Electric underfloor heating: types and principle of operation, installation and recommendations

Recently, people are thinking about floor heating more and more often. This is dictated by both practical and aesthetic considerations: the absence of a radiator gives free rein to design imagination. There is a large selection of products for underfloor heating in stores, they all have different characteristics and can be designed for both the main and additional heat source. The most interesting here are electric underfloor heating, the use of which is virtually unlimited.

Thermal conditions in the room

Natural air circulation is observed in any room, be it an apartment or an office. Warm air rises and cold air sinks. During the heating season, when a radiator is hanging on the wall, the air flow is directed upward from the battery, then it

goes around the room on the ceiling, and already cooled air descends downward.

This situation is not comfortable. It turns out that it is cold on the floor, but there is nothing to breathe. Residents of the first floors feel this problem most acutely, especially in houses without a basement. In this case, the flow rate of the coolant can be increased, and the heating bills are large.

A warm floor can change this state of affairs. Breathing will be much easier, and your feet will be warm. This is especially important if there are children in the house who love to crawl on the floor. Carpets used to solve the problem of cold floors, but this source of dust and allergies is not suitable for everyone.

Types of warm floors

Today there is three ways of floor heating:

1. water;
2. electric;
3. combined.

In this case, the first one works from central or autonomous heating in the house, and the second and third - from electricity.

Pros and cons of water heating

An underfloor heating pipe is a very economical option. For this, both plastic and copper can be used, but even if the cost of the pipes is more expensive than the cable, you will save on costs. Say what you like, but the cost of a kilowatt-hour is now great. And if you have your own boiler room, then you will save on fuel: when heating the floor, there is no need to heat the coolant to high temperatures.

There are two disadvantages of such floors. So, for their installation in an apartment building, approval is required, because when you change the position of the heater, the flow rate of the coolant changes throughout the house.

But the main drawback is that such a system is not guaranteed to be secure. Pipes tend to burst, especially in central heating systems, where the seasonal start-up is accompanied by water hammer with an increase in temperature. But it's one thing when you have a radiator that is in plain sight, and a pipe hidden under the screed is quite another. You will not only have to open the floor, but also pay for repairs to the neighbors below. Thus, the water floor will be safe in a country house.

Electric floors

Electric floor heating is another matter. Here you are not limited either legally or economically. Of course, the calculation here has its own subtleties, which are often neglected. But if you get down to business wisely, you can make an electric floor as an additional source of heat, as well as the main one. How much it meets your expectations depends on several factors:

1. power consumption;
2. thermal conductivity of the flooring;
3. heat capacity;
4. efficiency of heat transfer to the interior of the room.

Often, disappointment comes not from the product itself, but due to its incorrect installation and the lack of ideas about what system to lay under what.

Features of heat transfer of a warm coating

The flooring in the house can be arranged in the form plank floor on logs and pie with screed. In the first case, wood serves as a good heat insulator, but a poor heat conductor. The need for floor heating in a house with wooden floors is rare: they are warm by themselves. Of course, you can lay both pipes and a cable under them, but then you will not heat the floor, but the space under it, the air. Boards from this can add a couple of degrees, but they will disappear when you just decide to set the thermostat to zero. Thus, the installation of an electric underfloor heating under wooden floors is impractical.

Another thing is a cement screed. It serves as a kind of heat accumulator. Its thickness is about 5 cm, the heat capacity is high, as is the thermal conductivity. Therefore, laying the underfloor heating system in it will be a very good solution.

Among floor coverings, tiles are the best conductors of heat, worse - linoleum and laminate. If we talk about the latter, then they have a limitation on operating temperatures: overheating is dangerous because the coating will begin to collapse and release harmful substances into the air.

Varieties of electrical surfaces

Attention should be paid to systems that are powered by the mains. There are several of them, and each can be described separately. Today there are the following types on sale:

1. resistive cable in a coil or in thermomats;
2. self-adjusting carbon rods in mats;
3. two-component film;
4. electrofluidic floors;
5. capillary systems.

Resistive cables

They consist of nichrome in isolation. Nichrome - high resistivity alloy. It is from it that the spiral in the electric stove is made.

Cables can consist of either one core or two. There is no fundamental difference between them, just a single-core cable will have to be pulled twice, and a two-core cable at the end is locked with a special sleeve. There is a slight difference in their internals. So, one core has polypropylene insulation, steel wire braid and outer insulation of flexible plastic, and in a two-core cable, each cable has its own insulation, between which a copper drainage vein. All of this is wrapped with aluminum-polyethylene tape and packed in flexible plastic.

High power cables are sold in coils, and small ones in mats, that is, they are fixed on a mesh and sold in rolls.

Rebar floors

They are also sold as mats, and carbon plays the role of a heating element in them. This material has one useful property - its power consumption depends on the ambient temperature. If the resistor always heats up, then carbon is where it is needed. Therefore, such mats can be laid all over the floor, there will be no overheating under the furniture.

Of the advantages of rod mats, two can be noted:

1. efficiency - they consume less electricity;
2. parallel connection of conductors; when one rod fails, the others will continue to work.

The disadvantages include a shorter service life.

Infrared films

The name is not entirely correct - all warm floors give off heat by radiation. Films differ from other types of floors in thickness, they can be laid directly under the covering. There are two types of them - carbon and bimetallic. The first ones are analogous to the rod ones with the only difference that the carbon in them is packed in a lavsan film.

The principle of operation of the latter is interesting in that in other cases people refuse such a natural phenomenon. It is about a combination of copper and aluminum. When it comes to wiring, everyone tries to connect copper and aluminum through terminals, since simple twisting leads to overheating. The fact is that these metals have different coefficients of thermal expansion, and when current passes between the conductors, gaps can appear, and this leads to even greater heating.

This property of metals was used only in the manufacture thermocouples for measuring devices and switches, and now copper and aluminum are enclosed in a polyurethane film, where they serve as a bimetallic heating element.

PEX pipe with cable

This system is a polyethylene pipe with a diameter of two centimeters. Antifreeze is poured into it and a heating cable wrapped in Teflon is laid. Thus, this floor is combined. It has many advantages, the most important of which is economical power consumption. Also, when the electricity is turned off in a house where there is no heating, the liquid in it does not freeze.

Such floors do not overheat, so they can be installed throughout the room without fear for the condition of the furniture and the covering underneath.

Compared to classic hot water heating, the pipe heats up evenly, so you can lay it in any way.

Capillary systems

This is a collection of thin tubes with distilled water, equipped with a heating element and a pump. The control unit of such a floor is the size of a book, but looks quite aesthetically pleasing. Compared to a classic water floor, the amount of liquid in it is small: a few liters. Such a tube is closed with a self-leveling coupler.

The main disadvantage of capillary floors is the limitation on the area that they can heat up. As a rule, it does not exceed 20 square meters. Another drawback is energy consumption: such systems have a power of about 2.5 kW, at the same time, the price for the set itself remains high too.

Installation of underfloor heating

Different types of electric floors are installed at different depths, and it depends both on the shape of the heater and on its power. The larger the heater, the better it should be recessed.

Resistive cable floors in coils are laid under a cement screed, at least 5 cm thick. The same goes for PEX pipes. In order for such a warm floor to warm you, and not your neighbor from below, you need to lay a roll-up insulation with a reflective coating under the screed, and lay a reinforcing mesh on it. A cable or pipe is attached to the mesh. To prevent them from floating up during the pouring of the floor, they should be fixed to the mesh with clamps.

Floors made in the form of mats can be covered with a thinner layer of leveler, and the films are laid directly under the covering. In the latter case, it is important that the surface on which the film is laid is flat: small bumps and pits can lead to tearing of the film and its failure.

Limitations and Recommendations

Underfloor heating installation is usually straightforward. You can do it yourself. But knowing some of the subtleties will not hurt you:

• Systems based on resistive cable, both in coils and in mats, cannot be installed where furniture or any stationary equipment will be located. Failure to follow this recommendation may result in overheating.
• The fixation of the heaters should not be done with gypsum mixtures. They do not conduct heat well and the cable underneath can overheat. If it is not possible to secure the mat with clamps, do it with cement mortars or tape.
• You should not give up the radiator if the system power is not enough for the main heating. Also, do not rely on even powerful cables when it comes to regions with severe frost and corner rooms.
• Tiles must not be laid on foil floors. They are designed for linoleum and laminate. If you wish, you can simply lay them under the carpet.
• It is better to use different cables in different rooms. Underfloor heating systems are equipped with a thermostat, and it will be easier to adjust the mode you want. This is especially important if you have different floor coverings.
• When buying laminate, always look at what temperature range you can use it.
• Remember to check the system during operation. Plug it in and measure the resistance. This way you can detect damage in time.
• If the power consumption of your floor is more than 2 kW, run a separate cable from the RCD to it. This applies to all wiring in the house. Do not overload its individual sections by hanging a bunch of consumers on one cable.
• The resistor cable must not be shortened or lengthened. This is a one-piece product, the performance of which depends on both the length and the cross-section of the cable. When lengthening, you will not get the maximum temperature, and by shortening the cable, you will simply burn it.

And, of course, if when buying a floor you were given a repair kit for it, do not lose it. After all, most of the malfunctions associated with electric floors are removable.