Design and installation of floor heating

By Admin | Heating
26 May 2016
floor heating system ... transition to a low-temperature heat sources such as heat pumps.In recent years, builders rent apartments and houses, as a rule, without finishing, so the cost of installing a "warm floor" is minimized, since in any case it is necessary to pour concrete floors and more practical to do them at once "warm".

growing popularity of floor heating systems is not accidental, because they create close to an ideal profile of the temperature distribution inside the building.No wonder they say: "Keep your feet warm and head - in the cold."Furthermore, at a comfortable temperature floor heating 1-2 ° C lower than the radiator, that reduces heat loss by about 5-10%.Incidentally, the "warm floor" is not a modern invention: the ancient Romans used for heating laid in the floor space of the pipe through which heated air is passed.

Design and installation of floor heating systems require compliance with certain conditions.Firstly, the temperature of the supply water in the floor heating system should not exceed 60
° C, otherwise delamination may flooring and discomfort to the people inside.

Secondly, the temperature of the floor must not exceed the specified values.This is due to the fact that excessive heating of sex negatively affects the health of people, especially suffering from diseases of the feet.In Russia, the temperature was 26 ° C.In Europe, for different areas of the room and various buildings are set different values ​​limit the surface temperature of the floor.For example, in the lobby, the hallway and at the entrance to a residential building floor temperature must not exceed 27 ° C;in the living room, kitchen, pantry, bathroom, shower - no more than 29 ° C;the same temperature determined for offices, schools, churches, etc.In the periphery, adjacent to the walls, the floor area of ​​the premises temperature may be 32, in the pool - 33 ° C.

A combination of underfloor heating with wall and ceiling;at least heated portions of "warm walls" have exterior windows.

Determining heat

Heat output (heat) "warm floor" is dependent on water temperature and pitch pipe laying, as well as the temperature difference between the surface and the air in the room.To determine its value can be calculated by using the ready-made or tables.

must say that the underfloor heating manufacturers recommend different temperature differences direct and inverse water, for example, 5 or 10 ° C.The smaller this value (at the same step, laying the pipe), the higher the heat the floor (the average temperature of the coolant above), and the temperature gradient is less (the floor is heated more evenly).At the same time at a lower temperature difference needs greater coolant flow, and, accordingly, it is necessary to apply a larger diameter pipe, which leads to a rise in the cost of the system.Possibly, the temperature difference of 8 ° C is some 'middle'.

installation and commissioning of the system

There are several options for laying "warm floor»:

1. With the use of shaped panels (mat) of polystyrene foam, insulation thickness 15 mm or 30 mm.It is the most convenient and fastest way because once the tube is placed between the projections on the panel, and then poured a layer of concrete.However, the cost of the panel is sufficiently high.I think that it significantly reduced the expansion of the production of such panels in Russia.Coefficient of thermal resistance for 30 mm thick mat is 0.88, and for mats 15 mm thick - m2⋅K 0.45 / W.

2. Laying of pipes on steel mesh, which is placed on a layer of polystyrene.The tube is attached to the grid by means of clips.Top poured concrete.If the floor will be subjected to high mechanical loads, it is also recommended to lay steel mesh top.

3. Laying pipe with special clips that attach the pipe to the insulation layer of polystyrene, which is laid on top of film deposited on its surface lines forming a grid cell with 5 cm. Sometimes a film glued to polystyrene and is available as a standalone product that providesease of installation

4. Laying the pipe using U-profiles: plastic strips with grooves for installation of pipes stick (fasten clips) to a layer of insulation, and on them lay the pipe.

5. When laying pipes in wooden floor joists are nailed to the board;they placed metal "lenses" of heat, which fit into the grooves of the pipe.Of course, in the beginning laid the insulation between joists.

Before laying the basic insulation "warm floor" on the perimeter of the room is necessary to lay a special side insulation that compensates for thermal expansion of the concrete slab floor.If possible, penetration of moisture through the layer of concrete to isolation, for example in the case of the device "warm floor" above the basement, under the insulation is necessary to lay a polyethylene film.The concrete substrate must be cleaned and if necessary aligned.If the basement is not heated, it is recommended to use an additional layer of insulation.

It will be understood that when casting concrete floors is recommended to use a special structure and to improve the adhesion to the concrete pipe to add a plasticizer.

can recommend the following composition: 50 kg of cement (CEMI 32.5 R, according to DIN 1164), 225 kg of sand (0.8 mm), 18 l water, 0.5 l (600 g) of the plasticizer.After pouring screed recommended "provibrirovat" - to eliminate air "pockets" between the pipe and concrete.

height of the concrete layer above the pipe is usually 3-7 cm. Too thin soi can collapse and too fat - leads to a large inertia of the system.When the length of the plate 10 m or greater than 45 m2 area necessary to provide joints between boards with a minimum thickness of 5 mm.When passing through the pipe joints must be protected corrugated tube.

Note that after mounting and connecting the tubes to the headers, before pouring the concrete, it is necessary to hold pressurize the system pressure of 10 atm for 24 hours. When the pressure in the filling system should be at least 3 atm.

Start system is carried out only after complete drying of concrete (about 4 days per 1 cm thickness of the screed, t. E. For drying screed thickness of 5 cm must be 20 days).Do not use the floor heating system to accelerate the drying of the concrete.After starting the system can increase the daily water supply temperature at 5 ° C.

as better use of metal and plastic pipes, for example, Henco, Size 16 × 18 × 2 or 2.They are impervious to oxygen, have relatively small linear expansion coefficient - 0.025 mm / (mK) (8 times less than that of the plastic tubes) and high thermal conductivity - 0.43 V / (mK) and retainshape when bent.

length of one circuit, as a rule, not exceed 100-120 m loss - 20 kPa;minimum water velocity - 0.2 m / s (to avoid the formation of air pockets in the system).

recommended to avoid the use of fittings or, at least, to use fittings, not corrode when in contact with concrete (e.g., PVDF press fittings).Typically, in modern systems the pipe loops are connected directly to the collectors of which are integral valves to change the flow of coolant in dependence on the air temperature in the room and flow (y Henco - V-06-F), or the control valves (V-06-R) for hydraulic balancing loops.

collectors installed on the valve actuators connected to the central controller.Each indoor room temperature sensors are placed, which by means of an electric cable or radio signal is transmitted to the central controller.By increasing the temperature in the room above the predetermined actuator shuts off the water in the circuit.

Units mixing

As already mentioned, the temperature of the water supplied to the underfloor heating system should not exceed 60 ° C;in practice it is usually less than 40 ° C.Perhaps only heating heat pumps are constantly working with these parameters.

temperature water supplied from the boiler and central heating system and reaches above 95 ° C.It is therefore necessary to provide podmes of the return line.Nodes mixing can be implemented using a two- or three-way valves.Now, many manufacturers switched to producing ready-mix units, which is very convenient for installation.As an example, the node VL-PGKT (Henco).It is equipped with a three-way thermostatic mixing valve, circulation pump and safety thermostat to turn off the pump if the water temperature is too high.Currently available as mixing components, combined with the collectors.For example, the module Hencomfort VL-HC connectable 1 to 16 contours.It includes a built-in circulating pump, valves, adjusting valves, safety thermostat.

temperature control

In principle, the floor heating system has the property of self-regulation as a decrease in the difference in air temperature and heat flux decreases floor, but the lack of controls could lead to overheating of the floor surface.The following kinds of control:

1. The temperature of water supplied is changed in accordance with changes in the outdoor temperature, for example, using an underfloor heating system as primary.Thus, as in the case of radiator heating, energy savings and better control valves on the headers.

2. The water flow in the circuit is reduced (or completely stops) when the setpoint temperature in the room.Water inlet temperature remains constant.Adjusted by the valves on the manifold.

3. Water consumption in the circuits decreases with increasing temperature of the return water to the set on the regulator (thermostatic valves or RTL Multibox-RTL) values.Such a system is generally used for small spaces, such as bathrooms, toilets, hallways, etc.Its advantage lies in the simplicity and low cost.

4. Regulation of the flow of water by means of a sensor installed in the floor.This option is suitable for swimming pools, showers, children's rooms, etc., when priority is given to a comfortable floor temperature.

5. Combined systems, which are different combinations of the preceding embodiments.

In most cases, especially when high-temperature heat sources are used for regulation of the air temperature and the temperature in the "return pipes";the supply water temperature in this case - is constant.

Formulas for calculating

Water consumption in the circuits is calculated using the formula G = 3,6 ⋅ Q / 4,19 / ΔT, kg / h where Q - heat loss from the room (or part of the heat loss in the sharing of "warm floor"with a radiator heating) W;ΔT - temperature difference between the feed and return water (typically between 5-10 ° C).

Since loops are of varying length and costs necessary to carry out hydraulic balancing (linking) loops.

Linking held or adjusting valves on the calculation of the pressure loss, or for the issuance of the design flow in flowmeters (flowmeters) in the sewers.This method is more convenient.

pressure losses in the pipe can be calculated by the formula

? P = L ⋅ R, Pa,

(L - length of the circuit, m; R - Linear pressure drop, Pa / m.)

also results in a formula to determine the lengthloop:

L = F / b,

where F - the floor area in m2;b - step laying the pipe, m.

Configurable loop

Pipeline loop of floor heating can be laid in various ways.The easiest - "snake", but laying a loop at the beginning of the floor will be warmer than at the end (due to the higher water temperature).When laying the spiral flow and return lines run parallel to each other, so the temperature of the floor evenly.At a constant temperature water and heat, respectively, the temperature of the floor surface can be varied by varying the pitch of the pipe laying.So, the external walls of the tube is sometimes placed in smaller increments.

For heating these zones You can also use a separate circuit.The specific geometry depends on the specific objectives and purpose of the premises.

Recall that heat "warm floor" can be found on the tables - depending on the installation steps, the water temperature and the type of coverage.

Calculation example

Suppose that you need to design a system of underfloor heating the apartment area of ​​70 m2.The area of ​​individual rooms:

kitchen - 10;WC - 6;vestibule - 4;bedroom - 20;Area - 15;

living room - 15 m2.In the kitchen, in the bathroom and hallway tiles laid, and in the other rooms - flooring.The temperature in every room shall be maintained at 20 ° C;

water temperature in the heating system - 45 ° C.

preselected step laying pipe 0.2 m, use the table to determine the specific (1 m2) floor heat with a different cover.By calculating this value after heat "warm floor" for each of the facilities, the designer is able to solve the question of the need for additional installation of radiators.

Calculate water consumption for metal pipes 16 × 2, the length of the circuit, the pressure loss in the circuit and the speed of the water in the pipes, you can use a computer program Rissert-Calc.These calculations are presented in Table.2. The rate of water for bathrooms and hallway was too low (less than 0.2 m / c), so it makes sense obediniteti contours into one.Pressure losses bedroom slightly above 20 kPa, so here, on the contrary, should be designed to use the two circuits or pipes of large diameter - 18 × 2, whereas the pressure loss was 10.8 kPa and the water speed - 0.3 m / s.

calculates the underfloor heating system is most convenient with the help of a special computer program.The most "advanced" of them are based on AutoCAD and allow the paint system and make detailed calculations (one of these programs is designed Henco).For preliminary calculations, as well as calculations of small systems can use a simple program, for example, Rissert-Floor and Henco-Floor, which allow to get ready for the specification of the necessary equipment and provide useful information about the system.

Aqua-Therm number 5 (33) 2006