- Underfloor heating device
- Do-it-yourself electric underfloor heating
- Do-it-yourself installation of a water-heated floor
- Combined floor heating systems
The “warm floor” system is no longer a wonder. This article will help you understand not only the principle of operation of a water and electric underfloor heating, but also carry out its installation with your own hands. This will significantly reduce financial costs and avoid possible errors during the installation process..
Comfort in our home is inextricably linked to warmth. Living without a comfortable room temperature is not only uncomfortable, but also unsafe for human health. In this article, we will consider an option for a heating system that is very popular with consumers – underfloor heating (electric and water). After getting acquainted with this material, you will learn much more information about warm floors than by looking at ordinary advertising brochures. What are the main parts of a warm floor, how is it installed, what are the features of using such systems – we will talk about all these aspects in the article.
Underfloor heating has a long history. Naturally, in ancient Rome, it was not about modern electric underfloor heating, however, the principle of floor heating in a Roman bath is the same as when floor heating is used. The smoke from the stove passed through special channels under the floor and heated the room. In addition, the stones retained heat for quite a long time, which made it possible to more economically use the burnt material. With the advent of steam (water) heating, this principle of space heating has not been forgotten either. Underfloor heating, which is heated with water, is widely used today. In the past 30-40 years, electric underfloor heating has been very popular..
Roman Bath in Beirut
There are a lot of reasons for this – from ease of installation and maintenance to durability and low cost of electricity. Moreover, in a cold climate (Scandinavian countries, the extreme north of our country, etc.), an electric warm floor becomes simply an irreplaceable option for space heating. There are also options for combined heating – underfloor heating and water heating. This allows you to significantly reduce energy consumption during the heating season..
Let’s see what is the fundamental difference between underfloor heating and traditional water heating. First of all, it is comfort. Let’s remember how traditional heating works. The radiator is placed on one of the walls of the room, most often under the window, since this is where the greatest heat losses occur. Warm air rises, thereby displacing colder air, which, in turn, heats up as it passes through the heating radiator. The most comfortable temperature will be 1.5-2 meters from the radiator. Heating of the room with traditional heating is uneven. The principle of operation of a warm floor is somewhat different.
The heating area of the room is many times larger than the area of the heating radiator, since the heating element is usually laid over the entire area of the room. It is enough to remember the old adage that you need to keep your feet warm, and it immediately becomes clear that no other type of heating will create you such comfort in the room as a warm floor. However, there are certain pitfalls here too. This is due to the fact that the temperature range at which a person feels comfortable is very small (from 25 to 28 degrees). The comfort zone in the room seems to change and is located not at a certain distance from the heater, but at a certain height along the entire perimeter of the room (connected with the laying of the heating cable). The comfort temperature zone is located in the lower part of the room at a height of up to 1 meter from the floor. There are cooler layers of air at the top of the room..
However, this does not cause discomfort in a person, which is due to his physiology. In addition, the warm floor allows you to quickly and easily change the temperature in the heated room – just one turn of the temperature regulator knob or the command of the “Smart Home” system will be enough for this. It should be noted that this applies only to electric underfloor heating. In the case of using water or combined underfloor heating, quick adjustment of the room temperature will not be possible. In addition, do not forget that such factors as the presence of furniture in the room, carpet on the floor have a significant impact on the effective operation of a warm floor. This is due to the fact that any material has a certain thermal conductivity (measured in W / (m · K)). This indicator is important for us not only when choosing thermal insulation, which will avoid heat loss, but also when choosing a material that will cover the heated floor itself and on which we will walk (linoleum, parquet, laminate, tiles, etc.).
Underfloor heating device
The device of a warm floor is quite simple. Both water and electric floors are mounted on a special heat-insulating material, then they are poured with a cement-sand mortar, tiles, linoleum or any other floor covering are laid on top of the resulting screed. The heat source will be either water or a special electrical cable. Here we will talk about the device of this electric heating cable in more detail..
1 – overlap; 2 and 7 – cement-sand screed; 3 – thermal insulation; 4 – mounting tape; 5 – temperature sensor; 6 – heating cable; 8 – ceramic tiles; 9 – thermostat
Externally, the cable for the “warm floor” system resembles an antenna cable. But its purpose is not to transmit a signal (electricity) over a distance, but to convert electrical energy into heat. A very important parameter that characterizes a warm floor is its specific heat release. For different manufacturers, this figure ranges from 15 to 25 W / m. At the same time, do not forget that the insulating layer that covers the heating element itself is able to withstand heating up to temperatures above 100 degrees, which is very important, since most often the cable is poured with a screed and it must give off heat, while not harming the insulating layer.
Underfloor heating cable design: 1 – insulation of current-carrying conductors; 2 – heating conductors; 3 – drainage conductor (grounding); 4 – foil screen; 5 – external insulation
If the cable overheats, the insulating layer will be broken and a short circuit is possible. Repairing a warm floor is a rather troublesome and expensive task, since it is almost impossible to pinpoint the exact location of cable damage. It is for this reason that you should not choose a cable with a higher specific heat release and during installation it is necessary to observe the recommended distance between the threads, as this can also cause overheating and short circuit of the heating cable. These breakdowns are excluded in the case of using a water floor heating. But there may also be some complications, for example – cracks in pipes, fittings and, as a result, a coolant leak. Such an emergency in a private house will not have any special consequences (you just can damage your property), but if such a breakdown occurs in an apartment building, then you may have to compensate the neighbors for the results of flooding their apartments. A well-executed waterproofing can minimize possible troubles in case of emergencies. However, if a warm water floor is connected to a central heating system with a high coolant pressure, then waterproofing will be of little help..
Do-it-yourself electric underfloor heating
Let’s analyze the procedure for installing a warm floor on our own. First of all, you need to decide for what purpose a warm floor is purchased – as additional heating in an apartment, as a heating system on a glazed loggia, etc. Consider as an example the installation of a warm floor in an apartment (room) as additional heating.
Quite often, underfloor heating is installed in the kitchen and in the bathroom, since it is there that it is possible to lay the heating cable under the tiles (this is the most common method of installing a warm floor).
As additional heating, 100-120 W per 1 m will be enough for you2 the area of the room, subject to the mandatory use of good quality thermal insulation material. For a kitchen with an area of 10 m2 you will need about 45-50 meters of cable (the seller can provide you with this data for sure, since the power of the heating cable is different). It is also worth checking with the seller the minimum permissible distance between the heating cable threads (this is necessary in order to avoid local overheating of the cable).
Before laying the heating cable, it is necessary to free the room from furniture, remove the old floor covering and carefully prepare the floor surface – level it, remove construction debris, and, if necessary, make a thin cement screed. After that, you need to prepare a place on the wall for installing a special electric thermostat, with which you will regulate the temperature of the warm floor. If necessary, equip a separate wiring for connecting the underfloor heating. After completing these preparatory work, you can proceed with the arrangement of thermal insulation and the direct laying of the heating cable. Some masters advise, in addition to thermal insulation, to make waterproofing in order to avoid the formation of condensation near the heating cable. A polyethylene film is used as waterproofing. Modern building materials allow you to minimize the loss of usable space (do not forget that thermal insulation, cable, cement screed – this all together reduces the useful volume of the room).
So, penofol is quite often used as thermal insulation – a modern heat-insulating material with a special coating of foil about 14 microns thick and polyethylene foam with a self-adhesive layer. This material is very thin and light, while the thermal conductivity of penofol is 0.049 W / (m · K). Penofol is supplied in rolls, after laying the foam foil upwards, it is necessary to glue the joints between the rolls with a special assembly tape. After the insulation is completely laid along the entire perimeter of the room, a thin reinforcing mesh is laid on top of it, the main task of which is:
- to exclude overheating of the cable from contact with thermal insulation;
- give strength to the cement-sand mortar, which will be poured into the floor.
The cable is installed using an assembly tape, which is fixed to the floor. This tape allows you to eliminate kinks, to observe all the distances between the cable loops. The cable is laid with a step of about 20-25 cm. Normal operation of an electric heated floor is impossible without installing a special temperature sensor. It is necessary to provide for the possibility of its replacement without subsequently destroying the concrete screed. For this, the thermal sensor is usually installed in a special tube, which is poured together with the cable with a cement screed..
Before pouring the installed underfloor heating, they check it, check again the correctness of the entire installation and the reliability of the connections.
There should be no errors at this stage, since to eliminate them, you will have to dismantle the cement screed. The serviceability and performance of the underfloor heating can be checked not only by applying voltage to the heating cable, but also by measuring the cable resistance using a special tester. All parameters of such measurements are indicated by the manufacturer in the product passport. After checking, a cement screed is made up to 3-4 cm thick. The pouring should be carried out evenly, special attention must be paid to ensure that no voids form in the screed, as this can lead to overheating and failure of the heating cable. After you have done the fill, you need to wait until it dries completely..
If work on laying the floor covering can be started after 4–5 days, then the control check of the performance of the warm floor can be carried out no earlier than after 30–35 days. And the point is not at all that a damp screed can cause a short circuit and make the heating cable unusable. Most materials expand when exposed to high temperatures and contract at low temperatures. Any material has its own coefficient of thermal expansion. If the underfloor heating is turned on until the concrete screed is completely dry, uneven drying of the mortar will occur, the formation of cracks and voids in the screed, which we fought so carefully during the pouring. This will increase the risk of premature failure of the heating cable. It is also worth considering the location of the furniture in the room and not laying the heating cable in the places where it will be placed..
Do-it-yourself installation of a water-heated floor
The installation of a warm water floor is carried out in approximately the same sequence as the installation of an electrical one. However, do not forget that water and electric heating are subject to different laws of physics. If an electric heating cable has the same (or almost the same) temperature along its entire length, then the situation is somewhat different with a water floor. We have already talked about how the heating medium (in this case, water) is heated using a variety of heating devices – electric and gas boilers, boilers for liquid and solid fuels, etc..
The coolant will have a maximum temperature immediately upon entering the heating system from the boiler heating chamber. Circulating through the system, the water gradually gives up its heat and returns to the boiler, already significantly cooled, which means that the coolant that will circulate through the underfloor heating system will have different temperatures at the inlet and outlet. With improper installation, you should not wait for effective work, since the room will warm up unevenly. We will tell you a little later how to avoid mistakes when installing a water heated floor, so as not to violate the description of the sequence of work performed.
There are several options for laying a water-heated floor:
- concrete installation system (most common today);
- floor system.
The wall-mounted installation system for a water-heated floor is, in turn, divided into:
- polystyrene foam installation system;
- wooden installation system for underfloor heating.
The concrete installation system for a water underfloor heating (the same as the above-described system for laying an electric underfloor heating) is most widespread due to its low installation cost. All installation work is carried out in several stages. The sequence of work and materials are used the same as when laying an electric underfloor heating. Pipes of a water-heated floor are not afraid of overheating, unlike an electric cable.
However, their installation must be performed not only carefully, without strong bends and fractures, but also in a strictly defined sequence. In this case, a lightweight reinforcing mesh is not suitable; it is necessary to use reinforcement with a diameter of 4–5 mm, the mesh size is about 150 mm. This is due to the fact that the water heated floor has a fairly significant weight. The pipe-laying step can be very different (water pipes are not afraid of overheating), but in any case, the distance between the pipes should not be more than 300-400 mm, as this will significantly reduce the efficiency of this heating system, and will also lead to the appearance of cold stripes on the floor – areas of the floor with a lower temperature. Pipes are fixed to the floor with dowels and clamps.
In practice, several options for laying pipes for a water-heated floor are used:
- Snake (parallel method).
- Meander (double snake).
It would be wrong to recommend any one method of pipe laying as the most effective. When installing a heated water floor, a number of factors should be taken into account, including external walls, the presence of window openings, etc. – it is in these places that pipes with a hotter coolant should pass.
The length of one loop of pipes of a water-heated floor (from entrance to exit) should not be more than 100 m, due to the fact that the system will have significant hydraulic losses and such a floor will not work effectively. 1 m2 the area of the room is about 6–7 running meters of pipe. It depends on the distance between the pipes.
Both ends of the pipe (supply and return) are led into a commutating (collector) cabinet. This cabinet is mounted either in a special niche in the wall (it has yet to be cut down), or it is made overhead (open). The placement of the collector cabinet depends only on your desire and capabilities (arranging a niche in the wall is a rather expensive type of work). The manifold cabinet will contain not only pipes, with the help of which the warm floor is connected to the main heating circuit, but also valves that will allow not only to shut off the coolant, but also to regulate the floor temperature in the room.
The temperature can be adjusted not only manually, but also using a special electronic valve that will respond to signals from the temperature sensor (the temperature sensor is installed in the same way as when installing an electric floor heating). This leads to a rise in the cost of the system, but it is more convenient during its operation, since it makes it possible to connect a water heated floor to the “Smart House” system. This system will not only allow you to control the temperature in the room, but also save you from a flood that can happen when the heating pipes are leaking..
Before pouring the pipes with a cement screed, it is necessary to pressurize the entire system in order to exclude possible leaks of the coolant.
The leveling system of the underfloor heating water allows you to exclude the arrangement of the cement screed from the installation process. This not only speeds up the process of putting the floor into operation, but also significantly reduces the cost of possible repairs. Moreover, this system is much lighter than a traditional water-heated floor, which can significantly reduce the load on the floor slabs, the supporting structures of the building (weight 1 m2 traditional concrete water underfloor heating is about 250–350 kg, while the weight of a floor water floor is about 35–50 kg, depending on its type). There is one significant remark – you cannot connect a water-heated floor to a centralized heating system without prior agreement with housing and communal services and heat supply organizations.
Combined floor heating systems
These systems are most often found in those houses where a water floor heating plays the main role in heating. In spring or autumn, there is always a period of time when it makes no sense to turn on full heating in the house (the microclimate is quite favorable), but to create even more comfortable conditions it will not be superfluous to slightly increase the temperature in the room.
If in houses with individual heating it is still possible to turn on the heating independently and adjust it to the minimum temperature regime, then in houses with central heating this is not possible. This is where a combined warm floor will come to your rescue, the electrical part of which will create a favorable microclimate in your apartment. Installation of such a floor is carried out in the order that we wrote about above. Do not forget that the simultaneous operation of an electric and a water heated floor can lead to overheating of the heating cable. These features should be taken into account when installing this structure..
We hope that this article will help you make a successful, profitable and correct choice, and the purchased equipment will delight you with flawless work..