Building a floor heating - theory and practice

• The hot water heaters
  • Meandering installation
  • Bifilar / worm-shaped
  • Distances between the pipes
  • The Tichelmann principle
• Wet systems or drying systems
  • drying systems
  • wet systems
• Electric underfloor heating
• Häugig asked questions

Especially since the 1970s, underfloor heating has increasingly developed into a popular heating variant. Originally used as a supplement to the classic heating, it is now used in many new buildings as the sole heating. However, the construction of a floor heating system consists of numerous construction variants. We will show you which different types of construction are possible, how the heating system is installed in the floor and which laying methods exist.

The structure of the underfloor heating involves various points, such as the power supply, the insertion into the ground and the arrangement of the heating pipes. Only careful planning achieves effective operation. Keep in mind that energy is lost under furniture and that even heat distribution results in a pleasant living environment. Therefore, you must prepare a plan before you start laying. This concerns the arrangement of all elements of the heating. You have to decide how the inlet and outlet are to be realized and which valves are necessary. The pressure losses of the consumers and the heat exchangers as well as possible cold bridges on windows must be taken into account. Add to that the decision for the basic design:

water Leaders	electrical
- is laid in the ground - needs a lot of space	- flat construction - uncomplicated quick installation

The hot water heaters

One type of underfloor heating is the hot water heaters. It pipes are laid in the ground, which are flowed through by hot water. The overlying flooring heats up and the heat is released into the room. The pipes are made of plastic or copper, with the former being the most commonly used. Polyethylene is one of the most popular plastics. It is oxygen-tight, reducing the risk of corrosion in the boiler. In order to achieve the best possible utilization of the heat, the laying of the heating pipes is a crucial point.

• Installation Type:
  • meandering fashion
  • bifilar / helical

Meandering installation

The meandering type of laying leads to an uneven surface temperature in the room. There are areas that are therefore particularly hot, and areas that stay cooler. The procedure is mostly used for small rooms or in the edge area. The term "meander" comes from the area of ​​the rivers. He refers to a river loop in a sequence of several river loops. The meandering installation is based on the alternating arrangement of the pipes in parallel lines. In the area of ​​the flow, the heat output is the greatest. If the required heating demand in the room is small or if it is a small room, the unequal distribution of heat is compensated again or the heat losses that take place put the effects into perspective.

Double meander-installation:
The double meander laying is based on the meander laying. The heating pipes are laid as usual alternately in parallel rows. However, the laying distance has been doubled. The return is realized between the heating pipes.

Bifilar / worm-shaped

Bifilar means two-fold in the sense of "close together". The heating pipes are laid helically, starting at the outer edge. They are laid out in spiral circles to the middle of the room.

Tip: If supply and return pipes are placed side by side, a uniform heat distribution in the room is achieved. The opposing hot water flow directions prevent particularly hot or cool areas.

Distances between the pipes

The closer the pipes are laid side by side, the higher the thermal effect. In the past or older buildings it was recommended to vary the laying distance. Exterior walls and window areas cool down very quickly if there is insufficient insulation. Therefore, the distance was chosen smaller. While distances of at least 10 centimeters were realized in the rest of the room, the pipe spacing at cooler places fell below this limit. Modern buildings require no variation of the distance in this point. Since good external insulation and window insulation are now used, no extremely strong cooling surfaces.

The Tichelmann principle

The basic principle is based on the same pipeline length for the refrigeration and heat transfer medium. When setting up, look at the supply and return lines together. The mass flow is divided evenly, since at each delivery point consistent pressure losses occur. The advantages are in the simple construction. The supply and return lines are arranged in the same shape. The hydraulic adjustment is easily realized. The advantages also include the high level of operational safety, as there is no additional control or moving parts. The disadvantage is the greater amount of piping. Calculate therefore before the election the exact costs. Another shortcoming is the lack of expansion options. Since it is an exact vote of the transfer, changes to the principle can no longer be carried out. So that you can implement the Tichelmann circuit, all consumers and heat exchangers must produce the same pressure loss. In any case, the objects considered include:

• radiator
• solar collectors
• air heaters
• Storage
• Wall heating register

In the case of unequal pressure losses, no complete adjustment is achieved. You have to realize an additional hydraulic adjustment . The equalization of the pressure losses on the heating surfaces must be guaranteed.

Wet systems or drying systems

The underfloor heating can be laid in wet systems and in dry systems. In the wet system, the pipes are laid in anhydrite screed or cement screed. Drying systems are realized by means of dry screed plates.

drying systems

The pipes are laid in the insulating layer underneath the floor covering. They are attached to the carrier insulation. Thanks to Wärmeleitblechen the heat distribution is optimized. In the case of dry systems, you can also apply the topsoil directly. You have the choice of different types of flooring, such as laminate, parquet or tiles. The advantages are the faster heating up and the lower flow temperature. This variant is particularly well suited for the modernization of buildings and for old buildings.

Dry screed panels can be provided with a special milling in which the heating pipes are attached. You benefit from the simplified way of working and the time savings. If you have little experience in laying underfloor heating, this version is particularly well suited.

wet systems

Wet systems bear their name because the pipes are enclosed by the initially wet screed. The fixation takes place in different ways. So you can fasten the pipes on steel support mats by means of clamps. Or you bring out a plastic stud plate and fix the pipes there.

Electric underfloor heating

The underfloor heating systems can be laid in the form of hotplates. They are connected to the mains and do not require the complicated laying of piping systems. Heating foils are designed and are particularly easy to use. They can be applied in the screed as well as on the screed. The advantages are therefore not only in the reduced effort but also in the low height. You can install heating cables in the adhesive bed of the tiles and thus save considerable height. Films can also be laid under the laminate.

Tip: Special care is required in wet areas. The humidity must not lead to defects or electric shocks. Therefore, special products for wet rooms are offered, which should be used in any case.

The basic construction of electric underfloor heating

• Heating mats and heating foils are already ready for installation
• Mats can be self-adhesive
• Recommended maximum length of the heating mat: 20 meters
• up to 1 meter wide
• Construction of the individual mats: heating cable with support mats
• Lay heating cables evenly on support mats
• Laying is possible under different floors: stone floors, parquet, laminate and much more
• in the case of parquet: not more than 150 watts of power per m²
• Lay electric underfloor heating on the impact sound insulation

Further information in our article Electrical underfloor heating installation

Häugig asked questions

What is the cost of underfloor heating ">

Length: 5 meters
Width: 7 meters
Area: 5 mx 7 m = 35 m²
Price for heating per m²: 40 euros

Total price for underfloor heating: 40 Euro x 35 = 1, 400 Euro

Can I make the installation myself?
You can install the underfloor heating yourself, only for the connection to the water supply and the drain should be consulted a specialist. The pipes can be easily introduced into the ground after setting up a plan. Much less expensive is the laying of heating mats. If necessary, they can be cut to size in accordance with the manufacturer's instructions.

Tip: Therefore plan the renovation of the floor covering and the installation of the underfloor heating in combination.

Further Link: The advantages and disadvantages of underfloor heating

Tips for quick readers:

• Dry laying or wet laying
• Meandered: Uneven surface temperature
• Modular installation: even temperature distribution
• Helical installation: Tubes spiral towards the center of the room
• little dust upset
• disturbing radiators are avoided
• Living environment is pleasant
• Heating pipes can be laid in the screed
• Dry screed panels may have devices for heating pipes