Floor heating. How to make a warm floor from heating? Warm water floor
In our time, you will not surprise anyone with warm floors. They are massively installed in residential buildings, and in office premises, and at working enterprises. If, until recently, heated floors were built most often in bathrooms and hallways, now they have moved to kitchens, living rooms, and bedrooms. Underfloor heating is not only comfort and coziness. It is also a significant part of the overall heating system, which, moreover, has a beneficial effect on the home microclimate. Not only do you get out of bed and walk on warm floorboards, they also heat the whole house, helping ordinary radiators in this.
Underfloor heating - comfort and practicality
(Illustration source: bigbuzzy.ru)
The most popular type of floor heating is the water system. It consists of flexible hollow hoses that are installed directly into the concrete screed or under the deck and connected to the main heating system. The water in the cavity of the hoses is heated and circulates through the loops, giving off its heat to the floor covering.
But we want to tell you about an alternative floor heating system - electric. Although she has not yet received wide application, but with very positive results. Let's try to briefly tell you about the main features of electric floor heating, its positive and negative aspects. Thus, you will be able to find out all the necessary information and accept optimal solution regarding the choice of underfloor heating system.
Underfloor heating is the most common
(Illustration source: ksportal.ru)
The electric floor heating system consists of special heating elements– cables, films or tapes. main feature their functioning - transformation electric current into warmth. Elements can be heated up to 70 degrees, and Additional materials(insulating sheath), in turn, have high heat resistance (over 100 degrees). In general, the system consists of several components: a heating section, materials to simplify and speed up installation (mounting tapes, plastic corrugations), a heat-insulating layer, a thermostat and temperature sensor. All this "beauty" is installed on a rough coating, connected to a source of electricity and fixed in the required position by pouring concrete screed or installing a lag.
The basis of electric heating
(Illustration source: yalta.olx.com.ua)
Before starting the installation of electric underfloor heating, it is necessary to carry out thorough thermotechnical calculations. The choice of appropriate floor heating system materials depends on the result of these calculations. When analyzing, one should take into account the type of final flooring (wood, for example, has a relatively low thermal conductivity compared to ceramic tiles), the dimensions of the room, the thickness of the floor, the optimal allowable amount of electrical power used, the heat-insulating properties of the room and other equally important factors that familiar to experts.
According to the materials of execution, electric underfloor heating is divided into cable and film. Cable electrical systems consist of special two-core cables, which, under the influence of electricity, are heated to the required temperature, giving off heat to the floor covering. Film systems consist of flexible rods made of composite materials and work on the principle of infrared radiation. Usually they are produced in the form of thin mats - films. There is also the so-called rod system which combines water and electricity. In hollow hoses designed to be filled with water, heating cables are pre-placed, which heat the liquid by transforming electricity into heat energy. However, such systems are a novelty in the domestic market and are rarely used in everyday life.
Flexible rods are made of composite materials
(Illustration source: repairmaker.ru)
The main advantages of electric floor heating systems.
Electric underfloor heating, however - like any electric heating, has a high productivity. Such systems quickly heat up and transfer heat to the room, while converting into thermal energy 100% generated electricity.
Electric underfloor heating does not involve difficulties during their installation. They don't connect to central system heating, or to water communications. All you need is a source of electricity. Thus, it can be assumed that the cost of installing an electric floor is not high compared to a water-based floor heating system.
Since electric mats, tapes and cables are sold ready-made, this greatly simplifies their direct installation. The heating elements are fixed with special materials for easy installation (grids, tapes), and their placement is carefully calculated in accordance with the expected power and heating strength. It remains only to roll the roll over the surface, firmly fixing it with a fastening material (adhesive solution) and proceed to subsequent work on laying the flooring.
Installing an electric floor is easy
(Illustration source: postroy-sam.com)
Since there are ultra-thin electric floor systems on the market, they can be installed without screed directly under flooring. This fact is very positive, especially when repair work. In addition, since electric floors do not require additional controls (valves, pipes, heaters), a small temperature sensor with a thermostat can be placed in any secluded corner and they will not spoil the overall interior of the room at all.
Compared to water heating, electrical systems are more resistant to mechanical damage - there is absolutely no possibility of water leakage and other unpleasant consequences caused by long-term operation or other physical factors.
Electric floors do not require bulky control systems
(Illustration source: www.ura-remontu.ru)
But, as you know, in every barrel of honey there is a drop of tar. Electric underfloor heating is no exception. Despite their certain advantages, they still have some disadvantages.
In some cases, the total power output that electric underfloor heating can provide may not be enough to cover the heat loss in the room. The floor must not be too hot, as this will make it much more difficult to walk on it and may lead to deformation of the floor covering. We pay attention once again - in order to avoid such incidents, it is necessary to carry out thorough thermal engineering calculations. Only correctly calculated results will help to build effective system floor heating, capable of maintaining optimally comfortable temperature conditions in the room.
Many people are interested in an essential question - does the warm floor spoil the furniture? It does not spoil something, but the heating efficiency in the case of many pieces of furniture installed without legs directly on the flooring significantly reduces the heating efficiency. In simpler terms, a wardrobe or a sofa without legs will take away the heat intended for the air in the room. To prevent such a trick, try to think over a plan for arranging furniture around the room in advance and leave these areas uninsulated. Or - give preference to furniture with high legs so that the heated air can circulate freely.
Furniture without legs significantly reduces the effectiveness of electric underfloor heating
(Illustration source: murakami.com.ua)
Another drop of tar - the choice of flooring. It is no secret that all underfloor heating systems function perfectly in the presence of ceramic or stone floors, which in themselves are excellent conductors of heat. With wood, the situation is somewhat worse. But modern manufacturers of electric floors have taken this feature into account and now your parquet or laminate flooring in the living room will warm up as efficiently as the tiles in the bathroom. But, of course, not so fast. In addition, when choosing a floor covering, you should carefully read the instructions - perhaps that particular type of flooring is not intended for installation over a floor heating system. An improperly selected coating will not only not provide you with the necessary temperature on its surface, but under its influence it can be significantly damaged. So, citizens, be vigilant when choosing materials.
Best of all, electric underfloor heating justifies itself in the company with ceramic tiles.
(Illustration source: vopros-remont.ru)
And - the last. Since the cost of electricity in our country is relatively high, you should carefully consider the feasibility of installing electric underfloor heating. Another thing is if you have no other option - then the electrical system is the only right solution. In another case, remember that the water floor heating system is much more economical from this point of view.
Platonov A. I.
Specialists of the company "TRIA Complex engineering systems» design, install, integrate and maintain underfloor heating (or underfloor heating) systems for country houses, cottages, apartments, offices and restaurants, which are located in Moscow and the Moscow region.
Our company has experience in creating water floor heating systems for facilities ranging from 240 to 2500 square meters. meters. On our website you can find an extensive list of developed objects.
It should be noted that our company approaches the creation of an underfloor heating system with great responsibility, because. we understand that a high-quality system of "warm floors" is one of the conditions for a comfortable climate in the house. It is the underfloor heating system that comes close to ideal indoor heating, because it allows you to maintain more high temperature at the feet than at head level. The surface of the "warm floor" is, in fact, a low-temperature radiator that provides comfortable horizontal heat radiation and slow convector flow.
The underfloor heating system can be used as a primary or secondary heating system. We would like to note that in our climate zone- we are talking about Moscow and the Moscow region - the floor heating system is used in combination with a radiator heating system. Only in southern areas with a warm climate can an underfloor heating system be used as the main heating system, as it allows you to compensate for all heat losses in cold weather.
Design
In our projects of underfloor heating systems, we use solutions that allow us to fully use the capabilities of the underfloor heating system.
We want to note right away that without a project for "warm floor" systems, reliable floor heating cannot be created. No need to think that a foreman with installers will come to you and quickly and correctly lay “warm floors” for you. The underfloor heating system must be designed in strict accordance with the current norms and regulations. To understand the significance of our work, below we propose to consider the list of works that our specialists perform when designing a "warm floor".
Employees of our design department choose the design of the "warm floor", the laying scheme, the thickness of the floor screed, the diameter and type of pipes for underfloor heating.
In addition, the required coolant flow rates on the "warm floor" circuits are calculated. This calculation affects the temperature of the floor and the room. Next, a hydraulic calculation is made (calculation of pressure losses) and the selection of pumping equipment.
The choice of the design of the "warm floor"
The design of the "warm floor" can be "bulk". In this case, the "warm floor" pipes are poured with concrete. Ultimately, the concrete slab becomes a heat emitting element.
Another option is a "dry" underfloor heating design. In this design, the pipes of the "warm floor" system are laid in special metal plates. In this design, they are a heat-radiating element. Then the pipes in these plates are covered with plywood or drywall, and finishing material is placed on top.
Laying and wiring diagram
When designing water "warm floor" systems, we use pipe layouts that provide the most even distribution of heat over the floor surface.
In the design of this heating system, indents from the walls are taken into account, as well as indents from the planned furniture installation sites. Those. when designing underfloor heating systems, we try to take into account the designs of designers or the plans of the customer in order to create the most efficient and reliable underfloor heating system.
In our projects, we use a collector-beam wiring scheme for “warm floors”. The location of the "warm floor" collectors is designed in such a way that the length of the pipes laid between the collectors and the underfloor heating zones is minimal. This will help balance the underfloor heating system and improve temperature control in individual rooms.
Floor screed thickness
Below is a diagram of the water "warm floor" in layers, which we use when laying floor heating using metal-plastic pipes. The thickness of such a "warm floor" can be from 70 to 110 mm. The diagram shows the thickness of each layer of the "warm floor".
The scheme of the water "warm floor" by layers
The thickness of the "warm floor" must be taken into account by builders, designers, architects, and the customer when designing premises in which it is planned to install an underfloor heating system.
Selection of pipes for underfloor heating
When designing "warm floor" systems, the diameter and material of the pipes for laying the "warm floor" are also selected. As materials for underfloor heating pipes, we use metal-plastic, polymer or copper pipes.
Examples of developed projects
IN standard project combined heating can be seen short description of the implemented project of the "warm floor" system of a private two-story residential building with an area of 300 sq. meters.
Mounting
The installation of "warm floor" systems is carried out by the installation teams of our company. This ensures maximum compliance installation work design solutions, because there is no inconsistency in the work of various subcontractors.
Our installers clearly maintain the technology and the main stages of installation work when laying the "warm floor" system.
The "warm floor" system is built according to a collector scheme using metal-plastic, polymer and copper pipes and modern shut-off and control valves.
When installing the collectors of the floor heating system, our company uses balancing fittings equipped with indicators (rotameters) of the coolant. The use of such fittings allows you to more accurately balance the floor heating system, because. according to the indicator of the passing volume of the coolant, it is clear what condition each heating line of this system is in.
At the final stage of installation work, our specialists perform hydraulic balancing of the floor heating system, start-up, adjustment and regulation of the parameters of the heating system in accordance with project documentation. In the collectors on the flow meters, the values of the coolant flow rates are set in accordance with the design documentation.
Below are two examples of underfloor heating systems that our company has installed in country houses. In the first example, metal-plastic pipes were used for the installation of an underfloor heating system, and in the second, copper pipes. All collectors of the "warm floor" are equipped with rotameters for proper balancing of the heating system.
Installation of an underfloor heating system using metal-plastic pipes
Installation of a system of copper "warm floors"
The collectors of the underfloor heating system are equipped with flow meters and thermostatic valves, which allow room-by-room regulation of the coolant temperature.
An electric “warm floor” can also be used as an underfloor heating system. It is advisable to do an electric "warm floor" in the case when it is not possible to connect to the main heat supply system, for example, this situation is possible when creating an underfloor heating system in an apartment or office, as well as in small areas in houses and cottages.
An example of installing electric "warm floors" at one of our facilities
In country houses, cottages and other facilities that have an individual boiler room, our company recommends the creation of only systems of water "heat-insulated floors".
Integration
It is possible to connect the underfloor heating system to the integrated Smart Home control system. To control the "warm floor" system, servo drives for controlling the heating circuit are installed in the collectors. The servo drives are controlled by a controller that analyzes the temperature sensors in the premises of a house or cottage, and by closing or opening the coolant supply to the heating circuit, raises or lowers the temperature of the “warm floor”. This is how a simple version of climate control is organized by heating zones.
More complex options for integrating the heating system with other climate systems and control systems are also possible to provide more advanced climate control. For example, with the help of the AMX control system, it is possible to integrate underfloor, radiator heating and cooling systems into one single-controlled climate system. Otherwise, when the heating and cooling systems work like two systems - each with its own climate control, they can run against each other at full power, like two racehorses at the finish line. That is, full-fledged climate control is unattainable in this case.
The experience of our integrators allows us to achieve the correct integration of underfloor heating with other climate systems. The AMX control system will monitor and control all climate control systems to maintain a comfortable indoor climate.
The temperature in the underfloor heating system can be controlled using user interfaces on touch control panels or, for example, on an iPad.
Service maintenance
Our service engineers provide maintenance services for the installed underfloor heating system.
On our website, you can also fill out a feedback form that allows you to make an application for
To date, the technology of underfloor heating is not much inferior in efficiency to radiator heating systems, while it has a lot of advantages. We propose to consider the main advantages of concealed heating systems, installation and connection features.
Advantages of concealed heating
One side of the attractiveness of underfloor heating systems is the concealment of utilities. Neither radiators, nor heating pipelines, nor shut-off and control valves will disturb the harmony of the interior. However, this is not the only plus of the secrecy of the heating system.
If in the living rooms the pipes do not pass through the wall ceilings and along them, this will greatly facilitate the finishing works. For leveling and application decorative materials the entire plane of the walls is accessible, in addition, there are no difficulties with cutting the floor covering, there is no need to hide the passage of pipes during installation stretch ceilings. Especially advantageous is the absence of visible communications when changing the layout.
In addition to aesthetic advantages, there are also technical ones: uniform heating of the floor creates an optimal scheme for the distribution of warm air. Since the main emphasis is not on convection heat transfer, but on its direct radiation, there is no need to warm up the upper uninhabited zone. Due to this, a reduction in heating costs of about 10-15% is provided. What is most interesting, the savings here do not come at the expense of comfort: in the leg area, the temperature is about 20-22 ºС, in the head zone - 3-4 ºС lower.
The main disadvantages of a water-heated floor
The main disadvantage of the underfloor heating system can be called the complexity of its device. The process of laying heating elements in the floor is quite technological and time-consuming, but if we are talking about a water heating system, there are additional difficulties with organizing the piping and setting up the heating operation.
This is not a reason to abandon the use of underfloor heating. When using high-quality materials and installation systems, observing the technology of laying pipes in the floor and flooring, all efforts will pay off handsomely. Underfloor heating is a really efficient, economical and durable heating system, but, again, only if it is arranged in compliance with a number of key requirements.
Of the complexities of the device, it is worth mentioning separately the need for careful selection of material for floor screed. In addition to strength qualities, it must meet the standards for heat capacity and thermal conductivity, as well as the ability to radiate heat in a certain spectrum - about 9-10 microns. In principle, when heated to 40 ºС, almost all cement-bonded materials radiate heat in this range. It remains only to achieve the highest possible coating density and uniform distribution of thermal energy in the warm layer of the screed. For this purpose, steel fiber, liquid glass or special polymer additives for underfloor heating screeds - plasticizers C-3, HLV-75, BV 3M and the like can be used.
Materials for the device
As already mentioned, underfloor heating systems require extremely careful selection of materials. A decade and a half or two decades ago, everyone was content with laying a metal-plastic pipe in the floor, convincing themselves that, apart from corrosion, nothing threatens the heat exchanger in the floor. This approach has a number of disadvantages, which are revealed during the first 3-5 years of operation.
In order not to repeat other people's mistakes, pipes should be used for underfloor heating, which, if damaged, are able to restore the polymer structure over time and have the highest thermal conductivity. It cannot be guaranteed that during the installation of the tubes they will not be broken, but for metal-plastic this is, without exaggeration, a death sentence. Cross-linked polyethylene behaves best in this regard, the alternative to which is copper. In the latter case, there are a number of additional advantages: even higher thermal conductivity, a meager coefficient of thermal expansion and the ability to remember the shape during deformation.
For open heating systems, the absence of excess pressure can lead to the ejection of gas molecules through the walls of the tubes; over time, gas particles can collect into rather large plugs. To exclude such phenomena, modern pipes for underfloor heating are made composite with a built-in oxygen barrier.
From materials for the device of a heat-insulated floor it is impossible to bypass a heater. Its choice is of decisive importance for the durability of the heating system and the floor as a whole. The thermal barrier must be incompressible, shape-retaining and, of course, with a high resistance to heat transfer. Of all the options, extruded polystyrene foam and polyurethane foam are most suitable for use as a thermal cutoff, polyisocyanurate boards are less commonly used.
Do you need a backup heating system?
You can often hear the opinion that water floor heating systems are unreliable, and therefore, when using them as the main source of heating, there is not an illusory risk that over time the house will be left without a single source of heat. This delusion is connected, first of all, with the experience of operating underfloor heating systems, which, in essence, are budget fakes of the original technology.
Judge for yourself: in the case of using low-quality pipes for a heat exchanger, the risk of clogging, breakage and destruction of the screed due to thermal expansion increases significantly. Here it really makes sense to combine floor heating with the installation of radiators, although this option heating system is associated with difficulties in setting: you constantly have to adjust the flow, otherwise the temperature in the room rises to truly uncomfortable values.
However, if the underfloor heating is arranged taking into account all technological requirements, it can work as the main heating system for many decades. Attentiveness and sensitivity at the stage of installation of thermal insulation, pipes and when pouring the screed eliminate the main risk factors for both leakage and damage to the floor covering or the base on which it is laid. In general, the costs of organizing a backup heating system and the correct installation of a water-heated floor are approximately equal.
Preferred types of boilers
The main disadvantage of water floor heating systems is their extremely low resistance to overheating. Basically, this rule applies to heat exchangers made of polyethylene - this material has one of the highest coefficients of linear thermal expansion. For copper pipes, this figure is much lower.
In connection with such limitations, the correct choice of the boiler unit and the corresponding setting of its operating mode are required. Boilers for natural gas and electricity are considered the most suitable. Their thermoregulation system makes it possible to exclude the supply of too hot coolant to the underfloor heating system.
The least suitable for connecting a water floor heating system can be safely called solid fuel boilers. Their peak power is almost impossible to limit, especially when periodically changing the type of fuel. That is why such systems require the inclusion in the hydraulic circuit of special devices that maintain the temperature of the water in the heating circuit by mixing liquid from the return.
Wiring diagram
The final argument against underfloor heating systems is the complexity of organizing a heat carrier distribution scheme. If there is more than one floor heating circuit in the system, the installation of hydraulic manifolds with flow regulators is required.
Scheme of heating a house with water warm floors. A - gas heating boiler; B - combined mixing unit and manifold group; B - the contour of the warm floor. 1 - boiler with built-in circulation pump; 2 - security group; 3 - expansion tank; 4 — three-way valve mixing; 5 - circulation pump; 6 - ball valve; 7 - needle valve or servo valve; 8 - pressure reducer; 9 - flow meter
On the one hand, the installation and commissioning of such complex networks is comparable to additional costs. However, all efforts to organize heating with underfloor heating are more than compensated by the comfort of its use: in each room you can easily adjust your own thermal regime, while the entire system can be easily and efficiently balanced even if there are several dozen “loops”.
Otherwise, the connection of a warm floor is made according to classical pattern organization of a closed heating system with excess pressure. The only addition is the water treatment unit at the make-up inlet: since the heat exchanger is represented by rather narrow channels located at the lowest point of the system, it is required to remove from the water all mechanical impurities that can settle and eventually completely clog the tubes.
With the rise in the standard of living, the requirements for comfort in our apartments have increased. Even 10-15 years ago, an ordinary consumer did not think about which heating system to choose. A proven and fairly easy-to-use water heating system was taken as a basis. Giving preference to this type of heating, it only remained to decide on the type of system to be installed (namely, one-pipe or two-pipe system, top wiring or lower, type of heating device - convector or radiator, etc.). Radiant, passive solar or floor heating systems were perceived as exotic.
Alexander KUKSA, Global 17 East
Rice. 1. Temperature distribution in a traditional heating system
Rice. 2. Temperature distribution in the room with underfloor heating
However, it would be a mistake to say that underfloor heating systems are radically new technologies for us. Back in the USSR in the 70s. there were terms for underfloor or baseboard heating. But attempts to introduce such systems, as a rule, remained only projects, embodied only in technical documentation and drawings. The main reason is the lack of quality materials with which it was possible to implement the plan.
So, for underfloor heating it was proposed to use ordinary steel pipes, and for wall heating, ready-made heating panels were developed with coils already poured into concrete. Due to the low manufacturability of the installation of the system, neither the first nor the second was effective and did not give the expected results. After all, it is almost impossible to bend steel pipes without preheating, and bulky prefabricated panels could not always be integrated into living quarters. And the standard service life of these structures, as a rule, did not exceed 20 years, and the estimated service life of the building is approaching 100 years.
The idea of using telephone cables as heating elements in electric underfloor heating led to increased values of the electromagnetic field in the room, and this adversely affected human health. Underfloor heating systems have again attracted attention with the appearance on the market of high-quality polyethylene and metal-plastic pipes for water heating, fittings and fittings for them, as well as special heating cables. In European countries, this system has long been widely used as a convenient and efficient technology.
Regulatory documents (ed. note), according to which in Russia it is possible to carry out the calculation and installation of underfloor heating systems:
1. SNiP 41-01-2003 - "Heating, ventilation and air conditioning". Adopted and put into effect on January 1, 2004 by the Decree of the Gosstroy of Russia dated June 26, 2003 No. 115 to replace SNiP 2.04.05-91.
2. SNiP 41-02-2003 - "Heat networks". Adopted and put into effect on September 1, 2003 by a resolution of the Gosstroy of Russia dated June 24, 2003
No. 110 instead of SNiP 2.04.07-86.
3. SNiP 41-03-2003 - "Thermal insulation of equipment and pipelines". Adopted and put into effect on November 1, 2003 by a resolution
Gosstroy of Russia dated June 26, 2003 No. 114 instead of SNiP 2.04.14-88.
4. SP 41-102-98 - Code of Practice "Design and installation of pipelines for heating systems using metal-polymer pipes".
Advantages and disadvantages of underfloor heating systems
There are a lot of advantages of water floor heating systems over traditional ones:
- Increased comfort. The floor becomes warm and it is pleasant to walk on it, because. heat transfer occurs from a large surface with a relatively low temperature.
- Uniform heating of the entire area of \u200b\u200bthe room, and therefore uniform heating. A person feels equally comfortable near the window and in the middle of the room.
- Optimal temperature distribution along the height of the room. The saying has long been known: "Keep your feet warm and your head cold."
hygiene. There is no air circulation, drafts are reduced, and therefore there is no dust circulation, which is a big plus for people's well-being, especially if they suffer from respiratory diseases. A significant part of the heat from the floor is transferred in the form of radiant heat transfer. Radiation, unlike convection, immediately spreads heat to surrounding surfaces.
There is no artificial dehumidification of air near heating devices.
Aesthetics. There are no heating devices, there is no need for their design or selection optimal sizes. Economic benefit. By switching off the heating circuits in the floor or reducing the flow of water through them, it is possible to regulate the temperature in those areas or rooms where it is necessary. For heating, water with a temperature of 40-50 °C is used. This makes it possible to widely use secondary energy resources, as well as heat pump installations as a source of heat. The system of water underfloor heating, like any other technology, has its drawbacks:
- The specific heat loss of the room should not be more than 100 W / m 2 of the floor. Otherwise, the room requires additional thermal insulation or the use of a combined system: radiators and underfloor heating.
- Also this species heating cannot be used in multi-storey residential buildings with single pipe systems central heating. It is not uncommon for residents to arbitrarily install underfloor heating in bathrooms and toilets. In this case, the heating circuit is connected to the inlet of the towel dryer. This leads to the fact that the floor temperature in these rooms often reaches 45 ° C and above. As a result, a person cannot physically step on such a floor without shoes, and all the advantages of this heating method are lost. In addition, the water, having passed through the heating circuit, is cooled, and the neighbors in the riser receive hot water at a temperature lower than necessary.
- The need to fill the floor cement mortar, as well as additional insulation, leads to a rise in the floor level from 10 cm (on the second floor and above) to 13-15 cm on the first floor and in the case of a cold basement. This, in turn, leads to additional work for door installation. Also, a large thickness of the fill leads to an increase in the load on the floor slabs and load-bearing structures.
- The cost of installation and materials is higher compared to traditional heating.
Rice. 3. Underfloor heating structure in cross section (1 - wall, 2 - plinth, 3 - damper plate, 4 - tire for laying pipes, 5 - metal-plastic or polyethylene pipe, 6 - floor covering, parquet, linoleum, tiles, etc. ., 7 - concrete screed, 8 - polyethylene film 80-100 microns, 9 - thermal insulation layer, 10 - sound insulation layer, 11 - floor slab)
Physics of the process of heat transfer from the floor surface
For every degree difference between the temperature of the floor and the air in the room, there is about 6.5 W / m 2 specific heat, carried by convection, and about 5 W / m 2 specific heat in the form of thermal radiation. Convection heat is distributed throughout the room by the movement of air currents. Thermal radiation is transmitted directly to surrounding objects, furniture and people in the room. The formula illustrating heat transfer during thermal radiation looks like this:
where t p - average floor surface temperature, °C; t to - air temperature in the room; °C.
The following formula illustrates heat transfer during convection:
a conv \u003d 4.1 (t p - t k) 0.25, W / (m 2 x °С
The total specific heat flux from 1 m 2 of the floor surface:
q \u003d 4.1 (a izl + a conv) (t p - t to ), W / (m 2
In total, the heat output per degree difference between the average floor surface temperature and the air temperature in the room is 11.5 W/m2. In well-insulated modern houses in the coldest season, the heating load is 50-60 W / m 2. In other words, to maintain the temperature in the room at 20 ° C with a heating load on the floor of 50-60 W / m 2, the temperature of the floor surface should be 4.5 and 5.5 ° C, respectively, higher than the air temperature in the room.
The device of the underfloor heating system
The underfloor heating system generally consists of several layers and is arranged according to the "layer cake" principle.
Installation of a warm floor
On the cleaned and dry surface of the floor slab 1 (hereinafter, see Fig. 3), sound-10 and heat insulation 9 are laid (the concrete slab is considered dry when it reaches relative humidity 80%). Irregularities in the floor must first be leveled with a cement screed. Laying a polyethylene film under the insulator plates is required if an unheated room, a room with high humidity or outside air is located below. It is possible to use one type of insulator, because thermal insulation also performs the function of sound insulation. Typically, the total insulation thickness is 40 mm. As insulation, polystyrene boards with a density of at least 35 mg/m3 can be used, other insulating materials with a thermal conductivity coefficient from 0.028 W/(m-°C) to 0.05 W/(m-°C) are also suitable. For example, you can use foam boards, rigid and semi-rigid mineral boards Rockwool, Paroc - 0.04 W / (m - ° С), etc. The thickness of the insulating layer depends on the air temperature in the room below, and is taken at initial stage calculation. It can be from 20 mm, in the case of a heated room below with an air temperature of about 20 ° C - up to 80 mm, if there is cold outside air from below the plate. The damper tape 2 can be a foam tape or a polyethylene foam tape with a thickness of 5-10 mm. It is necessary to compensate for the thermal expansion of the concrete screed. After the screed has hardened and the floor finish has been laid, the protruding part of the tape can be cut off and the gap hidden with a plinth. At the same time, the plinth is attached to the wall, and not to the floor covering.
Rice. 4. Thermal insulation board Oventrop NP-35
Rice. 5. Laying with metal mesh
Rice. 6. Laying with metal mesh and wire
A polyethylene film is laid on top of the insulation, it should also cover the damper tape. Glue all the joints of the layers of the film with adhesive tape. The film acts as a waterproofing, preventing moisture from the poured concrete screed from impregnating the thermal insulation layer. Fastening pipes to the floor with the required pitch can be done in several ways. You can use special ready-made slabs insulator with ledges, e.g. Oventrop NP plates -35 (see Fig. 4). These plates allow you to quickly lay the pipe with the required pitch. Pipe laying using special plastic tires 4 is more appropriate. They have a number of recesses with a pitch of usually 50 mm, in which the pipe is firmly snapped into place. Typically, these tires require three to four per room (every 2-3 m along the bus). Such tires are fastened with double-sided tape to a plastic film; for reinforcement, you can also nail them with plastic staples (see Fig. 7) using a special tool. Pipes are also recommended to be fixed with these brackets every 1-1.5 m of length, and especially carefully at bends, because. it is at the bends that the pipes can be lifted due to the stresses that arise during the bending of the pipes. Quite often, pipes are laid on large-mesh metal meshes, with a typical cell size of 150 mm by 150 mm (see Fig. 5, 6). Then the pipes are tied to the grid with wire or nailed with plastic staples to the insulator plates. There is a grid laying on top of the heating pipes. The mesh acts as a heat conductor and allows for a more even distribution of heat from the pipes in the horizontal plane of the screed. The grid can also be installed on top of mounted and fixed pipes in order to evenly distribute heat, but with a pipe spacing of 10-30 cm this is not very necessary. On the supply pipelines (both supply and return), ring insulation is put on, made in the form of a sleeve. The supply pipelines are isolated in places where they are densely located, these are usually utility rooms and corridors. The length of the insulating sleeve should not exceed 6 m. The distance from the pipe to the walls is usually 10 cm, this applies to both outdoor and indoor interior walls. Concrete is poured after the pipes are installed, the installed system is filled with coolant and hydraulic tests are carried out. The thickness of the screed over the pipe must be at least 45-50 mm. Concrete grade - not lower than M-300 (B-22.5). After installing the system, it is very important to make hydraulic equalization of the circuits. For hydraulic balancing of each circuit, valves are located on the return manifold. Each circuit has its own head loss. The circuit with the greatest pressure loss is selected for the main one, an open valve is left on it, the remaining circuits are equalized by the difference between the maximum pressure drop and the difference between the circuits themselves. For these purposes, there are special schedules that are provided by the manufacturer for each type of valve. The calculation of the positions of the control valves is carried out at the final design stage. The market offers a wide range of pipes, fittings and related materials for installing underfloor heating. The durability of the system and its reliability will primarily depend on the type of pipes chosen. Many companies offer only polyethylene pipes, claiming that only these pipes are ideal for installing underfloor heating. But it's not. Abroad, where such systems have already become widespread, metal-plastic pipes are mainly used. It has an aluminum oxygen-tight layer and is very easy to install. When bent, it does not return to its original position, like polyethylene, thus, fewer fixing brackets are needed at pipe bends. The aluminum layer reliably protects against oxygen diffusion inside the pipe, while increasing the heat-conducting capacity of the pipe wall. But during installation, it is necessary to observe the values of the minimum bending radii, they are about five diameters. These values can vary greatly from manufacturer to manufacturer. Therefore, if possible, you need to choose pipes with the smallest bending radius, and they are, accordingly, more expensive. Also, the closest attention should be paid to the aluminum layer. In no case should you use pipes in which this layer overlaps, when bending to a small radius, it will almost certainly diverge, and there will be little sense from such a pipe, and the likelihood of leakage at the bend is very high. It is very expensive to dismantle a concrete screed at the place of a leak, and it is not recommended to connect pipes in a screed. So, the choice of pipe type depends on the availability of high-quality metal-plastic pipes on the market. Otherwise, it's better to choose polyethylene pipe The choice of pipe size depends on the heat load per linear meter of the pipe, the coolant flow rate and is determined at the initial design stage. The most common pipes are 16/12 mm (inner diameter 12 mm). In rare cases, pipes of other sizes are used: 20/16 and 18/14mm. Having received an application for designing a warm floor, you need to evaluate the design object itself. A visit and inspection of the site is desirable, but if there are ready-made floor plans and sections with dimensions made to an acceptable scale, this need is no longer necessary. Design should begin immediately after receiving the plans from the architect. It may be necessary to change the location of the shafts in the house, the material, the thickness of the insulation, the thickness of the bearing walls and ceilings, and to determine in advance the locations of the technological holes for the risers. The initial data for design are: The following questions should also be discussed with the customer: Supply water temperature. The supply temperature can be between 40 and 50 °C. If a heat pump installation is used as a heat source, it is advisable to take the temperature of the supply water to the underfloor heating circuit as 40 °C. In all other cases, any supply temperature within the above limits can be used. Loss of pressure. The pressure loss in the underfloor heating circuit must not exceed 15 kPa, best option 12 kPa. If the circuit has a head loss of more than 15 kPa, it is necessary to reduce the coolant flow or divide the floor area in the room into several circuits. material of external walls (listing from the internal layer): interior wall material: Brick 0.44 W/(m-°C); Calculation of heat transfer coefficients of external fences. The calculation is made according to the standard formula: Calculation of heat loss of premises. Calculation of heat losses in rooms is carried out according to the SIA 384/2 method, i.e. the heat loss of a room is the sum of the losses through all the fences of a given room. Heat losses due to infiltration of outside air through leaks are also calculated. We will not focus on these calculations, because any design engineer owns them to a sufficient extent. The calculation results are summarized in Table. 2. The author of the article uses the WinHT software product of the Swiss company AAA Software fur den Haustechniker, which specializes in programs for designers. This program allows you to make the whole range of thermal calculations. 
Rice. 7. Plastic pipe clamp
General recommendations when designing underfloor heating
Temperature drop. coolant in the circuit. The optimum temperature difference at the inlet and outlet of the underfloor heating circuit is 10°C. That is, the temperature regime is 40/30.45/35, 50/40. Unfortunately, this is often impossible to achieve, and therefore the recommended drop is in the range of 5 to 15 CC. It is not recommended to install less than 5 CC due to the greatly increasing coolant flow through the circuit, which leads to large pressure losses. It is not recommended to take more than 15 ° C due to a noticeable difference in the temperature of the floor surface, i.e. under the windows we can have a floor temperature of 27 °C, and at the end of the circuit it drops to 22 °C.
Outline length. The maximum length of one circuit should not exceed 120 m, the optimal length of the circuit is 100 m. If two or more circuits are laid in the room, their length, if possible, should be designed the same. If the area of the room is very small and the heat loss from it is small ( toilet room, area before entrance doors), you can combine contours, i.e. heat it from the return pipe of the adjacent circuit.
Pipe pitch. The following distances between pipes are used: 10/15/20/25/30 cm. In exceptional cases, inter-pipe distances of 35/40/45 cm are used, for example, for heating halls, gyms.
Heat supply to the room. Heat influx can be from operating equipment, household appliances etc. Heat inflow into the room through the ceiling is taken into account if the room above has the same underfloor heating. The calculation of multi-storey buildings must be carried out with top floor to the bottom. For example, losses through the floor in a room located on the second floor are a useful heat gain for a room located on the first floor. At the same time, the useful heat gain of the premises on the first floor is taken to be no more than 50% of the losses of the premises on the second.
Maximum floor surface temperature:
Minimum coolant flow through the circuit. When designing underfloor heating, it must be remembered that the minimum coolant flow rate for each circuit can be set on the control valve at least 27-30 l / h. Otherwise, you need to merge the contours.
Calculation example
On fig. 8 shows a plan of a two-room apartment on the second floor, which, at the request of the customer, is heated by the "warm floor" system. Geographically, the apartment is located in Switzerland, the project was approved in December 2004. The temperature in the rooms was chosen by the customer.
Initial data for calculation:
wall against staircase(heated, temperature 15°C) insulated from the side of the staircase mineral wool 30 mm thick.
where a nar is the heat transfer coefficient from the outside air, equal to 20 W / (m 2 - ° С); аВн - heat transfer coefficient from the side of internal air, equal to 8 W / (m 2 - ° С); 5 - material layer thickness, m; X - coefficient of thermal conductivity of the material, W/(m-°C). The values of the heat transfer coefficients are taken from the Swiss code SIA 384/2 (Schweizerischer Ingenieurund Architekten - Verband, Warmeleistungsbedarf von Gebauden). The following values were obtained from the calculation (see Table 1).
Underfloor heating calculation. Consider an example of calculating room 03 (see Fig. 8). For a better understanding, we will make the calculation according to the method of manual calculation of the floor heating system from NAKA AG. The calculation is quite laborious, and this makes it practically inapplicable for calculating a large number of rooms, for example, when designing heating for apartment buildings. In addition, it does not have a sufficient degree of accuracy in determining the actual flow rate of the coolant through the circuit and the return water temperature and can be used for a preliminary assessment of the consumption of materials during the installation of an underfloor heating system.
Table 1. Estimated heat transfer coefficients
Specific heat loss:
where Q h is the heat loss of the room, excluding losses through the floor, W; A - area suitable for laying pipes, m 2.
Thermal resistance of the coating. Parquet, depending on the thickness and material, has a thermal resistance coefficient R = 0.07-0.1 (m 2 x ° C) / W, carpet - about 0.14 (m 2 x ° C) / W, marble slabs - 0.01-0.02 (m 2 x ° C) / W.
coolant temperatures. The supply temperature of the heat carrier is 45 °C, the return temperature is 35 °C.
Average coolant temperature: 
Area of the edge zone. The so-called edge zones are laid under the windows. The pipe is laid in them with a small step, usually 10 cm, the depth of such a zone depends on the size of the window and the ratio of the window area to the area of the entire wall.
Usually take from four to eight turns of pipe in the edge zone. Windows in room 03 occupy less than 25% of the total wall area, while the edge zone has four turns in 10 cm increments. The depth of the zone is 50 cm.
A R \u003d 0.5x2.2 + 0.5x3.8 \u003d 3 m 2
Table 2. Heat loss of premises
Specific heat flux in the edge zone. According to the pipe pitch in the edge zone of 10 cm, the temperature difference of 20 °C, with a fixed value of the thermal resistance of the coating of 0.14 (m 2 - °C) / W, we obtain from the diagram in fig. nine: total heat, distinguished in the edge zone:
q R \u003d 67 W / m 2
Residual heat:
Q A \u003d 630-201-0 \u003d 429 W.
Thus, it remains to cover at least 430 watts in this room.
The area of the inner zone. The area is equal to the difference between with total area premises and the area of the edge zone.
Minimum required heat flux of the inner zone:
Let's use Fig. 9. The specific heat flux obtained as a result of the calculation q A \u003d 27.2 W / m 2 more than the minimum possible. So, from the diagram it can be seen that at a temperature difference of 20 ° C, even with a pipe pitch of 40 cm, a heat flux of 36 W / m 2 is provided. The recommended maximum pipe pitch for residential premises is 30 cm, we accept it.< При этом эффективный удельный тепловой поток внутренней зоны составляет:
q A eff \u003d 43 W / m 2
Effective heat dissipation of the inner zone:
Q A eff \u003d 43 x15.8 \u003d 680 W.
Heat loss through insulation to the room below. On the first floor there is the same two-room apartment. The air temperature of the lower room is 20 °C. Temperature difference between the coolant and the air temperature in the lower room:
Δt in.in \u003d t in.av - t to \u003d 40-20 \u003d 20 ° С.
Rice. 9. Specific heat flux, carpeted
According to the diagram in fig. 10 we find the losses through the insulation in the lower room. In the edge zone, with a pipe pitch of 10 cm:
q D
In the inner zone, with a pipe pitch of 30 cm.
q D ext \u003d 11.5 W / m 2.
Correction for insulation thickness other than 20 mm:
40 mm - f = 0.64;
50 mm - f = 0.54.
Thermal resistance of heat output of two layers of insulation in room 03:
Equivalent insulation thickness with value λ:
δ
Correction f = 0.64, total:
q D
q D ext 11.5 x 0.64=7.4 W/m2
The heat loss through the floor insulation will be:
Q D = q D
Coolant flow rate per circuit:
The length of the supply pipes from the measurements according to the drawing is 22 m. Total pipe length:
L \u003d 83 + 22 \u003d 105 m.
Loss of pressure. From the diagram in fig. 11 according to the coolant flow rate m = 89.2 kg / h and the selected pipe 16/12 we find the specific head loss:
Δh =74Pa/m.
Total head loss:
ΔH = ΔhL =74 x 105=7770 Pa.
Each room is calculated in the same way. After the calculation, drawings are made. A table is provided for each room and is used when installing the system (see fig. 12)
The efficiency of an underfloor heating system primarily depends on the competence of the designer. The calculation of underfloor heating is a very time-consuming process, it also includes the calculation of heat losses in rooms. Without a proven calculation methodology or a specialized software product, it is almost impossible to correctly calculate the entire system. A system calculated "by eye" by craftsmen, and besides, not hydraulically equalized, will only be the subject of constant customer dissatisfaction and will not provide the required level of comfort. In itself, floor heating is a rather expensive system, because you need to purchase expensive and high-quality pipes, thermal insulation, fittings, combs, control equipment, circulation pumps.: Therefore, the price of a design error turns into a round sum. But it is almost impossible to correct shortcomings and miscalculations in the installed and flooded floor heating system, even in a single room. This is comparable to the installation new system plus the cost of dismantling the old one.
Now many individuals are engaged in the installation of underfloor heating. At the same time, as a rule, they use typical operating time, while each project has a lot of individual features that need to be taken into account at the initial design stage, and not try to adjust with a hammer standard system, which for some reason does not want to work as it should. The installer performs his work according to the drawing and is only responsible for the quality of the installation, while the designer is responsible for whether the system will work correctly.
The traditional and most commonly used is water heating.
What do you associate the word "comfort" with? Surely, the vast majority with heat. Especially in a country with a cold climate, snowy winters and severe frosts. Therefore, the main system, important not only for comfortable life but also for survival is definitely the heating system. Of its many options, water heating, in which water plays the role of a coolant, is most widely used.
Features of water heating
For a long time, attempts have been made to solve the problem of heat transfer from the source to the heated premises. But the use of special channels with air as a heat carrier for this led to large heat losses.
Steam heating appeared in the middle of the 19th century. And soon he was replaced by water. The use of water in heating systems made it possible to reduce the temperature of the coolant compared to steam systems. Therefore, heating has become much safer, and heating costs are lower.
With the advent of new heat-insulating materials and technologies, it has become possible to transfer heat over long distances. Thus, centralized heating systems for quarters, districts and entire cities were built.
The water in them is heated in large heaters, after which it is transferred to the houses through external pipelines. But it is impossible to completely eliminate heat loss in such complexes, so autonomous systems have recently become popular.
The centralized system has another drawback. It does not allow to make a water heated floor from central heating. This is due to technological difficulties and administrative prohibitions. So this option is possible only due to electric heating systems. With central heating, everything is clear. What is an autonomous system?
The two-pipe water heating system is the most common
The main feature of such systems is the absence of external communications for heat transfer and, accordingly, the absence of its losses. An autonomous heater is installed in the house, and fuel is delivered by transport or transferred to the house through special highways. The optimal fuel for such systems is natural gas. In addition to it, you can use fuel oil, coal, wood and products of its processing.
To ensure the smooth operation of such systems, water and electricity must be supplied to the house. Internal communications of premises with independent heating are no different from those connected to central heating- the same pipes and the same batteries. Losses in autonomous heating complexes are minimized and depend to a greater extent on the heating equipment and the type of fuel.
Composition of the heating complex, equipment and materials
Any heating system includes:
- heater
- heat transfer lines
- heating appliances
Let's consider this scheme in more detail. And for example, let's take a complex based on a gas heating boiler. It uses natural gas from the conventional gas supply system as fuel. The gas boiler heats water up to certain temperature, after which this water is transferred through pipes to heating devices - radiators (batteries).
Battery and pipe installation
Along with traditional iron pipes, plastic pipes have also become widely used. Due to this, the installation of pipelines has become easier and cheaper, and their durability in a humid environment is much higher.
The efficiency of heating in such a system directly depends on the heating devices and the way they are installed. And along with traditional batteries, water floor heating is increasingly being used.
Let's take a closer look at this method of heating a room.
How is underfloor heating done?
Disputes about the advantages and disadvantages of such heating have not stopped since its inception. But one thing is undeniable - underfloor water heating - underfloor heating - can create a comfortable and cozy atmosphere anywhere in the room. After all, the farther from the battery, the cooler. And if a person's feet are warm, then he feels much more comfortable.
And further. How does a radiator heat a room? due to air convection. A cold stream passes through the battery and already warm rises up in a narrow strip - usually along a wall or window. So it turns out that the warmest zone is above the battery. And when the floor is heated, it is constantly under your feet.
Floor heating
When installing a floor heating system, radiators, heat exchangers and other special devices are not needed. The role of the radiator is played by pipes for water heating, laid in the floor. They can be metal or metal-plastic. The main thing is that they have good heat transfer.
Polypropylene pipes are not suitable for such systems, because they have low heat transfer, poorly transfer heat to surrounding objects and therefore cannot heat the floor material.
Heating pipes are connected to the general heating system as an independent circuit with an inlet, outlet and control valve. Thus, a warm floor from heating, or rather, its operation can be regulated independently of other elements of the system.
Choice of heating zones
When installing a warm floor, it does not make sense to heat the surface under furniture, a fireplace, a built-in wardrobe and other furnishings. After all, the owners will not go there.
Therefore, it is more logical and economical to install heating only in places of constant or frequent presence of people:
- For the kitchen, this is almost the entire area, with the exception of the space under the furniture and household appliances.
- For the bathroom - approaches to the bath and shower, and the rest - at will.
- For residential premises, everything is very individual, but the area around chairs, beds and tables should be heated.
Choice of heating zones
Do not lay water floor heating close to walls and doorways.
And one more limitation. No need to try to warm up a wooden or parquet floor. Heating is not effective on them, and the parquet can also dry out.
Pipe laying
Having determined the heating zones, you can get to work. Consider it on the example of metal-plastic pipes. They are supplied in coils of 100 meters, which allows you to lay the pipe without unnecessary joining elements. For our purposes, we need pipes with an outer diameter of 16 mm.
First, heat-reflecting screens are laid on the rough screed, and pipes are directly on them. Pipe laying in each area is done in a zigzag with parallel lines or a spiral of parallel lines. It is desirable to reduce the entrances and exits of all sections to one point - it will be easier to subsequently connect them to a common system.
If the house has a basement and it is not heated, then before laying the heat-reflecting screens, it is necessary to lay a layer of heat-insulating material over the entire area of \u200b\u200bthe room, regardless of the heating zone. After installing the pipes, you can proceed to the final screed and flooring. In this case, the thickness of the screed should not exceed 100 mm.
Such a scheme does not exclude the use of classic radiators. Wall or floor water heating radiators are connected to a separate circuit. This allows more efficient use of the entire heating complex, depending on the conditions or wishes of the owners.
Scheme for connecting a solid fuel heating boiler
All individual highways start and end in the same place. It is here that it is worth equipping a certain control point. It can be located under the stairs, in the pantry or not far from the boiler itself.
The ends of the underfloor heating pipes assembled in one place are connected to a common system. For ease of adjustment and control, it will not be superfluous to immediately install a temperature and pressure meter, control valves, and, if necessary, a booster pump. Such an intermediate control panel is especially convenient in private houses with two or more floors.
Some Conclusions
When deciding on the choice of a heating system for a house or apartment, remember that water heating in the floor cannot be tied to central heating. In this case, only electric heating can be used.
Floor heating can be connected to any heating boiler that uses water as a heat carrier. Electric and solid fuel boilers are no exception.
Floor heating can be connected to any heating boiler
If you want to heat a small area of the apartment, for example, only a section of the floor in the bathroom, it is also better to install electric rather than water heating.
Copper pipes are considered the most efficient pipes for heating in the floor - because of their good heat dissipation. But the peculiarities of welding and the high cost of the metal itself do not allow their use everywhere. Metal-plastic and polyethylene pipes have proven themselves well for these purposes.
The most effective water floor heating will be where it lies ceramic tile, linoleum or carpet.
Wooden, parquet, and laminate flooring have low thermal conductivity, so their heating is ineffective.
