPERATURE OF THE ROOM OR GROUND BELOW

This is the temperature of the room or ground below the structure containingthe 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 temperaturetemperature of ground

under floor

- 20C + 3C

- 15C + 5C

- 10C + 8C

- 5C + 10C

0C + 11C

+ 5C + 12C


67/156

54

THERMAL RESISTANCE OF FLOOR

This is calculated using the formula:

spRp =

p

where: Rp = thermal resistance of the floor, m2K/Wsp = thickness of floor, mp = 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 ConductivityW/mK

Ceramic 1,00

Brick 0,90

Rubber 0,28Granite 3,20

Linoleum 0,18

Marble 3,40

Carpet 0,09

Parquet 0,20

PVC flooring 0,23

The following tables contain pre-calculated values of the thermal resistanceRpof flooring inceramic, brick, rubber, marble and parquet.

(3)


68/156

55

Table (3) shows the indicative values of the maximum specific heat outputwhich can be transferred by a panel, in relation to two variables; the thermal re-sistance of the floor and the maximum design temperature.These values (averagely valid for temperature differences of 8-12C and for plasticpipes 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 temperaturein relation to the specific output requestedand 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

Rp Maximum Design Temperature,Cm2K/W

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 1190,050 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


69/156

56

CERAMIC

TAB. 4 - Value ofRp forp = 1,00 W/mK

s Rp

6 0,006

8 0,008

10 0,010

12 0,012

BRICK


s Rp

10 0,011

15 0,017

20 0,022

30 0,033

RUBBER


s Rp

2 0,007

3 0,011

4 0,014

5 0,018


70/156

57

Table symbols: Rp = thermal resistance of floor, m2K/Ws = thickness of floor, mmp = thermal conductivity of floor,W/mK

MARBLE


sRp

10 0,003

15 0,004

20 0,006

30 0,009

PARQUET


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


71/156

58

THERMAL RESISTANCE UNDER PANEL

This is the thermal resistance of the structure below the top level of the pipesand the surrounding environment

This is calculated using the formula:

sd sis sin 1Rs = + + Rsl + +

m is in

given: = 5,9 W/m2K

and where:Rs = thermal resistance under panel, m2 K/W

sd = distance between upper level of pipes and insulation, mm = thermal conductivity of the slab,W/mK

sis = thickness of insulating material, m is = thermal conductivity of insulating material, W/mK

Rsl = thermal resistance of floor slab, m2K/W

sin = thickness of plaster, m in = thermal conductivity of plaster,W/mK

(4)


72/156

59

Table (9) shows the conductivity and thermal resistance of materials commonly locat-ed under the panels.

TAB. 9 - Conductivity or thermal resistance of materials located under panels

Material Conductivity Thermalresistance

W/mK m2K/W

Expanded clay 0,100

Concrete 1,300

Fibreglass 0,040

Plaster with lime and gypsum 0,700

Plaster with lime mortar 0,900

Polystyrene 0,035

Polyurethane 0,028

Brick floor slab: 20cm 0,32

24cm 0,35

28cm 0,37

Boards: 15cm 0,36

20cm 0,4025cm 0,43

Cork sheets 0,040

Expanded cork with binders 0,045

Expanded vermiculite 0,070

The following pages contain tables with precalculated values of thermal resis-

tance Rs for floor slab in brick, boards and floors on the ground.


73/156

60

FLOOR SLABSOF BRICK WITHPOLYSTYRENE INSULATION

FLOOR SLABSOF BOARDS WITHPOLYSTYRENE INSULATION

TAB. 10 - Rs as function of h e s

h s Rs

2,0 1,061

2,5 1,204

3,0 1,347

20 3,5 1,490

4,0 1,633

4,5 1,776

5,0 1,919

2,0 1,091

2,5 1,234

3,0 1,377

24 3,5 1,520

4,0 1,663

4,5 1,806

5,0 1,949

2,0 1,111

2,5 1,254

3,0 1,397

28 3,5 1,540

4,0 1,683

4,5 1,826

5,0 1,969


h s Rs

2,0 1,101

2,5 1,244

3,0 1,387

15 3,5 1,530

4,0 1,673

4,5 1,816

5,0 1,959

2,0 1,141

2,5 1,284

3,0 1,427

20 3,5 1,570

4,0 1,713

4,5 1,856

5,0 1,999

2,0 1,171

2,5 1,314

3,0 1,457

25 3,5 1,600

4,0 1,743

4,5 1,886

5,0 2,029

Symbols, tables10and11: Rs= thermal resistance under panel, m2K/Ws = thickness of insulating material, cmh = height of floor slab, cm


74/156

61

FLOOR ON THE GROUNDWITH POLYSTYRENE INSULATION


h s Rs

2,0 0,687

2,5 0,830

3,0 0,973

8 12 3,5 1,115

4,0 1,258

4,5 1,401

5,0 1,544

Symbols, table12: Rs = thermal resistance under panel, m2K/Ws = thickness of insulating material, cmh = thickness of concrete slab, cm


75/156

62

PARAMETERS TO BE DETERMINED

For the correct and complete dimensioning of a panel, it is necessary to deter-mine 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


qtp = ta + ( )

8,92

where: tp = surface temperature of floor,Cta = ambient temperature, Cq = specific heat output (upwards) of panel, W/m2

To avoid uncomfortable physiological conditions, the surface temperature ofthe floor should be less than:

29C in continuously occupied environments, 33C in bathrooms, showers and swimming pools, 35C in perimeter areas or rooms rarely used.

In order to comply with such values, precise limits of the heat output whichcan be transferred by a panel are required.

(5)1

1,1


76/156

63

In particular (at ambient temperature =20C), the maximum specific outputwhich can be transferred by a panel is:

qmax =8,92 . (29 20 ) 1,1 = 100 W/m2 in continuously inhabited environ-ments.

qmax =8,92 . (33 20 ) 1,1 = 150 W/m2 in bathrooms, showers and swim-ming pools.

qmax =8,92 . (35 20 ) 1,1 = 175 W/m2 in perimeter areas or rooms rarely used.

Multiplying the value ofqmaxby the area of the panel gives the maximum heatoutput which the panel can transfer to the environment without causing afeeling of discomfort (see item DIMENSIONING OF PANELS, sub-chapter

CALCULATION OFPANELS).


77/156

64

TEMPERATURE DIFFERENCE OF HEATING FLUID

This is given by the difference between the flow and return temperatures ofthe 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 heatoutput of the panel;

to avoid surface temperatures which differ too much from each other,espe-cially with coil panels;

Usually it is advisable to adopt temperature differences below810C.

PANEL FLOWThis is calculated using the formula (13) given in the item FLOW OF HEATFROM A PANEL.

Considering that the maximum flow of a panel is on average between:

200 220l/h, for pipes with Di = 16 mm

120 130l/h, for pipes with Di = 13 mm

it is possible to determine (although approximately) the maximum heat output(QG.max) which a panel can transfer in relation to its internal diameter. In par-ticular, considering a temperature difference of8C, this gives:

QG.max= (200220 ) .8.1,16 = 1.8562.042W for Di = 16 mm

QG.max= (120130 ) .8.1,16 = 1.1141.206W for Di = 13 mm

These values can be used as guidance parameters for establishing(as a first ap-proximation)whether a room needs one or more panels.


78/156

65

HEAD REQUIRED

This is calculated as shown in the chapter CALCULATION OF PANELS andmust not exceed the preset head.The difference between these two heads is offsetby 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 least200300mm w.g.It is thus possible (by opening the micrometric valve) to increase the flow throughthe panel and thus its heat output when the operating conditions are more demand-ing 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 itemFLOW OF HEATFROM 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(120150metres).


79/156

66

FLUID VELOCITY

It is advisable not to accept solutions where the fluid velocity is too low,essen-tially for two reasons: (1) to prevent the formation of air bubbles; (2) to preventthe flow of liquid from becoming laminar, as the panel emission formulae are on-

ly valid for turbulent flow.

Normally, velocities higher than0,1m/s are acceptable.Higher velocities mustbe provided for when panels are made with reverse gradients (see 1st Handbook, VE-LOCITY OF FLUID).

TOTAL HEAT OUTPUT EMITTED BY A PANEL

This is calculated using the formula (12) given in the itemFLOW OF HEATFROM A PANEL. It is used to determine the heat output which must be supplied bythe 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 re-quirement 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 thepanel by its length. It is used to determine the heat contribution of the exposedpipes to the rooms crossed by them.

MEANHEAT OUTPUT EMITTED DOWNWARDS FROM ONE METRE OF PIPE

This is calculated by dividing the heat output transmitted downwards by thepanel by its length. It is used to determine the heat contribution of the exposedpipes to the rooms underneath.


80/156

PRINTER CONFIGURATION

MATERIALS ARCHIVES

GENERAL DATA ARCHIVES

MANAGEMENT OF PROJECT ARCHIVES

CALCULATION PROGRAMME

PROGRAMME FOR THE DIMENSIONINGOF SYSTEMS WITH PANELS


81/156

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


82/156

69

M A T E R I A L S A R C H I V E S

ARCHIVE OF ZONE VALVES

2-way valves3-way valves

ARCHIVE OF VALVES FOR HEAT EMITTERS

normal valvesvalves with thermostatic option

thermostatic valvesthermoelectric valves

lock shield valves

HEAT EMITTERS ARCHIVE

modular radiatorsnon-modular radiators

convectorsfan coils


83/156

70

ZONE VALVE ARCHIVE

Allows you to store and up-date (ingroups of the same commercial series) themain characteristics of the zone valves.

Archive capacity:20 groups.

The zone valve archive is also used bythe programme for dimensioning sys-tems 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.

Brandname 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 withDn = 3/4, l/h- maximum value accepted: 9999 l/h.- whole numbers only shown on screen.

KV0,01( 1) Nominal flow rate of valve withDn = 1, l/h- maximum value accepted: 9999 l/h.- whole numbers only shown on screen.


84/156

71

COMMAND FUNCTIONS

The zone valves archive can be managed by means of the following command functions:

Scroll Enablesvertical scrolling on screen.

F1 New valve group Insertsa new valve group.

F2 Modify Modifies the elements of the valve group

except the valve type.

F3 Cancel Cancelsa valve group.

F5 Go to ... Displaysa specific group of valves.

F6 Print Printsthe valves in the archive.

F7 Save Savesthe up-dates of the archive.

ESC Exit without saving Exits from the archive without saving.


85/156

72

ARCHIVE OF VALVES FOR HEAT EMITTERS

Allows you to store and up-date (ingroups of the same commercial series) themain characteristics of the valves for

heat emitters.

Archive capacity:50 groups

The valves archive is also used by theprogramme for dimensioning systemswith 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.

Brandname Brand names of valves

- available space 11 characters.

Model Valve group model- available space 11 characters.




86/156

73

COMMAND FUNCTIONS

The valves for heat emitters archive can be managed by means of the following com-mand functions:

Scroll Enablesvertical scrolling

F1 New valve group Insertsa new group of valves.

F2 Modify Modifies the elements of the group of valvesexcept for the relevant types.

F3 Cancel Cancelsa group of valves.

F5 Go to ... Displaysa specific group of valves.

F6 Print Printsthe valves in the archive.

F7 Save Savesthe up-dates of the archive.

ESC Exit without saving Exits from the archive without saving.


87/156

74

HEAT EMITTERS ARCHIVE

Allows you to store and up-date themain characteristics of radiators, con-vectors and fan coils.

Archive capacity:200 heat emitters.

N.B.:This archive is also used by the programme for dimensioning systems withmanifolds and makes it possible to store three types of heat emitter- radiators;- convectors;- fan coils.Only radiators are already recognised and used b

manual caleffi

Documents