We make a water heated floor from a gas boiler

Giving preference to autonomous heating methods, homeowners want to solve the problem of heating an apartment or house once and for all. Independent heating provides not only optimal temperature conditions in residential premises, but also provides significant cost savings in the family budget. It is up to you to decide which type of autonomous heating to give preference to. To begin with, let’s get acquainted with the main existing options for home heating, based on the energy they consume:

• Electrical devices.
• Solid fuel devices.
• Liquid fuel units.
• Gas appliances.

Each of the listed groups is divided into subgroups according to the installation method, the coolant used, the scope, etc. But to this list of devices used as the main means of heating housing, it is necessary to add systems involved in the heating process as additional devices that increase comfort temperature regime in the room. Such systems include the so-called underfloor heating, electric and water.

Be sure to read: independent heating in the apartment.

Of particular interest in this regard is the water-heated floor, which operates from a gas boiler — an autonomous hot water generator. The system is relatively new, but sufficiently studied, superior in efficiency to devices such as, for example, heated fans.

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Underfloor heating — idea and concept

The idea of ​​underfloor heating in living quarters is not new. A person has long paid attention to the laws of physics operating around us — warm air in a room always accumulates at the top, under the ceiling. The cooled air, on the contrary, sinks down, making the floor the coldest place in the room, eating up precious kilocalories with its large area.

The floor artificially heated to a certain temperature becomes a powerful source of heat in the room. Due to the large heating area, the air evenly warms up and rises, filling the entire interior space. The process of air exchange provides the necessary temperature in the room, and, moreover, minimizes the difference between its values ​​at the floor level and under the ceiling. In rooms equipped with underfloor heating, there are practically no zones with cool air.

Gas boilers used today for home autonomous heating are quite capable of ensuring the normal operation of a warm water floor. It is possible to achieve an effective increase in comfort in this situation, subject to certain conditions — accurate thermal and hydraulic calculations, competent installation of the underfloor heating system.

Concept

It is possible to provide floor heating by laying a pipeline in the existing space between the floor and the floor covering, in which the coolant heated by the gas boiler will circulate. Water (regular or with special anti-freeze additives) acts as a heat carrier — a traditional liquid used for autonomous boiler equipment.

The heat exchanger in this case is a pipeline laid under the floor covering. The effect is achieved due to the large heat transfer area. The amount of heat entering the interior space is sufficient for the horizontal and vertical distribution of the warm air mass.

Important! The fundamental difference between this system and other types of heating systems is the low temperature of the coolant. For a warm water floor, it is enough to heat the coolant to a temperature of 30-50 ⁰ FROM.

Components of the «warm water floor» system

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The main structural elements of such a system are:

• gas boiler;
• pressure pump;
• shutoff valves and connecting fittings;
• the main pipeline for distributing the coolant to residential premises;
• floor mini-pipeline for laying on the surface of the subfloor;
• collector;
• system of automation and adjustment of operating modes.

Gas boiler

For a private house of a large area, where it is planned to increase the comfort of the temperature regime in a large number of rooms, the best choice would be a stand-alone double-circuit gas boiler. Such units have high power, are able to simultaneously solve several problems at once — heating residential premises and providing hot water.

On a note: for floor-mounted gas heating equipment, it is necessary to equip an appropriate room with a chimney and ventilation. The room allocated for the boiler room (boiler capacity up to 30 kW) must have an area of ​​​​at least 4 square meters, and a minimum volume of 8 cubic meters. If a single-circuit gas boiler is used for underfloor heating, then for the DHW system it will be necessary to additionally install an indirect heating boiler, which can be placed in the same room.

For an apartment where every square meter of area is expensive, you can use a wall-mounted gas boiler, which, with the right power selection, will also ensure the efficient operation of a water-heated floor. Due to its dimensions, it is easier to choose a place to place such equipment; wall-mounted gas boilers can be installed even in the kitchen or in the bathroom. Typically, the power of wall-mounted gas boilers varies in the range of 7-30 kW.

Wall-mounted autonomous gas appliances in most cases have a closed combustion chamber, therefore, for its efficient and safe operation, it is enough to equip a coaxial chimney with access to the street or to the central chimney shaft.

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An important point when buying equipment is to determine the optimal power of the gas boiler, which will have to ensure the operation of the «water heated floor» system, therefore, when choosing a gas boiler model, it is necessary to rely on thermal calculation data.

For reference: for heating 1 sq. m of living space requires the cost of approximately 100 W of electricity, subject to good thermal insulation of the room, ceilings no more than 3 m high and no excessive number of windows.

Most of the premises of a private house have external walls in their construction, heat losses through which may require an increase of up to 150 W of heat consumption for heating 1 sq. m. living area. Therefore, when buying a gas boiler, even having a thermal calculation indicating the required power of the unit, it is better to purchase a device with an excess of the calculated value of this characteristic by 15-20%.

In most cases, the power of double-circuit boilers is designed for hot water supply with one or two water intake points. Therefore, with an increase in the number of hot water intake points, an increase in boiler power will be required.

In this respect, a water-heated floor has an advantage — it loads a gas boiler in a gentle mode. The principle of operation of the underfloor heating system in this situation requires minimal energy consumption from the boiler to heat the coolant. Most of the boiler power is released to heat the water of the hot water supply system.

Pipes for water floor heating

For laying a warm water floor, copper, polypropylene, metal-plastic or PEX pipes are used.

Copper pipes (high thermal conductivity, durability) are an ideal material for underfloor heating, so their price is high and availability is limited.

Polypropylene pipes are also not very common, but for a different reason — their flexibility is insufficient, and the minimum bending radius of the pipe should be equal to 8 of its diameters, which moves the turns apart.

Pipes made of metal-plastic are deservedly popular — the inner aluminum coating provides them with good thermal conductivity, and polymer shells protect them from damage. With such characteristics, an affordable price is a good incentive to choose in their favor.

PEX pipes are a material made of “cross-linked” polyethylene, that is, with an artificially modified molecular structure that makes this material strong and durable. The price of PEX pipes is quite affordable, and therefore their use in the installation of water-heated floors is widespread. However, one specific property of this material should be borne in mind — when heated, PEX pipes tend to take on their original contour, therefore, when laid on the floor, they must be firmly fixed to the screed reinforcement.

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The heating system does not fit in one day, so its reliability, including tightness, and durability must be ensured. For this purpose, the pipes are laid in a single solid coil, without joints. The task is to obtain a single, closed circuit during the installation process, through which the coolant will circulate, for which it is better to use water with special additives. This will avoid defrosting the system during severe frosts. This measure is relevant for owners of country houses and cottages with non-permanent residence.

Important! When used in a water system, it is necessary to install an additional protective device, a compressor or a compressed air cylinder for emergency purging of the entire circuit and draining the coolant.

Important! When buying pipes for a heating system, pay attention to the markings. Products intended for heating systems have the corresponding symbols and designations. As a rule, this is an allowable pressure of 10 bar and a heating temperature of up to 95 ⁰FROM.

Depending on the characteristics of the room and the type of flooring (thickness of the screed, height of the room, etc.), pipes with a diameter of 16-20 mm are used to install the underfloor heating system. During the laying of the pipeline, a minimum bending radius is allowed, equal to five times the diameter for metal-plastic pipes and 8 times for polypropylene material.

To complete the picture, we suggest that you familiarize yourself with the video material, which describes in detail and shows how the installation of a water-heated floor is carried out.

Installation of the «water heated floor» system

The installation of a water-heated floor system begins with the preparation of the foundation, which includes several operations, which we will briefly consider now. Failure to comply with the requirements for the subfloor, on which the heated floor is mounted, is fraught with at least a decrease in the efficiency of its work, at the maximum — depressurization followed by expensive overhaul.

Foundation preparation

The substrate must be properly prepared before laying the pipeline. The base surface must be firm, clean and even. Height differences are allowed in the range of plus or minus 10 mm per meter of linear length. If the floor surface does not meet the requirements, has a large curvature and obvious flaws, a leveling screed is installed, followed by waterproofing of the base in case of depressurization of the system.

Before laying the pipeline, thermal insulation of the subfloor is also carried out. For these purposes, plates made of extruded polystyrene foam, or basalt fiber 30-50 mm thick, are used.

With a sufficient budget, the use of plates shielded with foil and equipped with special protrusions for convenient pipe laying is justified. Such measures are resorted to to reduce heat losses through the floor in the premises of the first floor — a warm floor, together with a gas boiler of any capacity, will work with an increased load simultaneously with floor heating to heat the basement or someone else’s apartment on the floor below.

Important! Before pouring the laid pipes of the underfloor heating system with cement mortar, it is necessary to stick a strip of damper tape 5 mm thick and a width equal to the thickness of the poured mortar layer along the perimeter of the room on the walls. The tape will compensate for the thermal expansion of the screed and reduce its pressure on the vertical structures.

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Mounting

Underfloor heating systems are divided into 2 types according to the design and, accordingly, the installation method:

• concrete (filled);
• flooring.

In the first case, we are talking about pouring with concrete the contour of the system of water heated floors laid on the prepared base. This operation is preceded by breaking down the base into sections and laying the reinforcing mesh.

The following types of laying pipes-heat pipes are used:

• snake;
• double snake;
• spiral;
• offset spiral;
• combined method.

The diagram shows how the heating circuit is laid in a room with increased heat loss — two or more external walls.

Important! After the installation of the underfloor heating system is completed, it is pressure tested at a pressure of 5 bar for 24 hours.

The concrete screed acts as an additional element-participant in the process of heat distribution. Considering the poor performance of concrete in tension, it is placed at a pressure in the heating system of 3 bar, reducing the tensile load with further water supply to the operating pressure.

For the screed solution, cement of a grade not lower than M-300 is used, and its thickness should be 30-50 mm, while the mortar layer above the heat pipes should not be more than 2 cm.

When installing a system of water-heated floors, one should take into account the technological limitation — a finished floor covering must have a high coefficient of thermal conductivity in order to transfer heat into the room air with minimal losses. That is, laying linoleum, laminate, parquet, and boardwalk over a warm floor is not advisable due to the high heat-insulating properties of these materials. And laying on top of a tile system, especially with a high density — porcelain stoneware, natural stone, broomstick, is not only justified, but also expedient because of the constantly cold surface of such a finish.

The laying method of laying is used in rooms where the use of a screed is undesirable due to low ceilings, or the production of concrete work is fraught with moisture leakage into the lower or adjacent rooms. The restriction may be seasonal or be related to the design features of the building. The main advantage of flooring systems is the high speed of their installation. Warm water floors of the floor type of laying according to the materials of the system device are divided into:

• polystyrene;
• wooden:

• modular;
• rack.

All these types of flooring systems are less labor intensive and there is no significant pollution of housing during installation.

Polystyrene underfloor heating

This system is a set of heat-insulating coating made of extruded polystyrene foam (expanded polystyrene), heat pipes and heat-distributing aluminum plates.

Polystyrene plates are laid on the bearing base, on top of which heat pipes are mounted on aluminum plates with special grooves.

On top of the aluminum plates, the floor is finished with a material with a high coefficient of thermal conductivity (for example, ceramic tiles on 2-component epoxy adhesive).

Wooden underfloor heating systems

These devices are mounted on existing wooden floors or logs made of wood.

In the modular version, plates (modules) are used with channels and grooves for heat-distributing plates and pipes.

In the slatted type of underfloor heating, the modules are installed between the logs on the hard subfloor, or the logs are pre-installed for this. These structures play the role of stiffening ribs for a heated water floor and its subsequent finishing, the list of structural elements does not differ from the modular view.

After the laying of underfloor heating of the floor type is completed, the system is also pressure tested and commissioning is carried out (tightness check, tightening of connections).

The flooring method of arranging the underfloor heating system is universal and applicable in almost all buildings and structures. However, its advantages are reflected in the cost, which is quite high.

Conclusion

A competent project combined with a qualified installation of equipment is a guarantee of a positive result. A water heated floor, which you will use as an additional home autonomous heating system, will be an effective, economical and practical device that significantly increases the comfort of your home.