The device of the electric floor and its types, the principle of operation, the choice of design, the calculation of the heating element and the rules for its laying. An electric floor is a space heating system that consists of thermocouples and is installed under the floor covering. It can serve as both the main and additional heat source. Heating cables, mats and films are used as working elements, the installation of which is not particularly difficult. You will learn how to make an electric underfloor heating yourself from our material.
How the electric floor works
The electric floor system is fundamentally different from the usual water radiators in terms of room heating. Central heating is based on the convention of air, which, when heated by batteries, rushes upward, and after partial cooling at the ceiling, returns to the floor to re-set the temperature from the appliances. For this reason, the air near the floor is always slightly cooler than near the ceiling surface.
During the operation of a warm electric floor, the highest temperature is concentrated in the lower part of the room, decreasing as it approaches the upper floor. Such a distribution of air masses creates an enhanced feeling of comfort, since the legs are always warm, and the head is a little cooler, which is in full accordance with the well-known Russian proverb.
Convection flows in this case are absent. In addition, due to the larger heating surface area of the electric floor, the heat transfer of its system is much higher than that of heating radiators.
Many skeptics argue about the allegedly harmful effects of the magnetic field of such a room heating system on a person. However, against this opinion, there is a sufficient number of strong arguments in favor of an electric floor:
- The magnetic induction of an electric floor does not exceed 2-3 microns T, which is much lower than the permissible value. And the radiation of the infrared film floor is only 5-20 microns and corresponds to a similar parameter of the human body, without causing any harm to it and, on the contrary, improving blood circulation by rapidly warming it.
- Cleaning of dust in a room with a warm floor can be done much less frequently than with radiator heating, the convection of which contributes to its accumulation on furniture and household items.
- The temperature of a room heated by a warm electric floor is easy to regulate by choosing its optimal mode. This saves the coolant. In addition, such a system can be turned off altogether during the absence of residents in an apartment or house.
- When choosing an electric floor as the main coolant, it is possible to remove unattractive water radiators from the walls. This is true for regions with moderate winter temperatures.
The main types of electric floor
Electric floors are divided into three main types according to the design of the heating element: cable, film and rod.
Cable electric floors
If the main task of a conventional electric cable is to transfer energy over a distance, while not particularly heating up, then the purpose of the cable in the floor is somewhat different - the complete conversion of electricity into heat. The sheath and insulation of the heating cable can withstand temperatures up to 70 degrees.
There are two types of such products. One of them is resistive cables, their resistance index is constant. Another type is self-regulating cables, the heating of which can change depending on temperature fluctuations in the air. This means that near doors and windows such a cable will warm up more, and less under furniture in the room.
In addition, the cable can have one or two cores. They are insulated with rubber, reinforced with fiberglass and covered with an aluminum screen. Electric floors presuppose installation of cables in sections, elastic mats or pipes with an anti-freeze liquid.
Heating sections of the cable floor are indispensable for complex room layouts, as they are able to repeat any turns and bends. In addition, they are suitable for any floor covering, from linoleum to artificial stone.
The sectional cable floor should be installed before the concrete screed is laid. In low rooms, an increase in the level of the finished floor should be taken into account. But in the case of removing the old wooden flooring, the height of the log will be quite enough for the installation of an electric sectional heating system, and the height of the ceiling may even increase slightly.
Electric floor heating mats are made of fiberglass mesh on which the cable is already laid. This allows the installation of heating elements on top of the concrete screed, and not under it, as in the previous case. The mats have a self-adhesive base, so their installation is as simple as possible. In this case, the floor level rises by only 3 mm.
In a liquid floor, the cable is laid in an anti-freeze solution, so it rarely burns out. Its energy consumption is very economical, and the repair is simple: the damaged area can be easily replaced using couplings for a new connection.
Film electric floors
The electric film floor has a more complex structure. Its design consists of flat-shaped heating elements, which are placed between layers of a very strong and thin heat-conducting film, which is subsequently sealed hermetically.
There are two types of such floors: bimetallic and carbon. The construction of a bimetallic underfloor heating consists of a polyurethane film and conductors of copper and aluminum alloys laid in it. The floor is produced in rolls, the canvases of which are divided into square sections, any of which can be cut as needed. The bimetallic film cannot be mounted under the tiles.
Here you can use linoleum, laminate or carpet as an outer covering. Having excellent thermal conductivity, the film quickly heats up the room, however, in conditions of high humidity, its use is not recommended, that is, such a floor is not suitable for a kitchen or bathroom.
A carbon electric floor consists of two soldered layers of mylar film, between which there are conductors made of an alloy of silver and copper, as well as strips of graphite. Such heaters can be installed not only on the floor, but also on ceilings or walls. The main advantage of such systems is their small thickness up to 0.5 mm. Their installation is very fast.
It is believed that of all types of electric underfloor heating, it is the carbon heating film that has the most beneficial effect on human health, identical to sunlight. This property is possessed by its infrared radiation.
Rod electric floors
They are flexible mats equipped with heating elements - infrared carbon rods with high heat transfer. These space heating systems combine the advantages of cable and foil floors.
The main advantage of the film system with core mats is a high degree of reliability. The parallel connection of carbon rods in the system allows it to work even if several heating elements are damaged.
From the cable system, the rod infrared floor has inherited the possibility of uncomplicated installation in tile adhesive or floor screed. Due to its self-adjusting property, the carbon mat is almost 60% more economical than the cable mat. He is not afraid of local overheating, so such a floor can be placed under furniture.
The service life of core floors is designed for 50 years, the warranty period of operation is 20 years. The main manufacturers of such systems are specialized companies in Europe and South Korea.
Features of choosing an electric floor
If done correctly, the space heating system will function as efficiently as possible with the lowest possible cost of electrical energy. Before choosing an electric floor, it is necessary to determine the required degree of heating of the room, the type of floor covering and installation method, as well as the floor area allocated for laying heating mats or foils.
Room heating degree
An electric floor can be used as the only main heat source in a room, or it can comfortably heat the floor covering. Therefore, the first step to ensure the optimal temperature in the room with the help of heating elements is to determine the required degree of heating: will there be enough additional heating of the floor surface or will it be necessary to compensate for the lack of centralized heating by installing an electrical heating system.
The solution to this question will be to determine the optimal power that is required in this case. For comfortable floor heating, 100-150 W / m will be enough2, for the main heating system - 160-200 W / m2, for unheated rooms such as loggias and balconies - 200-250 W / m2.
Coating types
Each floor covering has an individual thermal conductivity. It must be compatible with the optimum electrical heating output. Coating manufacturers usually indicate in the product documentation the temperature limit for its operation.
For example, for linoleum with an optimal floor heating power of 100-130 W / m2 the surface temperature of the finish should be 26-28 ° C. Therefore, such a coating is recommended to be used in conjunction with an electric floor only for additional heating of the room. For linoleum and laminated coverings, in most cases, CALEO infrared film, DEVIDRY heating mats from DEVI and TVK-130 LP from THERMO are used.
Ceramic granite and tiles can be used for any type of electric heating, since their thermal conductivity indicators are compatible with sufficiently high powers of heating elements - 150-220 W / m2… Heating mats from the companies THERMO, AEG, IQWATT and DEVI are used as a warm floor for such coatings.
Mounting method
When choosing an electric floor, one should take into account the type of formation of the surface on which the room heating system will be located.
For overhaul repairs, Deviflex 18T (Denmark), HC 800 from AEG (Germany) or SVK-20 heating cable from THERMO (Sweden) are recommended for laying an electric floor under a cement screed with a thickness of 30-50 mm. These electric floors are compatible with any topcoat. The heating system can be turned on after the screed has polymerized, that is, after a month.
If the screed is already ready, heating mats or rod infrared floors are suitable for electric heating. Heating mats are installed in a 10-15 mm leveling screed layer, and the core floor is mounted under tile adhesive.
For the finished screed, there is also a dry method for installing an electric floor, which allows you to leave the height of the room unchanged. In this case, CALEO infrared film is used. This heater turns on immediately after installation.
For any of the options for installing an electric floor in a room, you should pay attention to its proximity to a cold foundation or the presence of heated rooms above and below. This is necessary, since in the case of large heat losses, a heat insulator will have to be laid under the heating elements - mineral wool, foam, etc.
Footprint
Almost all electric floors are installed in an area free from heavy furniture and household appliances. This is extremely important so that the heating system is not locked in a confined space, for example, under a cabinet, as in such cases it could overheat and fail.
If there is any doubt that the furniture will always be located in a certain place, the choice of an electric floor should be stopped on a rod model with a self-regulating function, for example, a UNIMAT heating mat. This function provides the system with the ability to self-adapt to the environment by increasing or decreasing its power level if necessary. This results in significant energy savings.
Electric floor calculation rules
It is performed to determine the number of heating mats, infrared film and cable power. It is not difficult to determine the required area of the electric floor kit. To do this, subtract the area occupied by furniture from the total area of the room. For example, if the area of the room is 12 m2, and of them are occupied by furniture 5 m2, then it will take 7 m to heat it2 electric floor (12-5 = 7).
Heating mats must not be lengthened or shortened, therefore, if they are used, the required area of the underfloor heating should be rounded down to a lower value. You can cut the infrared film. This allows you to disconnect and connect individual parts of the electric floor, as well as combine its various sets during installation. For example, at 9 m2 the floor can be installed in sections of 4 and 5 m2 or 2, 3 and 4 m2… In addition, one set of electric heater can be distributed over several rooms.
The power of the heating cable is determined by the product of two values - the nominal heating power and the value of the free area of the room. The first value provides for:
- comfortable heating of the coating 150-200 W / m2;
- main room heating 160-200 W / m2:
- heating of cold rooms 200-250 W / m2.
The second value is the difference between the total area of the room and the area occupied by furniture. Let's consider the calculation using an example. For heating a kitchen area of 10 m22, of which 4 m2 occupied by furniture, a rated power of 160 watts is required. In this case, the required power of the heating cable will be: 160x (10-4) = 960 W. We round it up to the nearest standard value of 1020 W.
After that, it becomes clear that the SVK-20 cable is suitable for heating this kitchen if the THERMO model is used. Further installation of the electric floor should be carried out taking into account the step of laying the cable and the area of the room.
Electric underfloor heating installation technology
The process of installing an electric floor consists of the preparatory and main stages. Preparation should begin with design. It is carried out in this order:
- It is necessary to draw up a diagram of the room, which will indicate the location of the furniture tightly installed on the floor surface. Then you need to select an indent of 5-10 cm from the wall, taking into account the position of the skirting boards. The remaining area of the room can be used for the installation of a warm floor.
- Next, you should make sure that the power of 1 m2 section of the heater to the standard value, measure the electrical resistance of the cable and compare it with the value indicated in the product passport. The error should not exceed 10%.
- It is necessary to determine the place on the wall to install the thermostat. Here you will need a junction box and a 25x30 mm strobe for a 220 V power wire going down from the device. In this case, it is imperative to provide grounding.
To go through the main stage of installing an electric underfloor heating with your own hands, you should perform the following steps:
- Clean the concrete floor screed and prime it with a primer. It will strengthen the surface and get rid of dust.
- Using the building level, it is necessary to determine the magnitude of the floor differences in height. If their values are more than 10 mm, it will be necessary to paste over the base surface with polystyrene so that its upper plane is even and horizontal over the entire floor area allotted for heating.
- A plaster metal mesh should be fixed over the thermal insulation. Its fixation can be done simultaneously with the fastening of the insulation with long dowels and washers. If the insulation is glued to the base, the plaster mesh can be fixed directly to the insulation with plastic clips.
- The heating cable should be laid with a snake on the mounting grid and fixed to it with plastic ties.
- A corrugated sleeve with a diameter of 16 mm must be laid in the groove that runs from the installation box to the warm floor, avoiding its sharp bends.
- A temperature sensor must be inserted into the sleeve so that later, if necessary, it can be easily replaced with a new one. Place the end of the tube with the sensor as close as possible to the floor for accurate readings.
- Seal the strobe with cement or plaster mortar.
- Measure the resistance of the cable again and enter the measurement data in the warranty card.
- Make a scheme for laying the heating cable with marks for the location of couplings and end couplings, temperature sensor, indents from walls, etc.
- For a preliminary check of the electric underfloor heating system, a thermostat must be connected. After its completion, the device must be turned off and installed again after finishing the finishing work.
- Perform a cement-sand screed. After four weeks, it will gain full strength. Before this time, it is not recommended to make test connections of the electric floor. A floor test can be done by measuring the resistance of its cable.
- Place the floor covering on the screed.
The formula will help to calculate the step of laying the heating cable: W = 100XPO / DK. Here W is the laying step in cm, PO is the area of the electric floor, DK is the cable length in cm. Watch the video about the installation of the electric floor:
In general, there is nothing particularly difficult in laying electric floors. They are much easier to install than hot water heating systems. The main thing in this business is hard work and a little theory from this article, thanks to them your warm floors will be able to warm and delight friends and loved ones.
