Danfoss Indoor Cable Floor Heating Systems Application guide

Indoor Cable Floor Heating Systems

Indoor Cable Floor Heating Systems

Application manual

Intelligent solutions with lasting effect

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Danfoss Indoor Cable Floor Heating Systems Application guide

Index

1. DEVI electrical heating systems 4

2. Application Briefing

5

2.1 General information

5

3. Product overview

6

3.1. Cables

6

3.2 Mats

6

3.3 Thermostats

7

4. Heating systems in floor

 

constructions

9

4.1. Comfort Floor Heating

9

4.2. Total (Direct) floor heating

13

4.3.Accumulating heating via electrical floor heating system 18

5.Electrical heating system floor

constructions

21

5.1. Cable heating in thick concrete

floor construction

21

5.2. Electrical heating system in

 

thin floor construction

25

5.3. Heating in wooden floors

30

Appendixes

48

A.1. C-C distance and

 

corresponding output W/m²

48

A.2. Fitting

49

A.3. Floor sensor installation

50

A.4. General installation guide

51

6. Cases

52

Our quality management system and compliances

ISO 9001

 

TS 16949

 

 

ISO 14001

 

PED

 

 

 

Along with full compliance with EU directives and product approvals

Let DEVI do the work

DEVI - an abbreviation of Dansk El-Varme Industri – was established in Copenhagen, Denmark, in 1942. As from January 1st 2003 DEVI has become a part of the Danfoss Group - Denmark’s largest industrial Group. Danfoss is one of the world’s leading companies within heating, cooling and air-

conditioning. The Danfoss Group has more than 23000 employees and serves customers in more than 100 countries.

DEVI is Europe’s leading brand of electrical cable heating systems and electric pipe heating systems with over 70 years of experience. The production of heating cables takes place in France and Poland while the head office is situated in Denmark.

The value of experience

We have installed literally millions of systems across the globe, in every conceivable setting. This experience means that we can offer you practical advice about precisely which components you need to get the best results at the lowest cost.

Indoor Cable Floor Heating Systems

This design guide presents DEVI’s recommendations for design and installation of cable floor heating systems for indoor application.

It provides guidance for heating cable positioning, electrical data and system configurations.

Following DEVI’s recommendations will ensure energy efficient, reliable and maintenance free solution for constant wattage heating cables with 20 year warranty.

1. DEVI electrical heating systems

This document includes all necessary information about DEVI cable heating systems which can be helpful in your decision making during its design, installation and operation. The distinctive feature of DEVI’s profile is production of cable heating systems.

DEVI A/S was founded in in Denmark in 1942 and within over 75 years of its existence it has made the way from a private company to a large industrial enterprise developing and providing solutions for electrical heating cables in more than 100 countries around the world. DEVI takes a leading position as a founder and

an innovator in the field of electrical heating cable systems for indoor and outdoor installation.

Since 2003 DEVI has being a part of the Danfoss Group.

DEVI is the Europe’s largest supplier of electrical floor heating. Our business philosophy is based

on marketing electrical heating solutions that clearly stand out as the following:

Increasing comfort in everyday life;

Greater reliability;

Better design;

Improved operating costs.

DEVI develops, manufactures and sells heating cable systems for the following main applications:

Total electrical floor heating;

Comfort electrical floor heating;

Ice and snow melting on ground – roads, pavements / pedestrian walkways, bridges etc.;

Ice protection and snow melting for roofs and gutters;

Protection against freezing and temperature maintenance of pipelines, tanks and other industrial applications;

Heating of play-fields with natural or artificial grass, soil in greenhouses, etc.;

Heating of agricultural premises;

Frost protection of foundations and floors in cold stores and ice stadiums;

as well as many other heating solutions.

Complete systems

DEVI is the only global company in the industry that develops, produces and markets complete systems containing both heating cables and thermostats in the global market. Consequently, there is a full harmony between the single components that make up our heating systems, which means high performance, optimum reliability and usability and as a result low energy consumption.

Integrated solutions

For almost 75 years DEVI has been producing a wide range of proven tested heating cable solutions – everything from thin heating mat systems mainly intended for renovation purposes, to complete heating systems for room heating in private dwellings as well as offices and industrial buildings. DEVI also supplies ice and snow melting solutions. Our cables and thermostats keep traffic areas, loading ramps and roof constructions safe in cold areas throughout the world. We provide anti-frost systems for pipes and roof gutters and we heat the soil in greenhouses, or even under football fields.

Intelligent heating systems

The main DEVI product is a complete heating system (heating cable or mat, thermostat and accessories).

Energy efficiency and it’s intelligent use is built in DEVI thermostats since the 90’s. Saving up to 30% of electrical bill, compared with an advanced electronic thermostat without a timer, DEVI intelligent thermostats are world leading example to follow in the area of intelligent electrical floor heating.

High quality heating elements manufactured in EU

DEVI heating element is a screened twin or single conductor made with different specific outputs and insulation options. DEVI heating

elements are produced in over thirty different types allowing application of the product that suits best to your specific requirements.

Thin heating mats designed for installation under the tiled floor are most in demand. DEVI mats consist of a thin cable fixed on a composite or glass fiber self-adhesive mesh, which makes mats easy to install and a logical choice for thin floors. When laying heating mats the floor level is virtually the same since installation can be performed with a standard thickness of the tile glue.

System installation and calculation of desired output shall be performed based on specific conditions of premises (application). To ensure proper installation and operation of each DEVI system it is accompanied by multilingual detailed instructions. In addition, most of heating cables and mats have 20 year warranty.

DEVIreg™ Smart, the latest solution, that is worth special attention – it embodies the essence of DEVI commitment to improve user comfort, interaction with intelligent electronic devices, Nordic design and energy efficiency. DEVIreg™ Smart thermostat with:

user-friendly interface via APP and Wi-Fi control,

touchs creen,

intelligent timer functions with an intuitive user-friendly interface which is designed specifically to meet the needs of modern users,

extended warranty period – 5 years.

Reliable choice.

DEVI is the world leader in the production of electrical heating cable systems and is a part of the Danfoss group. Presented in the global market for almost 75 years and available in more than 100 countries on five continents. You can safely recommend products to your clients as far as DEVI trademark has occupied a leading position on the world market and has been a trusted partner for decades.

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2. Application Briefing

2.1 General information

Optimal comfort

All heat moves upwards! This simple fact explains why a floor heating system provides more comfortable heat, than the alternative radiator system. The radiator system provides convective

air movement up to head height and ceiling, only to travel downwards and return as a cold draft around ones feet.

DEVI’s floor heating system, on the other hand, provides pleasant heat for ones feet, body and head.

As it produces only a very gentle upward air movement the amount of travelling dust particles is reduced considerably making the system a great asset to people suffering from allergies or asthma. It also minimizes presence of moisture at floor level.

Minimal energy consumption

Thanks to heat distribution from the floor and precise temperature control system with a DEVIreg™ thermostat, the average room temperature can be reduced by 1-2 °C compared with traditional radiator heating, without influencing the thermal comfort

or even improving it. This enables reducing energy losses, from a dwelling, by 10-20%, which is both economically and environmentally beneficial.

Flexible system

DEVI’s floor heating system ensures comfortable room temperatures, be it at home, at the office, in a workshop, sports hall or virtually anywhere where comfortable heat is required. Equally important is the fact that DEVI’s floor heating system can be installed in all floor types whether they are new concrete or wooden floors or renovated floors.

Invisible heat source

DEVI’s floor heating system is invisible. As the system is hidden under the floor it gives exciting new possibilities for furnishing and interior design and the problem of space-consuming and unattractive radiators (or heaters) no longer has to be considered.

Ease of Installation

DEVI electrical underfloor heating provided as a system, be it a heating mat, cable with installation

accessories or a thermostat with easy setup feature, quick and effortless installation.

High durability, no maintenance

DEVI’s floor heating system has a long life. Practically speaking DEVI’s heating cables and mats last as long as the house where they are installed and no maintenance is required!

Quick and Precise Response Time

Electrical floor heating system has a quick response time. Along with DEVIreg™ intelligent thermostats it also offers precise increase and regulation of room temperature comparing to water based

floor heating systems. System’s responsiveness to temperature changes and user adjustments is also better.

20-year DEVI Warranty™ and Full Service warranty

20-year DEVI Warranty™ is valid for most of DEVI heating mats and heating cables. DEVI support Full

service warranty for cables and mats installed indoor for floor heating – included costs for installation and floor materials such as damage to bricklaying and tiles. Full Service 20-year warranty implies that

when there is a warranty case DEVI undertakes a responsibility to correct the defect free of charge or offer product replacement during the warranty period. In addition, DEVI covers all costs associated with the replacement of any heating system element and floor cover restoration costs.

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3. Product overview

3.1. Cables

Electrical floor heating system consists of two main components:

Heating element (cable, thin heating mat, or heating element for laminate floors, etc.);

Thermostat with air or/and floor temperature sensors.

Heating cables are usually installed in thick/concrete floor constructions. The main feature of a thin heating mat is its low thickness. This gives the possibility for it to be installed in a thin layer of tile glue avoiding considerable increase of floor level.

DEVI heating cable (e.g. DEVIflex™) is designed for installation in thick concrete floor constructions. Usual thickness of top/finish floor layer is at least 3 cm. Heating cables used in floor constructions are serial resistive cables, preferably twin conductor, but also a limited range of single conductor cable is available. Cables are manufactured as ready-to-install

heating elements with specific length (i.e. 7, 10, 15, up to approx. 410 m), with a power supply cable (cold tail) and hermitically closed connections (muffs or end terminations).

Output of heating cables for installation in floor constructions is limited to 20 W/m and DEVI cables are available with 6, 10. 18 and 20 [W/m] for 230 and 400 V. Most DEVI cables are manufactured and approved in accordance with the latest version

of IEC 60800:2009, with mechanical strength class M2 (for rough concrete constructions). The main type of DEVI heating cables for installation in the floor construction is DEVIflex™.

Internal and external design of modern DEVIflex™ cable is shown in the figures below.

 

 

heating cable

 

outer PVC coating

supply cable

 

protective screen foil (Aluminum)

 

 

 

protective conductor

 

 

 

connecting muff

internal insulation ( XLPE)

 

end of the heating cable

 

 

heating element (resistance thread)

 

connection to power supply

DEVIflex™ heating cable construction

 

DEVIflex™ 6T/10T/18T heating cable

3.2 Mats

The thin heating mat is designed for installation in a thin tile glue layer adhesive, self-leveling mixture or alike. The standard minimum thickness of the floor layer is 5-8 mm while the thickness of DEVI mats

is 3-4,5 mm. It allows minimizing the floor level increase. DEVI thin heating mats consist of a thin cable fixed on self-adhesive glass-fiber

mesh usually of 50 cm width. Thin heating cables are serial twin or single conductor resistive cables. Thin heating mats are manufactured as ready-made heating sections with a specific area (i.e. 0,5, 1, 1,5 … 12 m²) including a power supply cable (cold tail) and hermetically sealed connections.

Thin heating mats are available with various outputs, for example: 70 W/ m², 100 W/m², 150 W/m² and 200 W/ m². DEVI thin heating mats comply with IEC 60335-1 & IEC 60335-2-96.

The most commonly used DEVI twin conductor heating mats for installation in the floor construction are DEVImat™ and DEVIcomfort™.

heating cable

adhesive mesh

adhesive mesh

heating cable

connection to

 

power supply

 

 

connection to

 

power supply

connecting muff

connecting muff

supply cable

supply cable

 

DEVImat™ 100T/150T Heating mat

DEVIheat™ 150S Heating mat

6 Division · Cable Floor Heating Systems · VGLUH102 · ©DEVI

Center-to-center distance between mat’s cable lines is usually 7,5 cm. It allows even distribution of heat on the floor surface avoiding cold zones between the cable lines.

The modern thin twin conductor DEVImat™ and single conductor DEVIheat™ are shown below.

DEVI heating cables and thin heating mats mentioned above are the most used floor heating elements. DEVI also produces other floor heating elements, i.e. DEVIdry™ and DEVIcell™ heat distribution panels for heating constructions with wooden surface (laminate, multi-layer boards,

parquet, etc.) or/and on wooden subfloors. DEVIdry™ has 55 and 100 W/m² outputs.

For further information please refer to the DEVI Product Catalogue.

3.3 Thermostats

DEVI offers specialized thermostats for electrical floor heating systems. All thermostats are electronic devices allowing precise control of the

floor surface or air temperatures. In general three types of thermostats are available:

for air/room temperature control and limitation of floor temperatures – with room sensor and floor sensor;

for floor temperature control – with floor sensor only;

for air/room temperature control – with room sensor only.

DEVI offers thermostats that are:

Intelligent, PWM (Pulse Width Modulation regulated)

Simple (hysteresis regulated).

Intelligent thermostats provide state- of-the-art wireless control system for control of heating and electrical units in private houses. Some thermostats are fitted with Wi-Fi allowing remote control of heating systems via mobile application.

Simple thermostats are electronic control units with or without display allowing setting the heating system type, adjustment of control parameters and timer mode.

NEW!!

Adjust your floor heating from your smartphone

DEVIreg™ Smart

DEVIreg™ Smart is the DEVI’s latest solution and a further development of, the very well known DEVIreg™ Touch with Wi-Fi control via mobile application, unique Nordic design and advanced user experience, with application that enables up

to 10 different users to control electrical heating systems from anywhere in the world using a smartphone or a tablet.

DEVIreg™ Smart is an intuitive programmable intelligent timer thermostat used for controlling electrical floor heating elements. The thermostat is designed for flushmount installation into a standard wall installation box, or on wall with a special on-wall box. Due to the special 2-part construction it fits a wide range of frames and sensors.

DEVIreg™ Smart builds further on energy saving functions introduced earlier in DEVIreg™ Touch, like:

fast and intuitive setup using the built-in wizard;

energy-saving program – including optimum start/end control ensuring the desired temperature at the correct time and thereby reducing heating costs;

open window function;

very precise regulation of user set room temperature by means of a specially developed PWM (Pulse Width Modulaton) regulation, including optimal change from comfort to economy mode.

DEVI Link system

covers the control of both radiator heating and

floor heating – individually or combined

DEVIlink™ CC

DEVIlink™ CC (Central Controller) is the central brain in the DEVIlink™ system which includes several wireless DEVIlink™ devices installed inside the building.

Several functions, i.e. room control, intelligent timer, modes for the whole house – “Away”, “Comfort”’, “Frost Protection”, are integrated into the unit to reduce energy consumption when using electrical floor heating system.

The idea of the DEVIlink™ System is to provide wireless connection of your heating system and to control it from one central point. The DEVIlink™ CC communicates wirelessly with

all other DEVIlink™ units of the installation. A single DEVIlink™ CC can control up to 30 rooms and allows connection up to 50 units and specially developed to satisfy the needs of any family house: it can

be also used for apartments, and multifamily buildings.

DEVIlink™ is fitted with Danfoss Link™ App, and the latest version provides the possibility of WiFi control by mobile application, anywhere in the world.

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DEVIreg™ Touch

DEVIreg™ Touch is a thermostat fitted with a display and an intelligent timer. It is designed for flushmount installation into a standard wall installation box. It operates with two sensors – floor wire and built-in room sensor. It allows control setting for one of 3 heating systems: with wire floor temperature sensor, with built-in room sensor or with built-in room sensor and wire floor sensor for limitation of floor temperature. The touch screen menu and intuitive user friendly interface allow easy use and quick service. The thermostat has four original colors – polar white, pure white, ivory and black. It can be installed in complex frames of different manufacturers.

DEVIreg™ Touch is fast and intuitive to setup using the built-in wizard. It has an energy saving program – including optimum start/end control ensuring the desired temperature at the correct time and thereby reducing heating costs.

DEVIreg™ 530

DEVIreg™ 53x series thermostats are designed for flush-mount installation into a standard wall installation box. Three models are available:

DEVIreg™ 530 with wire temperature sensor;

DEVIreg™ 531 with built-in room sensor;

DEVIreg™ 532 with built-in room sensor and wire floor sensor for limitation of floor temperature.

DEVIreg™ 130

DEVIreg™ 13x series thermostats are designed for mounting directly on the wall. Following models are available:

DEVIreg™ 130 with wire temperature sensor;

DEVIreg™ 132 with built-in room sensor and wire floor sensor for limitation of floor temperature.

DEVIreg™ 233

DEVIreg™ 233 is an electronic thermostat designed to be flushmounted in an installation box from the LK FUGA series frame. The thermostat is provided with a single pole switch and a floor sensor (wire) to measure and control the desired floor temperature. Alternatively an

external room sensor can be used, for room temperature regulation.

The thermostat has a button to adjust the temperature setting in the range of (0) 1 to 6.

DEVIreg™ 330

DEVIreg™ 330 (5…45°C) – is an electronic thermostat to be installed in electric cabinets with DIN rail attachment. The set includes wire temperature sensor. To control room temperature an external air sensor is required.

DEVI offers over 20 different types of thermostats. The product range includes easy to operate (by APP) intelligent Wi-Fi control thermostats to specifically designed digital, thermostats with moisture sensors for ice and snow melting on ground as well as ice protection for roofs and gutters (refer to Ice & Snow melting Application Sheet). DEVIlink™ and DEVIreg™ Smart system is equipped with wireless functions and Wi-Fi control of heating systems and indoor electrical equipment.

DEVI provides a unique solution – that is “top quality intelligent heating system”, giving consumers the highest level of comfort and safety! The intelligent component of these systems is the DEVIreg™ electronic thermostat which is available in several options, i.e. for total heating or comfort floor heating.

More information about DEVI thermostats you can find further in this document and in the DEVI Product Catalogue.

8 Division · Cable Floor Heating Systems · VGLUH102 · ©DEVI

4. Heating systems in floor constructions

Electrical floor heating systems for indoor heating can be divided into 3 main heating categories (types):

Comfort floor heating;

Total or Direct heating;

Accumulating heating.

This will be described in details on the following pages.

4.1. Comfort Floor Heating

4.1.1. About the system

Comfort Floor Heating or “Warm Floor” system provides heated floor surface, in any rooms, and especially used for bathrooms and kitchens. Comfort floor heating can be used in any room fitted with another heating system to provide required air temperature, for example water based radiators on the walls. Warm Floor/ Comfort heating installed

in such premises only maintains constant floor temperature at all times, regardless of the heating season. As an additional benefit the Comfort heating increases air

temperature in the room, and due to large heated floor surface will allow compensation of inadequate heating during extremely cold winter days or in case of lack of heat regulation in rooms which are not fitted with

a modern thermostat controlled room heating systems. Comfort floor heating system is controlled by a thermostat with a floor sensor (usually wire sensor). The heating element is activated by a thermostat based on the floor temperature set by the user.

A comfortable floor temperature has been evaluated many times, for example, described in standard ISO/ TS 13732-2. The maximum long term comfort floor surface temperature is defined at the level of 29,5 °C. Additionally: sedentary people needed extra 1-2 °C. For floors in wet rooms maximum temperature can reach 31 °C. These maximum temperature values can be used for calculation and selection of installed outputs (in [W/m²]) of comfort floor heating systems. Different types of floor surfaces need different comfort floor temperatures, e.g. wooden floor surface has an optimal comfort temperature of approximately 26 °C, carpet – approximately 24 °C. But it is impossible to predict type

of floor surfaces during life time of floor construction, as well as that comfort temperature is perceived differently by different individuals. It is advised to use maximum comfort floor temperature level to satisfy all possible options, but often a floor temperature few degrees above the current room temperature will already satisfy the needs of most users. It is important that most of

wooden floor surfaces have limitation of max. temperature at the level of 27 °C (for more details concerning maximum allowed temperatures

of the floor surface please refer to a manufacturer of wooden floor materials).

EXAMPLE:

The optimal required output (in [W/m²]) for comfort floor heating system, can be evaluated by a simple calculation. Assuming that the room temperature is 20 °C (supported by another heating system during the heating season) and the floor surface needs to reach up to 29 °C. The floor temperature must be increased as follows: 29 - 20 = 9 °С. Information about the installed output (in [W/ m²]) needed to heat up 1 m² of

floor surface to 1 °C can be found in physic books and standards (e.g. DS/ EN 1264. Heat exchange coefficient, usually named alfa – α [W/(m²·K)], can vary, however for general evaluation α =10 W/(m²·K) can be used.

Consequently to heat 1 m² of floor up to 9 °С in relation to air temperature, approximately an installation of

9 °С · 10 W/(m²·K) = 90 W/m² is required.

As a “rule of thumb” a safety value of 30% should also be added offering a minimum output for electrical heating element used in comfort floor heating system as calulated in the following example:

90 W/m² · 1,3 ≈ 120 W/m²

Recommendation: output for comfort floor heating systems should be no less than 120 W/m², unless any special restrictions are specified.

The following power outputs for comfort floor heating systems are recommended based on floor constructions, insulation levels,

surface types, room air temperature and individual user preferences:

Wooden floor constructions – no more than 100 W/m²;

Dry rooms, thermal insulated floors – 100 W/m² or more;

Floors without thermal insulation – 130-160 W/m²;

Wet rooms – 150-180 W/m²;

Low voltage, insufficient insulation, covered balcony slabs –

160-200 W/m²;

maximum output in floor construction – should not exceed 200 W/m².

Find more details and restrictions for special floor constructions such as wood, later in this document.

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Comfort floor heating systems do not require heat loss calculation. It is advised to install power at least 100 W/m² in all dry premises, and at least 150 W/m² in wet premises,

however note that norms for wooden floors specify no more than 100 W/ m², and require a thermostat with a floor sensor to limit maximum floor temperature. Heating system must be controlled by thermostat and it is worth mentioning that installation of increased power, e.g. 150 W/m² instead of 100 W/m² does not affect energy consumption of the system, but can influence user comfort feeling.

C-C distance

Heating cables are installed inside floor construction with some distance between them (or so called installation step, centre-centre

or cable-to-cable distance: C-C distance). To achieve a warm floor with even distribution of heat and to provide comfortable temperature on the floor surface, the floor surface temperature variation should not exceed 1,5 °С (e.g. DIN 44576). There will always be a difference in temperature on the floor surface, in areas between heating cables and directly above them. The bigger C-C distance – thicker layer of concrete above cable is necessary to ensure

a uniform/comfort temperature distribution along the floor surface. This difference is always more pronounced during periods, when electrical heating cables are turned on (providing heat to the floor heating). The instant thermostat disconnects the heating cables, because desired floor temperature is reached, the temperature on the top of the floor surface is equalized greatly, giving an increasingly comfortable floor surface.

A rule of thumb indicates:

The thickness of concrete & floor structure above the heating cables need to be ~½ the C-C distance.

Here is the additional explanation:

For Warm Floor system installed into a thick concrete slab the C-C distance of 5-10 cm is

recommended. The thickness of the concrete slab top layer is usually

not less than 3-5 cm, regardless whether heating cables are to be installed there or not. For thin floor constructions, such as tile glue, laminate etc., the C-C distance should not exceed 10 cm and is recommended to be even less: 7,5 cm. To install heating cables under the tile glue the best solution is DEVI thin heating mats with

C-C = 7,5 cm that guarantees floor surface without cold zones.

Recommendation: it is always advised to insulate the floor structure below the heating cables.

More details about cable installation step (C-C distance) and appropriate outputs are described below in this document.

Thermostat with floor sensor:

The thermostat uses a wire sensor to measure the temperature inside the floor construction. The sensor needs to be placed directly between, and if possible, slightly above the lines of a heating cable or a mat. Temperature measured by the floor sensor is

not the real surface temperature and depends on placement of the floor sensor. It is difficult to give any recommendations about the

thermostat settings for a specific floor construction.

The thermostat with a floor sensor has a scale without degree marking.

4.1.2. System Design

Following stages will help you to find a right solution for your comfort floor heating system (more about DEVI products find in the DEVI Product Catalogue):

Choice of a heating element type (mat or cable).

Define the thickness of floor construction over the cable, and a type of the installation. For example for renovation, where small floor structure needs to be enlarged, a heating mat is a preferable solution due to the element’s height.

If you plan to increase the floor construction by less than 30 mm, it’s preferred to use a heating mat, suitable for floor increase of 3-5 mm.

If you plan to increase the floor construction by more than 30 mm, a heating cable is usually applied. It should be noted that there are no restrictions for use of heating mats in concrete or thick floor constructions. The question of thermal insulation, installation

thickness in floor construction should also be addressed, as it’s important to minimize heat losses downwards.

Choice of specific output.

Specific output (p in [W/m²]), for Comfort Floor Heating usually does not require calculation and is selected from recommendations for specific floor construction and environment. For standard floors without insulation the output of no less than 100 W/m² is usually chosen and for wet rooms – no less than 150 W/m². In the lack of reliable information about the floor construction, flooring type, supply voltage, etc., it is better to choose

an output as close as possible to the maximum recommended (see page above).

To fix heating cables DEVIfast™ fitting bands are usually applied, it offers

a cable attachments with a step distance (C-C) of 2,5 cm.

This leads to the situation that the value of the specific output for a heating cable cannot be chosen arbitrarily, and it should be taken into consideration that the cable can be installed at 2,5 cm intervals only, and respectively output will match attachment distance.

For example if:

cable is DEVIflex™ 18T,

supply voltage is 230 V,

the C-C distance of 12,5 cm gives output of 145 W/m².

And for installation step with the C-C of 10 cm – 180 W/m² (see the DEVI Product Catalogue for product selection). Thereby, for heated area

the value of the specific output - pINST [W/m²[, which is actually installed,

should be chosen for fixed C-C, following the table or calculated value.

It should be noted that in some countries the supply voltage is lower than 230 V that leads to decrease

of the cable specific output and respectively, different [W/m²] with

10 Division · Cable Floor Heating Systems · VGLUH102 · ©DEVI

the same step (C-C). For example, if the given output is 230 V the

coefficient of 0,915 should be applied with 220 V supply.

Estimation of heated floor area.

Installation area of heating cable/mat

has to be calculated AINST [m²]. To do this, from the total area of the room

(in [m²]), the area under stationary objects (bath, toilet, shower, cabinet, cupboards, etc.) and a strip of free floor along walls (usually 10-15 cm wide) is deducted, as well as special customer’s preferences should be taken into account.

The heating cable or mat is set into the floor for many years, so it’s

advised to exclude from heated area items/furniture that can be moved over the operation life of the premises: cupboards, cabinets, bed etc.

Along the interior walls, where any furniture most probably will be located up to 30-40 cm can be

allowed. For heating systems installed in the floor construction, furniture on legs, that provide air circulation underneath is recommended.

Choice of a specific heating element (length of heating cable or area of heating mat).

Heating cable is normally chosen based on required heating output for room (the calculated total output

PCALC [W]). This output is calculated as the chosen specific output

PINST [W/m²] multiplied by the installa-

tion area AINST [m2]:

PCALC [W] = PINST [W/m²] · AINST [m²]. The heating element is selected from the

product list of factory-produced ele-

ments, with specific output PINST [W]. Always the product nearest to, but

larger than, calculated total output

PCALC [W], is to be chosen. For indoor heating DEVI recommends to use

screened twin conductor DEVIflex™ 18T, DEVIflex™ 10T, DEVIflex™ 6T heating cables or if nothing else is suitable, a screened single conductor DEVIbasic™ 20S heating cable.

The number at the end of the cable’s name refers to: its specific output for 1 m in [W/m] at 230 V, and letter “T” means a twin conductor cable (Twin), letter “S” - single conductor cable (Single).

The most frequently used cable type is DEVIflex™ 18T – twin conductor, 18 W/m at 230 V (16,5 W/m at 220 V). A linear output of DEVIbasic™ of

20 W/m, is not the best choice for even temperature distribution along the floor construction, if installed in the same floor, compared to DEVIflex™ 6,10 or 18 W/m.

The heating mat is selected from a range of factory-produced elements (covering area from 0,5 to 12 m²), with an area covering usually the nearest less value to available installation space AINST [m²]. If the installation area (AINST [m²]) exceeds 12 m², a multiplication of chosen heating mats needs to be applied.

For example, DEVI screened heating mats designed for floor installation have the cable/mat thickness for:

twin conductor of ~3,0 mm: DEVImat™ 70T, DEVImat™ 100T, DEVImat™ 150T, DEVImat™ 200T;

twin conductor of ~4,0 mm: DEVIcomfort™ 100T, DEVIcomfort™ 150T;

single conductor of ~3,0 mm: DEVIheat™ 100S or DEVIheat™ 150S.

The number at the end of a mat’s name refers to its specific output for 1 m² in [W/m²] at 230 V, and letter “T” means twin conductor mat (Twin), letter “S” a single conductor mat (Single). A single conductor heating mat requires more planning before installation, to ensure that the power supply cord attached to both ends of the heating mat starts and ends at the same place.

For Comfort Floor Heating

DEVImat™ 150T and DEVIcomfort™ 150T heating mats are used most often – twin conductor, 150 W/m² at 230 V (135 W/m² for 220 V).

Calculation of the fitting band length (DEVIfast™).

If heating cable is applied, it is recommended to use fitting band to fix it to the floor base. For example, metal galvanized DEVIfast™ fitting band. It is attached to the floor (nailed or fixed with screws or glued) in parallel lines, usually every 50 cm.

This equals to two (2) meters of band for each square meter [m²] of cable installation.

Simple calculation of the fitting band length LFIX (m): cable installation space is multiplied by two, e.g.

LFIX = SINST · 2 (m).

Thermostat selection.

Thermostat for Comfort Floor Heating system should be fitted with a floor temperature sensor.

Choice recommendations: heating area is larger than 5 m² – programmable thermostat with timer, for example, DEVIreg™ Smart; smaller than 5 m² – simple one without a timer, for example, DEVIreg™ 530 or DEVIreg™ 130, can be chosen. Simple thermostats are only recommended due to their lower cost, and as there are no

restrictions for use of thermostat with timer for small areas.

The maximum output (in Amperes), that thermostat is able to switch on usually varies between 3450-3600 W (15-16 A). This needs to be taken into consideration for larger rooms. If more than maximum 3450-3600 W is needed the following two solutions are possible:

1.Heating area is divided into independent zones with separate cables and individual thermostats. Each zone not exceeding the connected output indicated above, and with the same output (in [W/m²]) installed;

2.Contactor (additional relay) with increased maximum current is used (e.g. 20 A or more), usually mounted on a DIN rail in the electrical switchboard.

Recommendation: it is advised to choose thermostat load of 70-80% of maximum installed output.

Choice of additional equipment.

Mounting box for thermostat, conduit pipe for floor temperature sensor, screws, nails or anchors for attaching fitting band to the floor, etc.

It is assumed that the voltage supply is stable and properly connected,

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according to electrical laws of the country of installation e.g. fuse and RCD (Residual Current Device) are installed in switchboard, section and length and cross section area

of power supply cable are properly chosen. Otherwise these elements have to be selected too.

Floor construction.

Follow installation instructions provided by manufacturers of floor elements, and local building regulations.

4.1.3 Design Example. Calculation and selection of equipment

Comfort floor heating for

Installed output.

bathroom.

Wet room, stable voltage, 2-nd floor,

Input data: bathroom, 2nd floor (over

tiles, heated room below: an output

heated room), no floor insulation,

of 150-180 W/m² (chapter 4.1.1) is

size 3 x 4 m, total area of 12 m², with

recommended.

installed 0,9 х 1,7 m bathtub, stable

 

power supply voltage of 230 V, floor

Calculation of heated floor space

surface made of tiles.

(area of cable installation).

Restrictions for the floor height: can

Out of the total space A (in [m²])

be increased maximum by 2 cm.

bathtub area (0,9 х 1,7 m) and strips

 

of floor of 10 cm along the walls are

Heating mat or cable?

subtracted:

Since the floor height is an issue

AINST = 12 m² – (0,9 m · 1,7 m) – ((3 m + 4 m) +

the concrete thickness is less than

+ (3 m – 0,9 m) + (4 m – 1,7 m)) · 0,1 m =

3 cm. Choose a mat, DEVImat™

= 12 m² – 1,53 m² – 1,14 m² ≈

or DEVIcomfort™ twin conductor

≈ 9,33 m².

screened mat (find a detailed

 

description of products in the

Select the desired mat size.

DEVI Product Catalogue).

Available floor area is 9,33 m².

 

DEVImat™ 150T covering 9 m² of

 

floor, and with total output of 1235 W

 

at 230 V, is chosen.

If the mat covering 10 m² of floor is chosen, there will be a surplus of 0,67 m² of mat, and since it’s not allowed to cut or shorten a heating cables and mats, the mat covering 9 m² of floor is a preferred choice.

Fitting band.

It is not needed, since DEVImat™ has a self-adhesive glue on the underside. We advise to clean the floor and remove all debris and dust.

Thermostat selection.

DEVImat™ 150T with 1235 W output, less than 34503680 W maximum allowed, can be connected to a DEVI thermostat. For the heating area exceeding 5 m² – thermostat with a timer is recommended. For example, choose the most modern programmable WiFi thermostat with intelligent timer – DEVIreg™ Smart.

Type

System

Temperature sensor

Range

IP class

Load, max.

 

 

 

 

 

 

DEVIreg™

Programmable:

Air: embedded,

Floor 5…45 °С.

IP21

3680 W

Smart

Comfort Floor Heating or Heating

Floor: included wire

Air 5…35 °С

 

 

 

 

 

 

with floor temperature limiting

sensor

 

 

 

 

 

 

 

 

 

As an option, simple thermostat with floor sensor can be chosen: e.g. DEVIreg™ 530. When thermostat is installed in a wet room, the requirements of electrical safety norms and corresponding IP

class should be strictly followed! It is recommended to install the thermostat outside the bathroom.

Additional equipment.

Electrical materials necessary for installation will typically include the following: wall mounting box for thermostat, 4-5 m conduit pipe for a floor temperature sensor and

additional power supply if necessary. It is assumed that there is a proper power supply, according to the rules

and regulations for safety elements of electrical installation, e.g. fuse and RCD are installed.

Summary:

For comfortably warm floor in 12 m² bathroom (with free area of 9,33 m²), the following DEVI floor system elements are recommended:

Equipment

Characteristics

Quantity

 

 

 

Twin conductor screened DEVImat™ 150T

9 m² 1235 W (at 230 V), (150 W/m²)

1 pcs.

heating mat

 

 

DEVIreg™ Smart thermostat

Programmable, WiFi, APP enabled, intelligent timer,

1 pcs.

 

air and floor sensors, IP21

 

 

 

 

Conduit pipe

Ø 16

4 m

 

 

 

Mounting box

 

1 pcs.

12 Division · Cable Floor Heating Systems · VGLUH102 · ©DEVI

 

4

2,3

1,7

0,1

 

 

<![if ! IE]>

<![endif]>0,9

<![if ! IE]>

<![endif]>3

 

Temperature sensor in corrugated pipe

 

End mu

0,5

0,075

Connection mu

C-C distance

Thermostat

 

Figure 1 – Example of heating mat installation in bathroom. All distances are in [m].

4.2. Total (Direct) floor heating

4.2.1. About the system

Total or Direct electrical floor heating is the only heating system installed in a room (or area) for maintaining a user specified room temperature. It is ensured by adjusting floor surface temperature, due to the changeable heat transfer from the surface of

the floor. Such a system is regulated by a thermostat with air & floor or only room temperature sensor. Air room sensor is an integrated part of DEVIreg™ room thermostats. A floor heating system has a large heated surface of the floor, and it is a convection and radiation heating

system. Advantage of a floor heating system is to provide heat in the lower part of a room near legs and relatively less heat around room ceiling, where it’s not so highly needed. It is proven by many studies,

that such temperature division is the most comfortable for any person, independent of gender, age and activity level. Floor heating system provides a feeling of the same or improved thermal comfort at lower overall room temperature setting.

As a result, it can be lowered by app. 1...2 °C, compared with an earlier used radiator heating system, with heating element installed visibly under the window. This provides a user with improved thermal comfort and energy savings of approximately 10-20%.

Output of a heating system is chosen based on the level of calculated heat loss (in Watts). Energy, which is provided via a floor heating system, must cover heat loss and support

a specified air (room) temperature.

Usually a safety factor of 20-30% is added to the heat loss calculated output value, depending on room’s specific thermal condition. As the heating system is controlled by a thermostat, installing larger power output does not affect the overall consumption of electrical energy for heating.

Total electrical floor heating, “Heating via floor” should not be confused with “Comfort Floor Heating/Warm Floor”. The need for warmth is variable, because of the changing outside temperatures during the heating period, and accordingly floor temperatures varies too. As

an example, in October, when the outside temperature is +5 °C, it would be enough to heat the floor up to 21...22 °C to maintain indoor temperature of 20 °C. But in February,

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when the outside temperature is lower e.g. -15 °C, floor will be heated more e.g. 25...26 °C, to maintain the same room temperature.

When utilizing floor heating system for total heating you should always choose as technically correct solution, but observe the limitation of the maximum floor temperature. For regulation of a total heating system a thermostat measuring

air (room) temperature and fitted with floor temperature sensor is the preferred choice. Allowing setting maximum floor temperature level and constantly monitoring prevents overheating of floor. Such limitations are strictly necessary for floors with wooden surface.

Special DEVI thermostats are used where setting of the maximum floor temperature is necessary or advisable:

in programmable models: by setting of special option.

in simple models: by manual potentiometer under the thermostats cover.

Factory default setting for maximum floor temperature limit is 35 °C.

Even if a specific floor installation doesn’t particularly require a floor sensor to be installed, it’s strongly advised to do so. Install a plastic pipe conduit where, at later date, floor sensor could be fitted. The heating element (cable or mat), is installed in the floor construction where it forms parallel lines. When using a heating cable: output density of heating system (in [W/m²]) is determined

by C-C distance (cable-to-cable or center-to-center distance) of heating cable. Increasing the distance between cables leads to decreasing of output and vice versa. When a

desired output density is calculated and chosen, than C-C distance, that will determine the number of cable lines per 1 m² of floor or the cable length per 1 m² is calculated.

Multiplying the chosen cable length on a total area of heating cable installation will give the calculated length of heating cable.

C-C distance (cm) =

=

Available floor area (m²) · 100 (cm/m)

 

Length of chosen cable (m)

Detailed information about cable installation procedure is found later in this document.

For modern houses or dwellings calculated heat loss is small and, consequently, the output of floor heating system is also limited. As a result, to prevent a heating cable from being installed with a large C-C distance, it’s advisable to use one with less linear output. For example, for calculated heat loss of 50 W/m², when using the most common DEVI cable: DEVIflex™ 18T, the C-C distance will be as big as 36 cm. That will inevitably lead to a floor surface pitted with cold zones situated

between lines of the installed heating cable. As aim for a floor heating system is to achieve and maintain

a constant and comfortable floor temperature, for heating systems with required low specific output, we recommend heating cables with lower linear output (in [W/m²]): for example DEVIflex™ 10T or DEVIflex™ 6T. This allows reduction of C-C

distance and leads to a more even temperature division on the floor.

Safety coefficient.

For heating systems installed in floor structure, it’s necessary to add a safety coefficient of 1,2-1,3, when designing a power output that needs to be installed in the floor. This factor is an experience value used by the industry, and is based on following facts:

heating cables length, resistance and wattage tolerance,

power supply voltage has some accuracy,

heat loss downwards, floor buildup, and surface material type.

Floor surface temperature.

It should be taken into account that

the big heat loss leads to necessity of big output from a heating system and, accordingly, to high and perhaps not a comfortable temperature on the surface of the floor. The maximum temperatures of the floor surface for different types of applications are specified in the relevant standards. For a rough estimation of the possible floor temperature for a given output the

value of heat exchange coefficient of α =10 W/(m²·K) (more description is found in paragraph about Comfort floor heating) should be used. For example, if the output of the heating system is 150 W/m² and heat loss down is ~ 20%, than the heat flow up is 150 – (150 · 20%) = 120 W/m².

If actual heat loss is close to that value, it will imply a requirement of an increase of a floor surface temperature with as much as 12 °C (120 W/m² /10 W/(m²·K) in relation to air temperature. E.g. if the air/ room temperature is 18 °C, the floor

temperature can reach 18 + 12 = 30 °C in the coldest time of the year to satisfy the rooms actual heat loss.

4.2.2. Calculation and selection of elements/products

For more detailed information refer to the DEVI Product Catalogue and previous chapters of this document.

Estimation of a heating system’s calculated output.

Define heat loss of the premises Q [W]: from documentation or by calculation (e.g. EN 12831).

Floor heating system calculated output is determined with taking into account a safety factor of 1,3:

P = Q · 1,3 [W].

Choice of a specific heating element (mat or cable).

Define the thickness of floor construction over the cable. If planned concrete height is 3 cm or more, heating cable is usually

installed, if floor construction is thin (tile adhesive, etc.), heating mat (with thickness of ~ 3-4,5 mm) is a preferred choice. It should be noted that there are no restrictions for use of heating mat in concrete or thick floor construction.

14 Division · Cable Floor Heating Systems · VGLUH102 · ©DEVI

It’s strongly advised to install insulation in the floor construction if possible. Its thickness should be selected according to local norms. When heating system works for a fairly long period during the year (e.g. in the Nordic countries for 6-8 months per year), thickness of

thermal insulation in the floor has a direct influence on level of heat loss and therefore additional electricity costs. For the durability of the floor construction concrete installed over/onto insulation, has to have

a thickness of at least 3 cm and be in accordance with local building norms.

Estimation of heated floor area.

To estimate installation area of

heating cable or mat AINST (in [m²]): deduct the area, where cable is not

installed, from the total area of the installation (room). It’s recommended that strip along the walls without cable/mat has width of ~ 10-15 cm and along the interior walls, where furniture will be most probably installed, is within 30-40 cm.

For heating systems in the floor construction, furniture on legs (min. 5 cm of air gap to the floor) is

advised, allowing airflow underneath, so the cable/mat under the furniture will not overheat.

Estimation of the calculated output per [m²].

Specific calculated area output, pCALC [W/m²] is calculated by dividing the calculated heat loss Q [W] by the installation area AINST [m²]:

pCALC = Q / AINST [W/m²].

It should be noted that the calculated output is typically slightly less than real chosen output of heating cable, which is installed in the floor. This

is due to the fact that cable can be attached on DEVIfast™ fitting band with a fixed distance of 2,5 cm (or multiplication thereof) only.

Choice of length of heating cable or area of heating mat.

Total cable/mat output should not be less than the calculated heat loss, including the safety factor of 1,3.

Heating cable.

Cable is usually fixed with help of DEVIfast™ metal fitting band, with cable attachment points every 2,5 cm and allows to implement different fixed output on 1 [m²]. This fact should be taken into consideration during calculation of a specific solution. For example, if the cable is DEVIflex™ 18T and supply voltage

is 230 V for C-C distance of 12,5 cm, output is 145 [W/m²], and for

C-C = 10 cm – 180 [W/m²] (See also Appendix A.1).

It should be noted that in some countries supply voltage is lower than 230 V, which leads to a decrease in cable output and, respectively, different [W/m²] with the same installation distance. For example

at 220 V electrical supply, the output form a heating element, rated at 230 V is only 91,5% (coefficient 0,915 should be applied to heating element output from DEVI Product Catalogue).

For heating cable with defined installation C-C distance, a specific output pINST [W/m²] is selected, with help of a product table or

calculated using the formula. Usually a product with nearest larger value to calculated output pCALC is chosen. This chosen/calculated output will be the actual output for 1 m² of the heating system. In other words, it is area specific output pINST [W/m²] of selected heating cable installation C-C distance.

Heating cable total output pCALC [W] is calculated as the specific output pINST [W/m²] multiplied by the installation area AINST [m²]:

pCALC [W] = pINST [W/m²] · AINST [m²]

Cable is selected from a list of factory produced products, with output

pINST [W], usually the nearest larger to calculated output pCALC [W]. The nearest lower output can only be

recommended, if it differs from the estimated no more than ~5%.

Output of the selected cable is the actual output of the heating system.

For total room heating DEVI recommends to choose screened twin conductor DEVIflex™ 18T, DEVIflex™ 10T, DEVIflex™ 6T heating cables or, only if necessary, a single conductor DEVIbasic™ 20S heating cable.

The number at the end of the cable’s name refers to its specific output for 1 m – W/m at 230 V, letter T – twin conductor cable (Twin), letter S – single conductor cable (Single).

In floor construction the most frequently used cable is DEVIflex™ 18T – twin conductor, 18 W/m at 230 V.

Heating mat.

When installing thin heating mat, it is chosen with a specific output pINST [W/m²] the nearest larger to calculated output pCALC. However installation also needs to look at the available floor area AINST [m²], and choose a mat, that covers an area close to available. Otherwise installation will leave unheated and cold floor areas, resulting in users dissatisfaction with the total heating system.

For example, DEVI screened heating mats designed for installation in floor construction:

twin conductor of ~3,0 mm: DEVImat™ 70T, DEVImat™ 100T, DEVImat™ 150T, DEVImat™ 200T;

twin conductor of ~4,0 mm: DEVIcomfort™ 100T, DEVIcomfort™ 150T;

single conductor of ~3,0 mm: DEVIheat™ 150S.

The number at the end of the mat’s name refers to its specific output for 1 m2 in [W/m²] at 230 V, letter T – twin conductor mat (Twin), letter S – single conductor mat (Single).

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For example, DEVIcomfort™ 100T heating mat is a twin conductor, 100 W/m² at 230 V (91 W/m² at 220 V).

Output of the selected heating mat will be the actual output of the heating system.

Calculation of the length of the fitting band.

If heating cable is chosen, it is recommended to use fitting band to fasten it to the floor base, for example, galvanized DEVIfast™ fitting band. DEVIfast™ is usually attached to the floor (screwed, nailed or glued) in parallel lines spaced every 50 cm, but not more than 1 m. As a result, approximately two meters of band for each square meter of installation area are used.

Calculation of fitting band length LFIX (m) - cable installation area is multiplied by two:

LFIX = ASINST · 2 [m].

Alternatively, if installation allows, heating cable can be fixed to metal reinforcement mesh placed in the floor construction with help of DEVIclip™ twist.

Choose a thermostat.

Thermostat designed for electrical floor heating system for total heating is fitted with an internal air temperature sensor and usually with an additional floor

temperature sensor (included with thermostat). The floor sensor allows controlling and limiting the maximum temperature of the floor surface. This restriction is often mandatory and standardized for some producers of floor coverings,

e.g. for laminate or parquet boards.

Following is recommended, if:

heating area is larger than 5 m²: programmable thermostat with timer, for example, DEVIreg™ Smart or DEVIreg™ Touch

heating areas is smaller than 5 m²: simple thermostat without timer, for example, DEVIreg™ 532 or DEVIreg™ 132, can be chosen.

Simpler thermostats are only recommended in terms of their lower cost. But for heating system thermostats with timer are the most energy-efficient choice, since there is a possibility to save energy during the absence of people in the room, e.g. reduce temperature in the room at night.

Thermostats have an internal relay that has a limitation of the maximum output (Amperes), that thermostat can switch on: typically 3450-3680 W (15-16 A).

In case of need to install more than maximum 3450-3600 W, following two solutions are possible:

1. Heating area is divided into

independent zones with separate cables and individual thermostats, each zone not exceeding the connected output indicated above, and with the same output (in [W/m²]) installed;

2.Contactor for proper current isused (additional larger relay), usually mounted on a DIN rail in the switch panel.

Recommendation: it is better to choose thermostat load at 70-80% of maximum.

Choice of additional equipment.

Mounting box for thermostat, conduit pipe for floor temperature sensor, nails or anchors for attaching fitting band to the floor, etc.

It is assumed that the voltage properly supplies the place of the thermostat installation, e.g. fuse and RCD are installed in

switchboard, section and length of power cable are properly chosen, etc. Otherwise these elements have to be selected too.

Floor construction.

In multi-layer floor construction, consisting of many elements, a wide range of considerations need to be made. Always follow the national rules for construction and in case of uncertainty get in contact with your local DEVI product supplier.

Example. Direct Floor Heating – calculation and selection of equipment

Total heating system for new build living room.

Total heating via electrical floor, using the heating cable including limiting of maximum floor temperature.

Data:

Room size 3 x 5 m, total area of 15 m², concrete floor, stable supply voltage 230 V, ground floor, concrete is assumed more than 3 cm thick, calculated heat loss is 1100 W.

Definition of cable system’s calculated output.

The calculated heat loss Q is 1100 W or per [m²]: 73,3 W/m². To select cable heating systems take into account the safety factor of 1,3, the calculated output is: P = 1100 · 1,3 = 1430 [W].

Choice: heating mat or cable.

Concrete is assumed not less than 3 cm thick, floor construction is “thick”. Twin conductor screened DEVIflex™ 18T heating cable is chosen for installation.

It is assumed that insulation of necessary thickness will be laid under the cable, so downward heat loss is minimal and does not require taking into account.

Estimation of heating cable or mat installation area.

It is proposed that the cable is placed at a distance of 10 cm (0,1 m) from the 3 m length outer wall and the same from opposite wall with the door. There are no other permanent

(fixed) installations in the room, limiting the availability of the floor area. Under these assumptions for 3 x 5 m room the area for cable installation is:

AINST = 15 m² – (3 + 5 m) ∙ 0,1 m –

– (5 + 3 m) ∙ 0,8 m =

=15 m² – 0,6 m² – 3,2 m² =

=11 m²

4.Estimation of the calculated output per 1 m².

The calculated heat loss Q [W] should be divided into cable installation area

AINST [m²]:

pCALC = Q / AINST = 1430 W/11 m² = = 130,3 ≈ 131 W/m².

16 Division · Cable Floor Heating Systems · VGLUH102 · ©DEVI

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