- Underfloor heating types
- Appointment of underfloor heating
- Complexity of installation
- Other features
Underfloor heating in one form or another is 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.
Underfloor heating types
To begin with, it is important to agree on 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 it is fenced from other building structures with 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 from a thin pipe, laid along the entire plane of the heated area. The problem with the water floor is that the heating is carried out only along the pipe laying line, so they are hidden under a sufficiently 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 underfloor 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 heated water floor cannot work, and the maximum pipe length in the loop is 100-130 m.
Cable underfloor heating is similar in design to a water one, but instead of pipes with a heat carrier, a cable with high resistivity is used. In installation, such a heating system is simpler, but at the same time it is necessary to calculate in advance the length and resistance of the cable at each heating section in order to provide the necessary heating power. The main disadvantage of electric heating with a cable is a low service life – 15–20 years versus 50 for a water heated floor. Among the other disadvantages, the most pronounced are the requirements for high power electrical connections, 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, a distinction is made between single-core and two-core heating cables, which have no other differences except for the connection and installation diagram.
Film heated floor is sometimes called infrared, which is not entirely correct, because any of the heating systems described above is capable of emitting heat. Such a misconception arises for the reason that a heating film, and this is really the most common heating element of a resistive type, does not transfer heat directly to the screed, as a cable or pipe with a heat carrier does. The film is not walled up in the screed, but is placed under the covering, 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 power density, low service life, comparable to the floor covering itself, as well as the impossibility of such heating device under materials requiring attachment to the base: parquet, ceramic tiles or porcelain stoneware. Additionally, we note that there are films with carbon and bimetallic heating elements, although there is no fundamental difference between them..
Each of the types of underfloor heating must first of all be considered from the point of view of the admissibility of its use in certain conditions dictated by the features of the building structure, fire and electrical safety requirements, as well as the rules of operation of the used floor coverings.
In this regard, a water-heated floor has the greatest number of restrictions on its use. For example, it cannot be connected to a municipal heating system, and it is also prohibited to install water underfloor heating on floors under which the living quarters are located. Liquid underfloor heating is the only type of 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 for heat distribution and for protecting the coil, which is extremely vulnerable to mechanical damage..
Both types of electric underfloor heating are most beneficial to use on objects that do not have their own liquid heating system or are connected to central heating. The advantage of a heating cable over a water-heated floor is the ability, without additional efforts, to provide a tighter laying of heating elements, which in the case of a tubular coil is impossible due to the 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 location of heating zones on the floor is determined once during installation, which limits further redevelopment and reorganization of premises. It is believed that the presence of heating under the furniture does not have a negative effect on it due to the relatively low operating temperatures, but this does not definitely add to the durability of the system itself. In addition, the heated area where the furniture is installed is automatically excluded from the heating system. The film floor does not have this drawback: the placement of the heating elements is quite easy to change by temporarily dismantling the floor covering.
Appointment of underfloor heating
Underfloor heating is used as the main source of heating in isolated cases, usually these systems play an auxiliary 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 it is impractical to provide heat with a radiator heating system, for example, on the attic floors of buildings with a common thermal circuit.
The most common exception is houses built on Swedish insulated slabs. Cutting off building structures from the ground and continuous thermal insulation allow using even weak sources of heating, and in this light, a warm floor appears to be a very effective way of heating. The most reasonable for these purposes is to use a water heated floor, and at facilities that are difficult to supply with gas and solid fuel – cable electric. Both of these systems have one thing in common – the presence of a screed, which is enough to heat it up once, and then it is enough just to keep warm without worrying about temperature changes..
Film underfloor heating has a much lower inertia. Such a system has a time to reach the operating mode of about 5–7 minutes, but at the same time, after turning off the heating, the floor cools down almost instantly. It is due to this property that the film floor is most preferable to use when arranging comfort zones. At the same time, it is forbidden to use the heating foil in areas where flooding is possible, including in the kitchen. Also, among the disadvantages, 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.
Complexity of installation
When choosing a floor heating system, you cannot 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. Foil underfloor heating is supplied with fully complete kits, accompanied by detailed instructions and everything you need for quick assembly and start-up..
In turn, the electrical heating cable is more difficult to install. On the one hand, the list of products used for installation is growing; a cable fixation system, special electrical connections and electrical fittings are required. Also, the person carrying out 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 of 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 an electric underfloor heating simply fails, then a 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 the installation of underfloor heating, exclude the influence of low qualifications of workers. The guarantee of durability is provided either by the exclusion of brickwork in the screed, which is practiced when installing metal-plastic pipes, or by the absolute resistance of the 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..
In conclusion, you should pay attention to a number of non-obvious nuances that can affect the choice of a warm floor 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 by the operation of different systems. For example, the noise of a heated water floor can be generated only when air appears in the circuit, which is solved by automatic gas vents and pipes with an oxygen barrier. At the same time, an electric warm floor makes noise due to the sound (mechanical) action of an 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 distinguishable unpleasant sounds. One of the best solutions to this problem is the installation of a voltage rectifier in the circuit complete with a parallel connected non-polar capacitor, the capacity of which is calculated based on the total resistance of the heating elements.