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Floor heating guide


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Floor heating in general

History

Floor heating is not a new invention. In the Roman empire, 2000 years ago, the Romans invented a floor heating system. This system used the hot gasses from the chimney. The gasses were led through channels in the floor and thereby heating up the floor.

 

Basic

Floor heating becomes more and more popular and becomes a must in new houses. All types of floorings is suitable for floor heating. Tiled floors and stone floors  becomes very comfortable with floor heating. Wooden floors have in recent years become popular, however there is some simple rules to follow to  accomplish a long lasting wooden flooring.

There are two types of  floor heating:

  • Comfort floor heating

  • Primary Floor heating

Comfort floor heating is used in rooms with other heating sources such as radiators or furnace. With the comfort heating you can achieve the advantages of a nice warm floor.

Primary floor heating is for rooms as the only heating source.

 

Basic function of floor heating 

The human body feel most comfortable by having 18-20°C at eye height  and 22-24°C at the feets. If you feel cold at your feets, the hole body feels cold.

The use of a floor as a heating source have several advantages. The floor surface gives a uniform heating in the room. Most of the heating (80%) is heat radiation and approximately 20% is accomplished by heating up the air. With the floor surface as heating source, the floor temperature is only a few degrees higher than the desired room temperature. In well insulated rooms a floor temperature of 23°C gives a room temperature of 20°C.

Floor heating is a low temperature system that gives the best comfort. Radiators  is a high temperature system witch gives high temperatures at the roof and a high air circulation

The nature of floor heating gives the opportunity to save energy since the temperature in the room can be kept 1-2 °C lower compared to systems using radiators.

Other advantages are

  • Low temperature heating = energy saving
  • Better comfort
  • No space occupied by heating devices
  • Rooms easier to furnish
  • Less dust in rooms
  • Low installation cost
  • No maintenance

 

Heating capacity

The heating power in the floor  must have a heating capacity able to warm up the room in the coldest winters.  The thermostat controls the energy in the floor. This is always advisable.

Below you will find the recommended power (W/square meter) for a house insulated according to today  standards in Scandinavia.

For houses insulated acording to previus standards it is advisable to contact us for calculation of power.

Recomended heating capacity for primary heating

Room Heating capacity, W/m ²
Hall, entré 60 -150                 Note 1
Living room, Sleeping room, kitchen 60 -100
Bath room, Shower 120 -150               Note 2
Concrete floors with excellent insulation 50 - 80
Concrete floors with bad insulation 120 - 150
Garage 60 - 120

Recomended heating capacity for Comfort heating

Room Heating capacity, W/m ²
Hall 60 - 80                 Note 1
Living room, Sleeping room, kitchen 50 - 70
Bathroom, toilet room 60 - 100               Note 2
Concrete floors with excellent insulation 40 - 60
Concrete floors with bad insulation 60 - 100
Garage 60- 80

 

Note 1: The higher heating capacity is recomended to dry floor and wet footware
Note 2:
The higher heating capacity is recommended when floor space is substantial reduced by toilet, drains, bath etc.

Since energy loss in low energy houses is very low,
comfort heat will be a sufficient heating source 

 

Choice of heating cable or heating mat

The choice of heating cable or heating mat depends very much of the floor and skill. In general we recomment according to the following.  

Heating cable  
DVCM-10  

Heating cable
DVCU-17

Heating mat
DVCM-120  /  DVCM-150
  • Floors with one or more cold walls
  • Rooms with many odd shapes
  • Floors with parquet
  • Floors with laminate
  • Casting concrete floors
  • Regular square rooms

Choice of thermostat

The thermostat serves several purposes. First of all it shall maintain a comfortable room temperature and reduce energy cost. The DVTH-131 and DVTH-132 series offer both.

In most cases we recommend a thermostat with both floor sensor and room temperature sensor. Wooden floors always need a thermostat with floor sensor. Wood is a material witch contains a certain percentage of water. To avoid drying out the water of the wood, the floor sensor will ensure the surface of the wooden floor never exceed 28 °C.

Floor sensor thermostat is recommended for comfort heating 

Quality thermostats is characterised by having a very precise temperature maintainance. This ensure best comfort and energy saving.

When the thermostat orders the heating system to start, the centre of the room warms up faster than the area where the thermostat is installed. This is due to the fact that the centre of the room is usually closer to the heating source than the thermostat. It is also easier to heat since the inertia in this area is very weak.

The thermostat case and the wall on witch it is installed represent an important mass and it takes longer to heat and to cool them than the air in the centre of the room. The temperature reading at the thermostat is therefore out of phase with the real temperature at the centre of the room.

Therefore a 1 °C dead band at the thermostat may result in a variation of 4 °C in the centre of the room

Both our thermostats series DVTH-131 and DVTH-132 is the most advanced thermostats on the market and is equipped with an intelligent anticipation algorithm, witch accelerates the thermostats response and reduces the gap between the temperature read by the thermostat and that at the centre of the room.

 

Floor constructions

Tiles on concrete in dry rooms:
Electrical floor heating is  excellent under tiled floors. All kinds of tiles, stones, marble and slates is well suited. Without floor heating they  feels a little chilly. 
1. Make sure the surface is smooth and levelled  
2. Clean surface with vacuum cleaner  
3. Apply primer to secure good adherence for next layer (nothing can adhere on dust)  
4. Install heating cable or heating mat  
5. Before covering the cable/mat let an certified electrician control the cable.  
6. Apply tile adhesive and tiles.
7. Let the certified electrician connect heating cable and thermostat  

Tiles on concrete in wet rooms:
1. Make sure the surface is smooth and levelled  
2. Clean surface with vacuum cleaner  
3. If it is a new floor without a sealeant, then apply sealant according to national standards.
4. Apply primer to secure good adherence for next layer (nothing can adhere on dust)  
5. Install heating cable or heating mat  
6. Before covering the cable/mat let an certified electrician control the cable.  
7. Apply tile adhesive and tiles.
8. Let the certified electrician connect heating cable and thermostat  

Tiles on chipboard in dry rooms:
1. Make sure the surface is smooth and levelled  
2.  Make sure the under floor is sufficient rigid. If not it must be enforced by either floor gypsum boards or levelling compound.
3. Clean surface with vacuum cleaner
4. Apply primer to secure good adherence for next layer (nothing can adhere on dust)
5. Install heating cable or heating mat
6. Before covering the cable/mat let an certified electrician control the cable.
7. Apply tile adhesive and tiles.
8.  Let the certified electrician connect heating cable and thermostat

Parquet – wooden floors or vinyl floors on concrete in dry rooms:  
1. Make sure the surface is smooth and levelled  
2. Clean surface with vacuum cleaner  
3. Apply primer to secure good adherence for next layer (nothing can adhere on dust)
4. Install heating cable or heating mat
5. Before covering the cable/mat let an certified electrician control the cable
6. Apply levelling compound
7. Parquet –wooden floors:
Vinyl floors: 		Apply damper felt.
Apply glue and vinyl
8. Let the certified electrician connect heating cable and thermostat

 

Important:
Tile adhesive normal needs 28 days to harden without heating. You must not switch on the heat in that period. The water in the tile adhesive is a part of a chemical process that ensures the tile adhesive becomes strong. Always follow the instructions from the manufacturer.