Floor Heating

VärmeKabelTeknik Floor heating

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Floor heating VärmeKabelTeknik 2

Why floor heating?

If one wishes to feel really comfortable, the best way is to ensure that the floor is somewhat warmer than the rest of the room. It is a fact that one feels better when the feet are warmer than the rest of the body. Velox Floor heating system does this and thus provides greater comfort.

How does Velox floor heating operate?

Velox is an electrical heating system employing cables as the heat generation source. The cables are installed in the floor in such a way that the requisite power is easily obtained, and the warmth simply controlled by room thermostats.

Heat is generated in two ways, by radiation and convection. Floor heating gives a greater surface area of radiation than convection. This allows a greater degree of warmth and comfort, with simplicity of control.

How about energy consumption?

The difference between the air room surfaces ‐ walls, floor and ceiling ‐ determines the heat supply. As warm air rises, the floor is normally the coolest part of the room. The feet act as a sensor, and when feeling cold the tendency is to increase the temperature. With an increase in air temperature there is an increase in energy consumption. With floor heating the feet are comfortably warm and the air temperature and energy consumption are reduced. There is thus a considerable saving over conventional heating, both in energy and cost.

By reducing the air temperature by one degree centigrade, energy saving of some 6% can be achieved.


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Domestic areas

When the feet are warm one is unlikely to be cold. In the bathroom a heated floor is the acme of comfort.

In other rooms, floor heating is also to be recommended for overall comfort and energy saving.

With floor heating maximum space is possible, as wall radiators are unnecessary. Moreover, there is the further advantage of protection against fire as the heating cables are fully concealed.

Community areas

In schools, nurseries and similar areas where children predominate, there is a great deal of floor level activity and in such circumstances; floor heating has much to commend it. In wet weather it is a great asset as floors dry quickly, allowing children to play without interruption. It also ensures that the under‐soil remains dry and gives protection against damp spots and mould.


In living rooms, floor heating permits a relatively low temperature to be maintained without affecting the overall ambience, again, showing big savings in energy consumption and cost. There is no need for the provision and maintenance of wall radiators with a resultant saving in costs and floor and wall space.

Industrial premises

Underfloor heating, resulting in warm feet and cool head allows for far better working conditions.

This is particularly so when working at or near floor levels, and dry floors substantially reduce the risk of industrial accidents.

Concealment of the heating source is an aid to the environment, allowing the maximum use of floor space and facilitating the installation to partitioning such as the required for open‐plan offices.


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Types of cables are TCPR and BTL Floorheat.

The TCPR is an armoured series conductor cable with return wire. This cable is easy and quick to install only having one connection at the control point. The cable is custom‐made by us and is delivered both with cold‐lead‐in cable connections and end terminations.

Read about BLT‐Floorheat on page 7..

FORE MORE DETAILED DATA, SEE CHAPTER "H" CABLE DATA

Application of heating cable in concrete:

One position casting: the heating cable is laid directly on the armament. The heating cable is fitted in place with the electrical tape or plastic binder.

Two positions casting: the heating cable is fitted with special hose clamps which are mounted on the concrete. The distance between the hose clamps should be approx. 1 metre. The hose clamps are mounted crosswise the planned heating cable installation.


BTL FLOORHEAT

Universal floor heating cable ‐ type of cable = self‐limiting

Floor heating cable for all‐round use!

Floorheat heating cable ‐ the cable which is suitable for all types of floors.

Which type of ground?

Floorheat is self‐limiting which means that you can install the cable directly against the ground even if it is combustible (wood, plastic, carpet etc.).

Where do you install the cable?

Floorheat can be used for casting in concrete floor and is then laid with a c/c‐distance of 15‐20cm or in levelling compound with a c/c‐distance of 10‐12cm (to keep an even temperature over the whole floor).

The heating cable is glued against the flat ground or is to be clenched against the armament at casting.

How to order floorheat

Floorheat is ordered as running metre in required length or on drum in order to be kept in stock together with assembling kits. You do not need to go out to the customer to make a control measurement of the surface and then order the cable. Begin with the end connection directly on the drum, reel out the cable and cut when the floor is laid with cable in required c/c‐distance. Then you finish with shrinking tube and the work is complete.

What type of control is required?

Due to the self‐limiting qualities of Floorheat, the application can be controlled by a room thermostat but we recommend a thermostat with floor sensor to achieve the best comfort. Floorheat is automatically limiting the temperature on the floor even if covering is made. An advantage is if some part of the floor requires extra heat, for example under windows, at outer doors or where the floor is wet, the cable increase the power automatically in order to compensate this locally.

Is this working in reality?

Floorheat were introduced on the market 1988 and since that has approx. 200.000 metre been sold especially to boat building yards for floor heating in toilets and shower rooms with good experiences.

Power dimensioning

Power table

Power/m² Cable/m² C/C‐Distance

50 5 meter 20.0 cm

60 6 meter 16.5 cm

70 7 meter 14.5 cm

80 8 meter 12.5 cm

90 9 meter 11.0 cm

100 10 meter 10.0 cm

Power stated at a floor temperature of +25°C.

Installation

The installation will be easy since the only thing you have to take into consideration is to distribute the cable evenly over the floor according to the table above.

To small c/c‐distances does not effect the floor temperature, the construction of the cable is such that not even if the cable cross itself causes any deterioration of the application.

No measurable magnetical and electrical fields


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Installation of heating cable in wooden floors:

Please observe the following basic principles when applying heating cables in wooden floors:

‐ The sheath temperature must not exceed 80°C.

‐ The cable must not be applied to a direct contact with combustible materials.

‐ The cable must not be applied directly on the insulation material.

These principles are met when:

‐ The power per metre cable is limited to 15 W/m.

‐ The power per m² floor surface is limited to 80 W/m2

‐ If the distance between the two surfaces (floor/ceiling) is at least 30mm.

If special mounting plates are used when joists are to be crossed.

Wooden floors not ground floors?

The best bedding for the cable is a fine‐meshed chicken wire. The net should be spaced between the joists in order to get a distance of at least 30mm between the cable and underneath the floor. The heating cable is applied to the net by cutting stitches and then folding them over the cable to fix it in its position.

The cable applied to the joists parallel and not closer than 50mm. You have to make cuts in the joists where the cable is to cross and then attach the mounting plates.

Please note! ‐ Try to reduce the cuts to a minimum.


General instructions

Begin the installation from the junction box and apply the cable in accordance with the design.

Reel out the cable to its full length before it is fixed into position.

The cable is to be applied on the free floor area and not beneath fixed cupboards etc, where the floor cannot allow heat to the room. To allow for downdraft, the heating cable should be installed with a closer c/c‐distance along the outside walls. This enables a greater output to be obtained.

Normally only one heating cable length is installed in each room and with its own switch/thermostat.

The heating cable lengths are controlled by a thermostat. The sensor is placed in a protective tube in the floor between two cable runs. When placing the sensor possible incoming heat radiation must be taken into consideration. The basic rule is to place the sensor inn the floor in such a way that the heat radiation has very little influence. Then the sensor can be placed "high up" in the floor. If it is necessary to put the sensor where the sun shines on the upper floor surface the sensor must be placed "low down" in the floor.

Installation

When the cable is installed and before the floor is finally laid a competent electrician always has to check:

• The resistance of the cable (see marking label)

• The insulation resistance of the cable (mega test min 50 MΩ)

For further information please do not hesitate to contact VärmeKabelTeknik who are always ready to assist.

Placing of sensor at sun radiation (from south and west)


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Dimensioning floor heating (power calculation)

When calculating the heat requirement for a floor heating installation you use the same method of calculating as for other heat sources. In average, well insulated houses with a ceiling height of 2.4 ‐ 2.7m and with double‐glazed windows an adequate heating is usually obtained, even during cold winter days, with an installed power of 70‐100W/m² floor surface. The exact heat requirement is depending on the geographic location.

Power required Watt/m² (Guiding principles).

Type of room Lowest outdoor temperature

‐ 20°C ‐ 30°C ‐ 40°C

Living rooms 60 ‐ 90 80 ‐ 110 90 ‐ 120

Halls and entrancies 70 ‐ 120 90 ‐ 130 100 ‐ 140

Bath‐/shower rooms 90 ‐ 140 100 ‐ 150 110 ‐ 150

Garages 60 ‐ 80 70 ‐ 90 90 ‐ 110

Offices and shops 90 ‐ 100 ‐ 110 ‐

Floor temperature:

The maximum over temperature compared to the air temperature that the floor can take (T

gö) is calculated as

per below:

Tgö = 0,07 x power installed/m2.

Example: Power installed 80 W/m2 Tgö = 5,6 °C.

Studies and experience show that temperatures up to 28°C the floor feels pleasant. With floor heating the temperature should not exceed 28°C.

Higher temperatures can be allowed in places where people stay only a short while, for example in bathrooms.

Flooring materials

Most types of flooring materials can be used if the power installed does not exceed 100W/m². When in doubt please consult the supplier of the flooring material.

It is not advisable to put an insulated carpet on floor heating, as this carpet has heating insulating qualities.

Velox heating cables are often installed in different kinds of sport venues, for example tennis- and squash halls.


How to choose the correct heating cable

To make it easier to choose the correct heating cable we have designed some of the most frequently used heating cables, i.e. standard lengths.

The standard lengths are made up with cold‐lead‐in cables and are delivered with "fixing strips" and caution labels.

How to choose standard length

Procedure:

‐ Measure the free floor area in m2

‐ Settle the surface power W/m2

‐ Choose the appropriate floor surface in the X‐axis of the chart.

‐ Follow the line up the intersectional point (break‐even) of the settled surface power.

‐ Necessary total power and suitable cable length can be read from the left of the diagram.

‐ Details about the standard lengths can be found in the table on page 14.

Example:

Floor surface: 14 m2

Surface power: 100 W/m2

Total power 1.4 kW

Correct length: 89 873 44 TCPR‐cable 89 871 96 TCPR‐concrete

Standard lengths


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How to calculate the resistance and the length of the heating cable when standard lengths cannot be used

When calculating the resistance and length of the cable this is the best way:

1. The power required (Pt) is estimated for the room.

2. The total resistance (Rt) for the cable is calculated.

3. The shortest cable length possible is estimated (l). 4. Cable type (Ω/m) is decided upon. 5. The correct length of the cable is determined (1). 6. The distance between the runs of the cable is

decided upon (c/c). 7. The solution. 8. Check calculation.

Example: Bathroom of 8 m2, Concrete floor with ceramic tiles

Power required according to chart: about 110W/m2.

1. Calculating the power required

Pt= W/m2 x floor surface

Example:

110 x 8 = 880 P

t = 880 W

2. Calculating the total resistance of the cable

U2

Ohms law for power R = ––––– P

Example: 2302 ÷ 880 = 52 R

t = 52 Ω

3. Calculating the length of the cable in meter

From the cable data sheet you get the information about the max. permitted power per m (P/m) for the cable type in question.

In concrete floors: TCPR 25 W/m In wooden floors: 15 W/m.

Pt

l = –––––––––– P/m

Example: 880 ÷ 25 l = 35 m

4. Calculating the resistance of the heating cable per meter

Example: 52 ÷ 35 R/m = 1.48 Ω/m The calculated value will (in theory) be 35m cable 1.48 Ω/m.

Controlling this in the cable data you will find that there is no cable with this resistance value.

Another cable with a higher or a lower resistance must be chosen. The nearest values are 1.9 resp. 1.3 Ω/m

You can not chose a cable with a higher resistance because the cable will then be too short and the resistance too high per meter cable.

The lower value is chosen (1.3).

5. Calculating the real length of the cable

Rt

l= ––– R/m

Example: 52 ÷ 1.3 l = 40 m

6. Calculating the c/c‐distance

The c/c‐distance is calculated as per this formula:

Floor surface x 100 c/c = _____________ l The c/c can be obtained in cm if the floor surface is in m² and the length in meter.

Example: 8 x 100 ÷ 40 c/c = 20 cm

It is often of advantage to apply the heating cable with varying c/c‐distances in a room. At the outer walls you apply them closer to each other and thus prevent a possible downdraft. With the same formula you have to make out an average to be used as initial value. Apply the cable with a shorter distance between the outer turns and enlarge correspondingly between the inner turns.

7. The solution

40 m cable (TCPR) 1.3 Ω/m is applied with a c/c of 20cm.

8. Check calculation

P= U²/ r(Ohm)/lpm x L(m)

Example: 2302 / 40 x 1,3 P = 884 W P/m2 = 111 W P/m = 21 W


Miscellaneous

In the example of calculation we have calculated with a supply voltage of 230V but it is also possible to design the cables for 380 V.

The length of the cables should not exceed 100m due to application and installation reasons. If the floor surface is large it is better to choose several short lengths instead of one long one.

Example: An office of 60m² is to be heated with floor heating

Power required 110 W/m2.

Total power: 6.600 W.

The best solution is that the power distributed symmetrically on a 3‐phase supply. 3 x 2.200W.

According to the previous method of calculation this is solved by three lengths, each 2.200 W and calculated for 230V supply voltage.

Result: 3 x 96 m TCP/R 0.25W/m

Control

Individual floor heating cables 230V are usually controlled by thermostats and sensors in the floor.

For bigger installations you have a control cabinet, equipped with all the necessary components, required for a safe and energy saving floor‐heating application.

VÄRMEKABELTEKNIK has a large‐scale programme on "standard‐cabinets" which meets the standard applications.

If required we also design and manufacture special control cabinets to the clients request.

Moore about control can be found in chapter "k" control


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Standard lengths velox tcpr 230 volt

Application in a bed of sand or in concrete

Part.no TCPR

Cable Current

Total resistance

90 W/m² 110 W/m²

Resistance W/m

Length m

Power W/m

PowerTotal (W)

A m Surf. Ohm

C/c mm

Surf. Ohm

C/cmm

8987182 40.00 7 23.5 175 0.8 300 2.0 265 1.5 2008987183 12.00 15 19.5 295 1.3 180 3.3 220 2.7 1808987184 8.00 17 23.0 390 1.7 136 4.5 255 3.5 205 8987185 5.35 20 25.0 495 2.2 107 5.5 275 4.5 2258987186 4.00 23 25.0 575 2.5 90 6.5 280 5.0 2258987187 2.90 2.7 25.0 675 2.9 78 7.5 277 6.0 226 8987188 1.90 35 23.0 795 3.5 67 9.0 250 7.0 2058987189 1.30 45 20.0 905 3.9 58 10.0 222 8.0 1828987190 1.00 53 19.0 1000 4.4 53 11.0 207 9.0 170 8987192 0.65 63 20.5 1290 5.6 41 14.5 230 11.5 1828987196 0.45 73 22.0 1610 7.0 33 18.0 246 14.5 1988987198 0.36 82 22.0 1790 7.8 29.5 20.0 244 16.0 195 8987202 0.25 100 19.4 2115 9.2 25 23.5 235 19.5 195

THE KIT CONTAINS: Heating cable according to the table with cold‐lead‐in cable mounted, caution labels.


Standard lengths floor heating

Velox TCPR 230 V thin floors

You can install our floor heating on top of all types of floors; gypsum board, particleboard or concrete floor in dry or wet rooms. An important condition is to keep the floor thickness down. Here every millimetre is important. A small level difference means that you do not have to raise sills and cut inward doors. By using our heating cables you will manage a level difference of approx. 15mm, including floor covering.

TCPR

A ready‐made heating cable element for floor heating when renovating and rebuilding; cable diameter 5‐6mm. The heating elements are of type return‐wire cable for connection in one end. Necessary total floor thickness min. 15‐20mm to ready floor surface.

Floor surf. (m²)

Cable type TCPR (W/m)

Cable length

(m)

Power Cable

(W/m)

Powertotal

(W)

Powerfloor sur.

(W/m²)

Powerconsump.

(A)

C/c

(mm)

Part.no

2.0 12.00 20 11 220 110 0.95 100 8987332

3.0 8.00 23 13 290 96 1.3 130 8987333

4.0 4.00 33 12 400 100 1.8 121 8987334

5.0 2.90 38 13 480 96 2.1 132 8987335

6.0 1.90 46 13 605 101 2.6 130 8987336

7.0 1.30 57 13 715 102 3.1 123 8987337

8.0 1.00 65 13 815 102 3.6 123 8987338

9.0 0.82 70 13 920 102 4.0 128 8987339

10.0 0.65 78 13 1045 104 4.5 128 8987340

12.0 0.45 95 13 1235 103 5.4 126 8987342

14.0 0.36 107 13 1375 98 6.0 131 8987344

16.0 0.25 130 13 1630 102 7.0 123 8987346

18.0 0.18 158 12 1860 103 8.0 120 8987348

20.0 0.18 150 13 1960 98 8.5 133 8987350

Control: Electronic thermostat Part.no. 12250 Velox E1 Floor heating thermostat, external mounting IP30 Part.no. 12251 Velox E2 Floor heating thermostat, flush mounting IP30.

The bulb is laid in VP‐pipe (10 and 16mm alt.) in the floor. The VP‐pipe must be mounted in the middle between two cable runs and 50‐100cm from the wall.

Thermostat set up: 24‐28°C.

Operating voltage: 230V.


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Protection against downdraft

In some (building) constructions thermal bridges can set in the bottom slab just where the slab meets the wall. This causes down draft. An efficient way to avoid this draft is to install heating cable in the bottom slab. The heating cable is applied in the concrete with one run around the bottom slab just inside where the wall meets the slab.

This type of heating cable installation is suitable to integrate into other types of heating cable installations, for example entrance, halls or bathrooms. Appropriate power: 20‐25 W/m cable. The cable is controlled manually or by a thermostat. The sensor is applied in a protective tube and is placed beneath the wall where the wall meets the bottom slab and 5‐10cm off the heating cable.

Other heating cable applications

Garages

Garage ways and drives can easily be kept dry by installing heating cable. With the specially designed Velox TCPRH cable you can apply the heating cable directly in the asphalt and thus obtain efficient and fast heating.

Stairs/entrances

Stairs, ramps and other entrances are also well suited to be heated with Velox heating cable.

There will be less rubbish and moisture on the premises. Protection against damp is another advantage with heated stairs and entrance areas.

Gutters and down pipes

Down pipes and gutters are other examples of applications where Velox heating cables can be used. For houses and garages the requirement is most often short lengths and therefore Velox Safe‐T is frequently the most suitable cable.


Telephone: +46‐301‐418 50 – Email: [email protected] – Homepage: www.vkts.se

Industrihuset Södra Hedensbyn 43

S‐430 64 HÄLLINGSJÖ S‐931 91 SKELLEFTEÅ

Sweden Sweden

Fax: +46‐301‐418 70 Fax: +46‐910‐881 33

Floor Heating

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