Electric underfloor heating: varieties and principle of operation, installation and recommendations
Varieties of electric underfloor heating and their characteristics
More and more people have been thinking about underfloor heating lately. This is dictated by both practical and aesthetic considerations: the absence of a radiator gives free rein to design imagination. The stores offer a wide range of floor heating products, all of which have different characteristics and can be designed for both the main and additional heat sources. The most interesting here are electric underfloor heating, the use of which is virtually unlimited.
- Thermal regime in the room
- Types of warm floors
- Pros and cons of water heating
- Electric floors
- Features of heat transfer of a warm coating
- Varieties of electrical surfaces
- Resistive cables
- Rod floors
- infrared films
- PEX pipe with cable
- Capillary systems
- Installation of warm floors
- Limitations and recommendations
Thermal regime in the room
In any room, whether it is an apartment or an office, there is natural air circulation. Warm air rises and cold air sinks. During the heating season, when a radiator is hanging on the wall, the air flow is directed upwards from the battery, then it wraps around the room on the ceilingand cooled air descends.
This situation is not comfortable. It turns out that it is cold on the floor, but there is nothing to breathe. This problem is most acutely felt by residents of the first floors, especially in houses without a basement. At the same time, the flow rate of the coolant can be increased, and the heating bills can be large.
Underfloor heating 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. Previously, carpets solved 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 underfloor heating:
At the same time, the first one is powered by central or autonomous heating in the house, and the second and third ones are powered by electricity.
Pros and cons of water heating
An underfloor heating pipe is a very economical option. Both plastic and copper can be used for this, but even if the cost of pipes is more expensive than cable, you will save on costs. Say what you like, but the cost of a kilowatt-hour is now high. 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, coordination is required, because when you change the position of the heater, the coolant flow throughout the house changes.
But the main disadvantage is that such a system is not guaranteed to be secure. Pipes tend to burst, especially in central heating systems, where its seasonal launch 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 quite another is a pipe hidden under the screed. 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 underfloor heating is another matter. Here you are not limited either legally or economically. Of course, there are subtleties in the calculation here, which are often neglected. But if you approach the matter wisely, you can make the electric floor both an additional source of heat and the main one. Whether it will meet your expectations depends on several factors:
- power consumption;
- thermal conductivity of the floor covering;
- heat capacity;
- efficiency of heat transfer to the interior.
Often, disappointment does not come from the product itself, but due to its improper installation and lack of ideas about what to lay under which system.
Features of heat transfer of a warm coating
Flooring in the house can be arranged in the form plank floor on logs and a pie with a screed. In the first case, the tree serves as a good heat insulator, but a poor conductor of heat. The need for floor heating in a house with wooden floors rarely arises: they are warm in themselves. Of course, you can lay pipes and cables under them, but then you will not heat the floor, but the space under it, the air. The boards may add a couple of degrees from this, but they will disappear when you simply decide to set the thermostat to zero. Thus, the installation of an electric warm floor 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, tile is the best conductor 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 break down 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 The following types are on sale:
- resistive cable in a coil or in thermomats;
- self-adjusting carbon rods in mats;
- film two-component;
- electrofluid floors;
- capillary systems.
They consist of nichrome insulated. 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 the two-core cable at the end is locked with a special sleeve. There is a slight difference in their internal structure. So, one core has polypropylene insulation, a steel wire braid and an outer insulation made of flexible plastic, and in a two-core cable, each cable has its own insulation, between which a copper drainage core is laid. All of this is wrapped with aluminum-polyethylene tape and packaged in flexible plastic.
High power cables are sold in coils, and low power cables are sold in mats, that is, they are fixed on a grid and sold in rolls.
They are also sold in the form of 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 will always heat 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:
- efficiency — they consume less electricity;
- parallel connection of conductors; when one rod fails, the others will continue to work.
The disadvantages include a shorter service life.
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 coating. There are two types of them — carbon and bimetallic. The first ones are an analogue of 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 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 a different coefficient of thermal expansion, and when current passes between the conductors, gaps may occur, 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, such a floor is combined. It has many advantages, of which the most important is the economical consumption of electricity. 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 mounted throughout the room without fear for the condition of the furniture and the coating under it.
Compared to classical water heating, pipe heats up evenlyso you can lay it in any way.
This is a set of thin tubes with distilled water, equipped with a heating element and a pump. The control unit of this floor is the size of a book, but it 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 screed.
The main disadvantage of capillary floors is the limitation on the area that they can warm 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, while the price of the kit itself is also high.
Installation of warm floors
Different types of electric floors are mounted 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 applies to PEKS pipes. In order for such a warm floor to warm you, and not a neighbor from below, you need to lay a rolled insulation with a reflective coating under the screed, and lay a reinforcing mesh on it. A cable or pipe is attached to the grid. To prevent them from popping up during the pouring of the floor, they should be fixed to the grid with clamps.
Floors made in the form of mats can be covered with a thinner layer of leveling, and the films are laid directly under the coating. In the latter case, it is important that the surface on which the film is laid is even: small bumps and pits can lead to tearing of the film and its failure.
Limitations and recommendations
Installing underfloor heating is usually not difficult. This can be done by hand. But knowing some subtleties will not hurt you:
- Systems based on resistive cable, both in coils and in mats, cannot be carried out where furniture or any stationary equipment will stand. Failure to follow this recommendation may result in overheating.
- Heaters should not be fixed with gypsum mixtures. They do not conduct heat well, and the cable under them can overheat. If it is not possible to fix the mat with clamps, do it with cement mortar or tape.
- Do not abandon the radiator if the system power is not enough for the main heating. Also, you should not even rely on powerful cables when it comes to regions with severe frosts and corner rooms.
- Tiles cannot be laid on film floors. They are designed for linoleum and laminate. If desired, they can be laid simply under the carpet.
- It is better to use different cables in different rooms. Underfloor heating systems are equipped with a thermostat, and the mode you need will be easier to adjust. This is especially important if you have different floor coverings.
- When buying a laminate, always look at the temperature range in which it can be operated.
- During operation, do not forget to check the system. Plug it in and measure the resistance. So 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. You should not overload its individual sections by hanging a bunch of consumers on one cable.
- The resistance cable must not be shortened or extended. This is a one-piece product, the operation 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 you were given a repair kit for your floor when you bought it, don’t lose it. After all, most of the problems associated with electric floors are fixable.