Heated floors in one form or another are present in almost every modern renovation. But there are several types of heating systems, each has its own characteristics and limitations for use, so in our review we will compare different types of underfloor heating, compare the pros and cons.
Types of underfloor heating
To begin with, it is important to come to an agreement in terms and definitions. Underfloor heating is a common name, it means a certain layer under the floor covering, which contains heating elements, and from below is protected from other building structures by a layer of heat-insulating material. It is by the type and principle of operation of the heating elements that water, electric cable and electric film heating systems are distinguished.
A water heated floor is an integral part of a liquid heating system along with radiators, a heating unit and forced circulation devices. The heating element in them is a coil made of a thin pipe, laid over the entire plane of the heated area. The problem with a water floor is that heating is carried out only along the pipe laying line, so they are hidden under a fairly thick layer of cement screed. Due to this, the temperature is distributed evenly and the effect of the so-called thermal zebra is eliminated. Water floor heating is a technically very complex system, because the operating temperature of the coolant in the circuit should not exceed 30-32 ° C, which requires the installation of a special thermostatic unit. It is also worth noting that without forced circulation, a warm water floor cannot work, and the maximum length of the pipe in the loop is 100-130 m.
A cable underfloor heating device is similar to a water floor, but instead of tubes with a heat carrier, a cable with high resistivity is used. In installation, such a heating system is simpler, but it is necessary to pre-calculate the length and resistance of the cable in each heating section in order to provide the necessary heating power. The main disadvantage of electric heating with a cable is its low service life - 15-20 years versus 50 for a water-heated floor. Of the other disadvantages, the most pronounced requirement for high power electrical connection, the need to ensure electrical safety in the form of grounding and differential protection, as well as relatively high heating costs. From a technical point of view, single-core and two-core heating cables are distinguished, which have no other differences, except for the connection and installation scheme.
Film underfloor heating is sometimes called infrared, which is not entirely correct, because any of the heating systems described above is capable of radiating heat. This misconception arises because the heating film, and this is indeed the most common resistive type heating element, does not transfer heat directly to the screed, as does a cable or pipe with a coolant. The film is not walled up in the screed, but is placed under the coating, while there is always a minimum air gap between them, which is why heat transfer is carried out mainly by infrared radiation. Advantages of the film: ease of installation and uniformity of heating, disadvantages - limited specific power, low service life comparable to the floor covering itself, as well as the impossibility of arranging such heating under materials that require fastening to the base: parquet, ceramic tiles or porcelain stoneware. In addition, we note that there are films with carbon and bimetallic heating elements, although there is no fundamental difference between them.
Application conditions
Each type of underfloor heating must first be considered from the point of view of the admissibility of its use in certain conditions, dictated by the design features of the building, fire and electrical safety requirements, as well as the operating rules of the floor coverings used.
The water heated floor in this regard has the greatest number of restrictions on its use. For example, it cannot be connected to the municipal heating system, and it is also prohibited to install water floor heating on floors under which residential premises are located. Liquid underfloor heating is the only type of underfloor heating system that is absolutely safe for use in wet areas. However, when laying pipes, a thickness of the covering part of the screed of at least 40 mm is required both to distribute heat and to protect the coil, which is extremely vulnerable to mechanical damage.
Both types of electric underfloor heating are most advantageously used in facilities that do not have their own liquid heating system or are connected to a central heating supply. The advantage of a heating cable over a water-heated floor is the ability to ensure a more dense laying of heating elements without additional effort, which is impossible in the case of a tubular coil due to a limited minimum bending radius. Nevertheless, a screed device is still required, although the covering layer can be reduced to 20-25 mm.
An example of the layout of the underfloor heating film in the room
One of the disadvantages of heating with an electric cable is similar to liquid systems: the placement of heating zones on the floor is determined once during installation, which limits further redevelopment and rearrangement of the premises. It is believed that the presence of heating under the furniture does not have a negative impact on it due to relatively low operating temperatures, but this definitely does not add durability to the system itself. In addition, the heated area on which the furniture is installed is automatically excluded from the heating system. The film floor is devoid of this drawback: the placement of the heating elements is quite easy to change by temporarily dismantling the floor covering.
Purpose of a warm floor
Underfloor heating is used as the main source of heating in isolated cases, usually these systems play a supporting role. Floor heating is used either to create zones of increased comfort: on loggias, in bathrooms or children's play areas, or in those rooms where providing heat with a radiator heating system is impractical, for example, on the attic floors of buildings with a common heat circuit.
The most common exception is houses built on insulated Swedish stoves. The cutting off of building structures from the ground and continuous thermal insulation make it possible to use even weak sources of heating, and in this light, underfloor heating seems to be a very effective way of heating. For these purposes, it is most reasonable to use a water heated floor, and at facilities that are difficult to supply with gas and solid fuel, an electric cable. Both of these systems have one thing in common - the presence of a screed, which is enough to heat up once, and then it is enough just to maintain heat without worrying about temperature changes.
At a film heat-insulated floor inertia is much lower. Such a system has a time to reach the operating mode of about 5-7 minutes, but after turning off the heating, the floor cools down almost instantly. It is thanks to this property that the film floor is most preferably used in the arrangement of comfort zones. At the same time, the heating film must not be used in areas where flooding is potentially possible, including in the kitchen. Also, among the shortcomings, one can single out the lowest efficiency compared to other systems, which is due to the lack of high-quality thermal insulation under the heating elements.
Difficulty of installation
Choosing a floor heating system, you can not discount the features of the installation process. For example, a heating film can be mounted by a person without experience in electrical installation and construction work, using a minimum set of tools. Underfloor heating film is supplied in complete kits, accompanied by detailed instructions and everything you need for quick assembly and commissioning.
In turn, the electric heating cable is more difficult to install. On the one hand, the list of products used in the installation is growing, a cable fixing system, special electrical connections and electrical fittings are required. Also, the person performing the calculation and installation must be able to calculate the specific power of the sections, the load capacity of the wiring, correctly draw up a connection diagram with the mandatory installation of a number of protective devices. And, of course, a floating type screed is required, which further complicates the installation of a warm floor.
The most difficult to install is the liquid heating system. Although it does not include electrical installation, the responsibility is much higher: if the electric underfloor heating simply fails, then the leakage of the water coil leads to damage not only to the subfloor and coating, but also to other finishes. On the other hand, modern plumbing systems recommended for installing underfloor heating eliminate the influence of low-skilled workers. The guarantee of durability is ensured either by the exclusion of screeding of joints, which is practiced when installing metal-plastic pipes, or by the absolute resistance of fittings to corrosion, which is typical for systems in which pipes made of cross-linked polyethylene are used. Nevertheless, difficulties with fixing pipes, pouring and reinforcing the screed remain relevant.
Other Features
In conclusion, you should pay attention to a number of non-obvious nuances that can affect the choice of underfloor heating system. For example, the reliability of a water-heated floor is determined by the probability of its failure during the declared service life. For liquid systems, this indicator is almost absolute, while the fault tolerance of film and cable heaters with a declared durability of 10-15 years is 50-70%. At the same time, the film floor is relatively easy to repair, while replacing the cable requires dismantling the subfloor.
There is also a lot of controversy regarding the level of noise generated during the operation of different systems. For example, the noise of a water-heated floor can only form when air appears in the circuit, which is solved by automatic gas vents and pipes with an oxygen barrier. At the same time, the electric warm floor makes noise due to the sound (mechanical) action of the electric current, but in the case of using a heating cable, this noise is much lower and is absorbed by the screed, but the film can generate quite distinct unpleasant sounds. One of the best solutions to this problem is the installation of a voltage rectifier in the circuit complete with a non-polar capacitor connected in parallel, the capacitance of which is calculated based on the total resistance of the heating elements.
