High temperature heating. What is low temperature heating. Advantages and disadvantages of low-temperature heating in a private house

Low-temperature heating of buildings by design consists of low-temperature wall and floor heating. Modern wall heating looks like this: pipes through which the supply is carried out warm water from the bottom, and the one that comes out from above, then it is laid towards the wall, in most cases, parallel to the floor line. After this, the pipes are fixed using special clamps, and they are also sealed with a special plaster made from chalk and cement.

In accordance with established standards, pipes should be located at a distance of 10 millimeters from the wall surface - this can facilitate rapid heating of the premises. The main rule for installing wall heating is that in order to heat the room as efficiently as possible, you need to install pipes on about a third of the wall area. For example, if the area of the walls of a room is 30 square meters, then to heat such a room, pipes will need to be laid on an area equal to 10 square meters of walls.

Low temperature underfloor heating works in exactly the same way as wall heating. However, the floor-mounted option is known to be quite simple to install and, as a result, more affordable. Underfloor heating is particularly effective when used in damp rooms or hallways - in principle, any room with a stone or tile floor. Floor heating, when compared with wall heating, operates much more slowly and, accordingly, takes longer to warm up the room.

The main difference between low-temperature heating systems and standard models is that in an ordinary radiator the water temperature is about 70 degrees or more, and in low-temperature systems the water is heated to 30-35 degrees. Thus, heated water flows through pipes or through plastic hoses installed in the floor or wall.
The advantages of low-temperature heating of buildings include the fact that energy costs when using low-temperature systems are significantly lower than when traditional method heating. At the same time, preheating water to 20-25 degrees can be done using a solar radiator mounted on the roof.
Also, the advantages of the system include the fact that low-temperature heating installed in partitions is more economical, for the reason that there is no need to insulate pipes to prevent heat loss - it is known that they are mounted directly into the walls, which, in fact, do heating the room. Consequently, there is no heat loss as such. It is known that plastic pipes are not affected by oxygen and can be used for a long time without the risk of deposits and damage. It should be especially noted that in a room with an installed wall or underfloor heating The circulation of existing dust is significantly reduced. For this reason, it makes sense for people sensitive to dust to prefer low-temperature heating systems.

It should also be taken into account that the water itself does not heat the air, but the surfaces of the walls, creating, even in conditions of the same room temperature, a special feeling that the room with a low-temperature heating system is much warmer. Also, in such a room it is always possible to install standard heating.

Added: 04/28/2018 16:39:05

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Low temperature systems: heating of the future

The most important task of technology development is to increase energy efficiency. To solve this problem in heating systems, the most effective way is to reduce the temperature of the coolant. That is why low-temperature heating is today a key trend in the development of modern heating technology.

During operation, a low-temperature heating system consumes much less coolant compared to a traditional system. This results in significant savings. An additional advantage is the reduction of harmful emissions into the atmosphere. In addition, working with a “soft” temperature regime allows you to use alternative views equipment - heat pumps or condensing boilers.

The main problem in the development of low-temperature heating for a long time remained that at low heating temperatures it was very difficult to create comfortable conditions in heated rooms. However, with the development of construction technologies that allow the construction of energy-efficient buildings, this problem has been solved. The use of modern building and thermal insulation materials makes it possible to significantly reduce heat losses in buildings. Thanks to this, a low-temperature heating system can heat the house efficiently and effectively. The achieved effect of saving coolant significantly exceeds the additional costs that have to be incurred for thermal insulation of buildings.

Application of radiators

Initially, only so-called panel heating systems were considered as low-temperature ones, the most common representatives of which are underfloor heating systems. They are characterized by a significant heat exchange surface, which makes it possible to provide high-quality heating at low coolant temperatures.

Today, the development of production technologies has made it possible to use radiators for low-temperature heating. At the same time, batteries must meet increased energy efficiency requirements:

high thermal conductivity of metal;
significant heat exchange surface area;
maximum convective component.

Yes, application aluminum radiators Ogint Delta Plus model when creating low-temperature systems gives important advantage compared to heated floors. Optimal savings and comfort are achieved in cases where the heating system quickly responds to changes in outside temperature (when it increases, the coolant temperature decreases, and when it decreases, it increases). Modern automation used on boiler equipment provides all the possibilities for this. The disadvantage of heated floors is their inertia. Radiator systems are able to respond to changes in external conditions almost instantly.

Advantages and disadvantages of low temperature heating systems

Low temperature systems have a range of significant advantages:

significant cost savings by reducing energy consumption;
reducing the volume of harmful emissions into the atmosphere;
improvement of comfort indicators. Due to the low heating of the radiators, the air in the room does not dry out and strong convective currents do not arise that raise dust;
safety. You cannot get burned on a radiator with a temperature of +50...+60 °C, which cannot be said about a battery heated to +80 °C;
reducing the load on the boiler, which increases the operational life of the equipment;
the possibility of using heat pumps, condensing boilers and other types of alternative equipment with low temperature conditions.

The disadvantages of heating systems of this type are relative. So, a certain disadvantage is the increased requirements for the radiators used. However, the use of Ogint Delta Plus batteries completely solves all the problems of choosing heating devices.

It should also be noted that in severe frosts, low-temperature systems cannot always cope with heating buildings. At the same time, the system can be switched to operate at a higher temperature without any problems if necessary.

Radiators for low temperature heating systems

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Any heating system in a house is designed to provide its residents with comfortable living conditions in its premises.

What is a low temperature heating system?

This is a heating system where the temperature ratio of the output and input flows of the coolant fluid is equal to the ratio of its temperatures - 60/40 ° C. Of course, this distinction is rather arbitrary, and that’s not the only point here.

If we look at the root of the “temperature” issue, then from the current practice of operation of conventional heating systems, we can say that during the transitional heating period in every house or apartment with individual heating, we actually use a heating system operating mode close to this.

During this heating period, on the regulator gas boiler our heating system, we, as a rule, set the operating temperature values of 60/50 °C.

If we talk from the standpoint of comfort in the room and safe operation of the system with different temperatures of heating radiators, then it is clear that warm radiator, with a temperature of 60 °C, a low-temperature heating system at home is much more comfortable, and most importantly, safer than the radiator of a conventional heating system with its temperature of approximately 80 °C.

Also, a type of low-temperature heating system widely known among the population is the “warm floor” heating system, but this system also uses heating radiators quite effectively and often. Now let's talk about the operating temperature conditions of all modern heating systems, as well as the advantages of low-temperature heating systems.

A little about temperature conditions and low-temperature heating.

Any given temperature mode of system operation has three parameters:

Temperature of the coolant fluid leaving the boiler.

Temperature of the coolant fluid at the inlet to the boiler.

Room air temperature.

It is in this sequence that the numbers are entered in all accompanying documents for boilers.

In our “traditional” heating systems, their calculation based on temperature parameters is done in such a way that at the outlet of the boiler, the temperature should be in the range of +70 - +80 °C, and at the inlet - about +60 °C.

Approximately the same standard exists for heating systems in Europe, where, according to the standards of the EN-442 standard, the optimal parameters for heating systems are laid down in the output/input ratio of 75/65 ° C. The same standard also contains such a concept as a “soft body”, which corresponds to the temperature regime in a low-temperature heating system with an output temperature after the boiler of +55 °C and its input temperature of approximately +45 °C.

Therefore, for the calculations of modern low-temperature heating systems, it would still be preferable to adhere to European standardization standards, since it is precisely these standards that most imported boilers are adjusted to.

Yes, in principle, according to experts, soft temperature heating according to the European standard EN-442 is the future of everyone existing systems heating.

About the main advantages of low-temperature heating.

Regarding the advantages of this heating system, they are as follows:

The main advantage of a low-temperature heating system is its comfort, because the opinion that highly heated radiators of a conventional heating system significantly dehumidifies the air in the room has already become a “talk of the town”, as well as a large amount of dust in the room resulting from the movement of layers of air ( convection) with such heating.

It is difficult to evaluate all these prejudices, but one thing must be recognized is that, after all, a warm radiator in a low-temperature heating system at home is much more comfortable and preferable than its hot counterpart in a conventional heating system.

Experts say that the closer the temperature of a radiator or other heating device in a room is to the temperature required in a given room, the more cozy and comfortable it is for a person to be here.

A heating system using low-temperature technologies also provides for the possibility of using high temperatures in the premises of the house. For example, during quite severe, our “Siberian” frosts, this is acceptable.

The possibility of accumulating (accumulating) energy in a low-temperature heating system due to the use of heat accumulators in it, because the lower the temperature of the coolant fluid circulating in the heating system, the more thermal energy is “set aside” in reserve.

Ease of regulating low-temperature heating systems through the use of programmable thermostats, since the temperature spread between the heat-generating device of the system and the room temperature is significantly lower than with a conventional heating system.

Conclusion.

To briefly summarize our conversation, we can say that the low-temperature home heating system is more advanced, safe and cost-effective than the use of conventional, high-temperature heating systems in heating our homes. Therefore, low-temperature heating is the future!

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28 Design of ventilation systems with heat recovery

Ventilation with heat recovery is a system with a process of returning heat back. In our case, heat recovery means the process of heating the air leaving the room warm air cold incoming air that enters the house to ventilate and ventilate it. In other words, we return to the house the heat that we collect from all areas of the house. Before we throw out the stale air from the house, we pass it through a recuperator, where we take the heat we need from this air, and then heat the incoming cold air with this heat to a certain value. This process contains a brilliant idea - why use additional energy to heat the air at home, which is very expensive and costs money, if it can be obtained absolutely free.

There are two types of recuperators: plate and rotary.

Planar. IN this option The air leaving the room heats the heat exchanger plates, gives off its heat to them and is removed to the street cold. Incoming Fresh air takes heat from the heat exchanger plates, is heated and delivered to the premises already heated. The efficiency of a plate recuperator is up to 60%, depending on the installation. The key features of the design are simplicity and low cost, while the flows of incoming and outgoing air do not mix, which ensures that such an installation is 100% environmentally friendly.

Rotary. In the second option, the basis of the installation is an aluminum drum, which takes heat from the outgoing air and transfers it to the incoming air. The rotary recuperator has a higher efficiency, its energy efficiency reaches 80%. Unlike the plate version, it does not need to remove moisture, which collects in the form of condensation; in this version, the required amount is delivered to humidify the necessary rooms, which becomes especially important in the dry winter period. Includes both options ventilation units includes air filters, humidity and exhaust gas sensors, plus system control panels.

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The operation of any type of heating system is aimed at creating an optimal temperature regime for the residents of the house. The existing stereotype regarding “correct” heating implies a simple criterion for determining its quality - the hotter it is heating devices, all the better. But is it? Does high-temperature heating really provide the greatest possible comfort and have no negative effects on the human body?

Climate, medical and technological research has proven that this is not the case. The most desirable and safe option for creating comfortable indoor microclimate parameters is low-temperature RѕS‚РѕРїР»РµРЅРјРµ РІ С‡Р°СЃС‚РЅРѕРј РґРѕРјРµ, which is not only effective, economical and practical, but also has a positive effect on a person’s physical condition.

Key Features of Low Temperature Heating

It is important to know that the phrase “low temperatures” is quite arbitrary and is a comparative value in relation to a classic heat source with a high temperature working environment (+70-80C). Low-temperature heating of a private house works with a coolant heated to +40-45/55-60°C, where lower temperature values indicate the state of the working environment at the entrance to the heat generator, and higher temperatures at the exit. In Europe, they took a more creative and precise approach to the definition of low-temperature heating, introducing the concept of “soft heat” (EN422 standard).

Types of low-temperature heating of a private house

Heating systems with a reduced temperature of the working environment can be created on the principles of convective or radiant heat transfer:

radiator heating;
surface heating.

Radiator low-temperature heating in a private house

A variety of heating devices are used, among which panel-type radiators with bottom or side connections have proven themselves to be the best. Radiator low-temperature heating in a private house is designed to general principles, but at the same time requires careful selection of heaters with increased power due to the non-standard temperature of the coolant.

Surface low temperature heating

A striking and well-known example of the use of low-temperature heating in a private home is the system "warm floors". The pipes are laid on a prepared and heat-insulated surface in a spiral, zigzag or snake pattern at a distance of closer than 100 mm and no further than 300 mm from each other. To achieve high efficiency and uniform heat transfer, the length of the circuit should not exceed 75 meters. Therefore, for large rooms or when installing underfloor heating in several rooms, a distribution manifold is installed.

A similar technology is used to arrange surface heating in walls. Pipes with a certain laying pitch are mounted into the wall parallel to the floor and fixed with special fasteners. The coolant moves from top to bottom. The wall base for heat transfer is chalk-cement plaster, which is durable and perfectly decorates pipes. Surface heating does not create forced air movement, due to which heat is evenly distributed over the entire area of the room, creating optimal conditions for living, sleeping and relaxing.

Boiler equipment for low-temperature heating in a private house

The return of the low temperature heating system contains work environment temperature 40-45°C, which is very critical for most classical boiler installations due to the threat of formation of caustic condensate on heat exchange surfaces (dew point). Therefore, the design of low-temperature heating in a private house and the selection of appropriate equipment must be carried out by specialists.

In the case of the actual presence of a heat generator that does not fully meet the temperature requirements for the formation of “soft heat”, it is possible to use a hydraulic arrow or a mixing pump with a thermostat. But the optimal heat source for low-temperature heating is condensing boilers, which are specially designed for this type of heating system. In such boiler installations a special scheme is implemented beneficial use properties of vapors generated during fuel combustion.

Advantages and disadvantages of low-temperature heating in a private house

In comparison with a traditional high-temperature heating system, a scheme using “soft heat” has a significant and at the same time relative disadvantage - the higher cost of the completed project, especially if additional insulation of the house is necessary. Otherwise, low-temperature heating in a private house is characterized only by positive aspects:

ability to maintain higher temperatures (if necessary);
ensuring comfortable indoor conditions without excessive removal of moisture from the air and the formation of air currents that carry dust;
high efficiency (up to 20% or more) due to:

a) separate temperature settings in the circuits;

b) more efficient processing of energy resources;

c) possibility of additional water heating alternative sources heat;

d) the ability to function when the boiler is turned off due to the prompt redistribution of thermal energy accumulated in the heat accumulator;

In a situation where all sources of heat loss have been qualitatively eliminated, low-temperature heating in a private house will quickly pay for itself, even taking into account regular maintenance of the boiler room and rising fuel prices. According to experts, soft temperature conditions, due to their comfort, safety, versatility and efficiency, will compete with high-temperature systems and will eventually take their place.

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Characteristics of low temperature heating system

The question of what low-temperature heating is arises for many people. Typically, such systems are characterized by heating the coolant to 60 degrees Celsius. At the same time, at the entrance to the system it has a temperature of about 40 degrees, and at the exit - about 60. Let's consider how this is achieved.

Temperature heating systems can be described by three characteristics:

. Coolant temperature at the boiler inlet.
. Outlet temperature.
. Temperature in the heated room.

The boiler data must be indicated in the product data sheet in exactly this sequence. Heating systems traditional type(including central heating), were calculated in such a way that at the outlet of the heater the water should have a temperature of about 80 degrees with a temperature of 60 degrees at the inlet. However, these days such indicators are somewhat outdated. The temperature can be reduced either by the heating network or by the user himself. European boilers, which today have almost completely replaced their Soviet heating counterparts, operate according to slightly different schemes.

According to the European standard, the normal operating mode of heating systems assumes a temperature of 60-75 degrees Celsius. But here we also talk about the concept of so-called “soft heat”, which assumes system parameters with temperatures up to 55 degrees. And it is precisely this regime that may become normative in the near future, given all the increasingly stringent requirements for savings. Thus, it becomes increasingly relevant.

ABOUT " warm floors“Perhaps everyone has heard. This system is one of the most bright examples low temperature heating. In addition, most owners of private houses today reduce the boiler temperature to “one” in order to bring the temperature of the coolants to 50-60 degrees.

What are the advantages of low temperature heating?

At installation of a water heated floor system, you get the following benefits:

1. The main advantage is the level of comfort. It's no secret that overly hot radiators dry out the air, forming excessive convection in the house, which raises a lot of dust in the house, having a negative impact on the human body.
2. Cost-effective. By refusing intensive heating in favor of selective heating, which is characterized by separate temperature control, you can save up to 20% of coolants.
3. Technological efficiency. Using mode warm pipes, you can discover two heating options at once - condensing boilers, characterized by an efficiency of up to 95%, and solar collectors, which allow you to get “free” energy.

By eliminating the main sources of heat loss and wanting to reduce costs when the system pays off in 5-10 years, home owners can begin converting their heating systems to a more economical operating mode.

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Heat sources for low temperature heating

In a conventional heating system, the temperature of the water leaving the boiler is much higher and is approximately 70-80 degrees, while the return temperature is 20 degrees lower.

It should be noted that low-temperature heating systems are used not because they are better and more efficient, but because they are the only way to heat a house using heat pumps, geothermal heat sources or condenser heating boilers.

So-called traditional heating boilers in low-temperature systems can only be used in conjunction with an elevator unit, which ensures mixing of cold coolant with hot water from the boiler and bringing the coolant temperature to the required (55-45) parameters.

Long-term operation conventional boiler heating the return at a low temperature can lead to excessive condensation in the chimney and its premature failure. Therefore, in low-temperature heating systems operating on conventional heating boilers, the coolant from the return pipeline must be heated before being supplied to the boiler, using part of the heat generated by the boiler.

All this complicates the design of the heating system and leads not only to an increase in its cost, but also significantly complicates the process of operation and maintenance.

Only condensing heating boilers can operate with low-temperature coolant.

Low temperature sources

As already mentioned, low-temperature heating is focused on the consumption of thermal energy generated by heat pumps, as well as heat obtained from the sun and geothermal heat. These sources are optimal for low-temperature systems. If you decide to use low-temperature heating without the use of renewable energy sources, it is easier and more economical to install a condensing boiler.

But the system for producing “soft heat,” as low-temperature heating is often called, will work only with the right choice of heating devices.

Heating devices for low temperature systems

Conventional radiators are not suitable for low-temperature heating systems. They simply will not be able to work at full capacity, and the house will be cold. Heating a house with a low-temperature heating system will have to be done using heating surfaces. These can be warm floors or warm walls. The relationship is simple: the larger the heating surface, the warmer the house will be.

It should be noted that low-temperature heating systems have a number of advantages:

Heating surfaces with a temperature of approximately 35-40C emit heat in the most comfortable wavelength range for humans
Warm floors allow you to redistribute heat in the room. If, when installing conventional radiators, the warmest air in the room (and with it the warmest zone) is located under the ceiling, then when using heated floors it is located under the feet, which is more natural and comfortable for a person.
The use of geothermal heat and solar energy reduces heating costs and has a positive effect on the environment.

What's more expensive?

Unfortunately, today it is premature to talk about real savings when using low-temperature heating.

In our country, it is cheaper to heat with gas, using traditional boilers complete with convectors and heating radiators.

For those who want to enjoy the gentle warmth from heating surfaces, it is better to install a condensing boiler. It costs more, but allows you to reduce gas consumption by 15-20%.

The temperature regime of heating systems can be described by three characteristics:

. Coolant temperature at the boiler inlet.
. Outlet temperature.
. Temperature in the heated room.

The boiler data must be indicated in the product data sheet in exactly this sequence. Traditional heating systems (including central heating) were designed in such a way that the water leaving the heater should have a temperature of about 80 degrees with a temperature of 60 degrees at the inlet. However, these days such indicators are somewhat outdated. The temperature can be reduced either by the heating network or by the user himself. European boilers, which today have almost completely replaced their Soviet heating counterparts, operate according to slightly different schemes.

Probably everyone has heard about “warm floors”. This system is one of the most striking examples of low-temperature heating. In addition, most owners of private houses today reduce the boiler temperature to “one” in order to bring the temperature of the coolants to 50-60 degrees.

What are the advantages of low temperature heating?

At installation of a water heated floor system, you get the following benefits:

1. The main advantage is the level of comfort. It's no secret that overly hot radiators dry out the air, forming excessive convection in the house, which raises a lot of dust in the house, having a negative impact on the human body.
2. Cost-effective. By refusing intensive heating in favor of selective heating, which is characterized by separate temperature control, you can save up to 20% of coolants.
3. Technological efficiency. Using the warm pipe mode, you can discover two heating options at once - condensing boilers, characterized by an efficiency of up to 95%, and solar collectors, which allow you to get “free” energy.

A. Nikishov

The development of technical thought has allowed to modern man have big choice heating systems, depending on the requirements and material capabilities, which even the previous generation did not have. The gradual development of household heat and power engineering has led to the fact that low-temperature home heating systems, which will be discussed in this article, have become increasingly popular among the population.

Practice has shown that when comparing two heat sources - with high and low temperatures - the most comfortable conditions for a person are created precisely by a low-temperature heating device, which provides a small temperature difference in the room and does not cause negative sensations. The upper limit of the so-called low temperatures, as defined by power engineers, is around 40˚C. Low-temperature heating systems using a coolant operate at temperatures of 40-60˚C - at the inlet to the heat-producing device and at its outlet. And air, electric and radiant heating systems also use lower temperatures, comparable to the temperature of the human body. So the very concept of low temperatures is quite arbitrary and, nevertheless, the use of coolant or other heat sources with temperatures up to 45˚ has many advantages that influence the choice of such a system for heating a home, and, due to its characteristics, fits organically into the use of renewable energy sources.

All heating systems have certain requirements that are designed to make their use more efficient, comfortable and safe. Construction, climatic, hygienic and technological requirements are set out in detail in DBN V.2.5-67:2013 in paragraphs 4, 5, 6, 7, 9, 10 and 11. These requirements make it possible to minimize the negative and at the same time increase the positive effects on the human body, provided by heating systems.

It should be noted that one of the most important conditions for the efficient operation of any heating systems is careful consideration of heat loss, and for low-temperature systems this is perhaps the most important thing. Otherwise, such systems will be ineffective and excessively energy-consuming, and, therefore, materially costly.

Classification

Low-temperature heating systems can be divided into monolithic, bivalent and combined based on the method of heat generation. Monolithic systems are characterized by the use of one or more heat-producing units. Bivalent heat generators use two heat generators that have different operating principles, one of which can be switched on as additional source heat at very low temperatures outside air. Several heat-producing units connected in parallel form a combined heating system.

Heating of the coolant in all heating systems can be carried out directly or indirectly. Example direct heating are water heating boilers various types operating on solid, liquid or gaseous fuels, as well as electric boilers. The coolant is heated indirectly in heat exchangers (boilers) or heat accumulators. This method very widely used in systems powered by renewable energy sources - wind and solar.

Also, low-temperature heating systems can be divided by type of coolant - liquid, gas, air and electric, and by type of heating devices - surface, convection and panel-radiant.

Description of systems

Low-temperature heating systems are becoming increasingly popular due to the fact that they are very harmoniously combined with equipment running on renewable energy sources. At a time when traditional energy is becoming more and more expensive, this is an important factor.

Water heating

All systems of this type are characterized by three main parameters - the temperature of the coolant at the outlet of the heat-producing device (in this case, water heating boilers for solid, liquid, gaseous fuel and electric are used), the temperature at its inlet and the air temperature in the heated room. This sequence of numbers is indicated in all documents for boilers.
Modern low-temperature heating systems are mainly based on the European standard EN422, which introduces the concept of “soft heat”, which involves the use of a coolant with a temperature at the outlet of the heat-producing device of 55˚C, and at the inlet - 45˚C.

This type of heating involves the use of circulation pumps in the system, which are placed in the same way as in conventional heating systems. The most economical are considered to be “open” systems with placement expansion tank at the top point. Installing pumps in the coolant supply line allows you to avoid possible vacuum zones, which occurs when installing circulation pumps on the return line.

In closed systems operating at high pressure, along with circulation pump It is necessary to use an automatic air vent and relief valve, as well as a pressure gauge indicating the pressure in the system. The expansion tank in this case is located in a place convenient for the user.

One of the requirements that determines the efficiency of open-type heating systems is the need for good thermal insulation of the expansion tank. Sometimes - if it is placed in the attics of buildings - its forced heating is also required.

One of the most common types of low-temperature heating systems is the well-known “warm floor” (Fig. 1). Surface heating systems, for example, produced by Oventrop (Germany), include pipes that can be installed in the floor, ceiling, and walls. In this case, the interior is not affected at all.

Rice. 1. Heating system with “warm floor”

In these systems, thanks to predominantly radiant heat exchange, there is absolutely no air movement, and heat is evenly distributed throughout the room. Electronic programmable controllers significantly increase the efficiency of the system.

The supply line of surface heating systems contains a coolant at a temperature of 40-45˚C, which allows using the capabilities of condensing boilers, as well as alternative (renewable) energy sources, with maximum effect. The system typically uses a cross-linked polyethylene pipe with an oxygen barrier layer.

Steam heating

This type of heating is characterized by the use of “saturated” steam as a coolant, which leads to the need to ensure adequate condensate collection. And if there is one heating device in the heating system, which does not create problems, then as their number increases, it becomes more and more difficult to remove the condensate. The solution to this problem was found in using “cold” steam as a coolant. His role in modern systems Low-temperature steam heating is played, in particular, by freon-114 - a non-flammable, non-toxic, odorless and chemically stable inorganic compound.

The “cold” steam system works by using the heat generated by the condensation of saturated steam, which heats the heating devices. Condensate pipelines operate in “wet” mode, which is caused by condensate backwater. In this case, condensate traps are not needed - the condensate returns by gravity to the evaporator. A booster pump is also not required. Both steam and condensate pipelines are mounted both horizontally and vertically. Moreover, it is absolutely not necessary to observe the slope. In the case of vertical installation, the steam supply line can be placed either at the top or at the bottom.

Adjustment of a system operating on “cold” steam is carried out by influencing the steam pressure and its temperature, for which the system is designed for a pressure corresponding to the maximum possible steam temperature.

Sectional radiators and convector panels are usually used as heating devices in a low-temperature steam heating system. To regulate heat transfer, each heating device is equipped with a membrane valve.

Air systems

The use of this type of system (Fig. 2) is quite limited. This is influenced by several factors. Firstly, the degree of heat exchange between the air and the heat-producing device or heat exchanger is quite low. Secondly, for hygienic reasons. Air currents carry dust, and air channels and heat exchange devices create good conditions for the development of unwanted bacteria and microorganisms, and require special protection. And thirdly, such systems are very material-intensive, and therefore have a high cost.

Rice. 2. Air heating system

But despite this, air systems Low temperature heating can be used in the following cases:

if it is necessary to provide centralized heating at low air speed in the channels. This method is suitable for heating small houses and cottages using a baseboard air duct;
if you need to provide central heating with high speed air in the channels - high pressure system. In this case, special air distribution equipment is required to ensure uniform air flow to all rooms and have noise-absorbing properties. Adjustment of this system is carried out in two ways: primary - on the heat exchanger, and secondary - by the amount of supply warm air;
if you need local heating of several rooms or one large one. Such systems are familiar to everyone from large stores - they are also used air curtains at the entrance to the premises, and additional air ducts with warm air in the necessary places.

Electric heating

This system is represented on the heating systems market by many manufacturers. It is based on the principle of heating a special resistive cable (Fig. 3) electric shock. The heat removed from the cable is transferred to environment, creating a gentle heating of the room. The system package may include heating cables or ready-made mats, thermostats and an installation kit that ensures quick and easy installation.

Rice. 3. Electric “warm floor”

Structural elements of systems

All heating systems, as mentioned above, are designed to maintain an optimal and comfortable ratio of three parameters - the temperature of the coolant after the heat-producing device, the temperature of the heating device and the air temperature in the room. This ratio can be achieved correct selection important elements systems.

Heat producing devices

All devices for producing heat can be divided into three groups.

The first group is heat generators based on the use of traditional fuel and electricity. For the most part, these are various water heating boilers operating on solid, liquid, gaseous fuel and electrical energy. Even for indirect heating“cold” steam in steam low-temperature heating systems uses the same water heating devices.

In this group of devices we can note a household condensing boiler, which is a device that appeared as a result of innovative developments in rational use water vapor generated during fuel combustion. Research aimed at improving the use of energy while minimizing the negative impact on the environment has led to the creation of new type heating equipment - condensing boiler - allowing through condensation to obtain extra heat from flue gases.

For example, the Italian manufacturer Baxi produces a line of condensing boilers, both floor-standing and wall-mounted. The lineup wall-mounted boilers Luna Platinum (Fig. 4) consists of single-circuit and double-circuit condensing boilers, with a power from 12 to 32 kW. The key element is the heat exchanger made of of stainless steel AISI 316L. Various components The boiler is controlled by an electronic board, there is a removable control panel with a liquid crystal display and a built-in temperature control function. The burner power modulation system allows the boiler output to be adapted to the energy consumed by the building in a range of 1:10.

Rice. 4. BAXI Luna Platinum condensing boiler

The second group is installations that use heat from off-system coolants. In such cases, heat accumulators are used.

The third group includes devices that use an external coolant for indirect heating. They successfully use surface, cascade or bubbling spherical heat exchangers. This type is used to heat “cold” steam in low-temperature steam heating systems.

Heating devices

Heating devices are divided into 4 groups:

devices with equal surface area, both on the coolant side and on the air side. This type of device is known to everyone - these are traditional sectional radiators;
convection-type devices, in which the surface area in contact with air is much larger than the surface on the coolant side. In these devices, heat radiation is of a secondary nature;
plate air heaters with incentive air flow;
panel type devices - floor, ceiling or wall. In this line of heating panels, for example, we can note the Czech Korado steel panel radiators called Radik, produced in two versions - with a side connection (Klasik), and with a bottom connection with a built-in thermostatic valve (VK). Panel steel radiators are also offered by Kermi (Germany).

Rice. 5. Panel steel radiator Korado

Heating devices for low-temperature systems include various types of sectional and panel heaters, heating convectors, air heaters and heating panels.

Thermal accumulators

These devices are required in bivalent low temperature heating systems that use energy from renewable sources or waste heat. Thermal accumulators can be liquid- or solid-filled, using the heat capacity of the filler to accumulate heat.

Devices in which heat is released at the time of phase transformations are becoming increasingly widespread. Heat accumulates in them during the melting of a substance or when its crystalline structure undergoes certain changes.

Thermochemical heat accumulators also work effectively, the operating principle of which is based on the accumulation of heat as a result chemical reactions, occurring with the release of heat.

Heat accumulators can be connected to the heating system either in a dependent or independent manner, when they accumulate heat from an off-system coolant.

Thermal accumulators can also be ground, rock, and even underground lakes can be used as heat storage.

Ground heat accumulators are obtained by placing registers made of pipes in increments of one and a half to two meters. Rock heat accumulators are constructed by drilling vertical or inclined wells in rock to a depth of 10 to 50 m, where the coolant is pumped. The use of underground lakes as heat accumulators is possible if pipes with coolant pumped into them are placed in the lower layers of water. Heat is removed from pipes located in upper layers underground lakes.

Heat pumps

When using a heat source in low-temperature heating systems, the temperature of which is lower than the air temperature in the room, and also to reduce the material consumption of heating devices, heat pumps can be included in the system (Fig. 6). The most common devices in this group are compression heat pumps, which produce condensation temperatures from 60 to 80˚C.

Rice. 6. Operating principle of the heat pump

Efficient operation of the heat pump in a low-temperature heating system is ensured by inclusion in the evaporator circuit thermal battery, which helps stabilize the evaporation temperature of “cold” steam. Adjustment of this system is carried out by changing the heat output of the pump itself.

Advantages and disadvantages

Low-temperature heating systems win their supporters by creating more comfortable indoor conditions than traditional heating systems with high heating. There is no excessive “drying” of the air, and there is no – again excessive – dustiness in the room due to the inevitable movement of air with very hot heating devices.

The use of heat accumulators in the system makes it possible to accumulate heat and instantly use it if necessary.

The low temperature spread between the heat-producing device and the room air makes it easy to regulate the system using programmable thermostats.

As for the disadvantages, there is essentially only one - the cost of the completed system is several, or even several times higher, than the traditional high-temperature one.

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They are considered attributes of heating systems with a high temperature parameter. But the foundations on which such ideas were built are outdated. Saving metal and thermal insulation is not currently given priority over saving energy resources. And the characteristics of current radiators allow us to talk not only about the likelihood of their use in low-temperature communications, but also about the advantages of such a conclusion. This is substantiated by scientific research carried out over a couple of years at the proposal of the Rettig ICC company, owner of the brands Purmo, Radson, Vogel, Finimetal, Myson. Reducing the temperature of the coolant is the basic trend in the progress of heating technology in recent years in European countries. This was realized as the thermal insulation of buildings improved and heating equipment improved. In the 1980s, the usual parameters were reduced to 75/65 ºC (flow/return). The main advantage of this was the reduction of losses during the formation, transportation and distribution of heat, as well as safety for consumers. Progress regarding water supply does not stand still either. In order to protect the internal surfaces of pipes from corrosion and high levels of wear, use an avk valve. This is a certain element pipeline fittings, the main parts of which are disk-shaped. High performance characteristics The avk shutter is made of carbon nickel plated steel, as well as an epoxy coating. An avk valve is used for water and neutral liquids.

With the increasing popularity of underfloor and other types of panel heating in systems where they are used, the supply temperature has been lowered to the level of 55 ºC, which was taken into account by the creators of heat generators, balancing fittings, etc. Now the supply temperature in ultra-technological heating systems can be 45 and 35 ºC . The impetus for achieving such parameters is the ability to more efficiently operate sources such as heat pumps and condensing boilers. At a secondary circuit medium temperature of 55/45 ºC, the COP efficiency element for a ground-water heat pump is 3.6, and at 35/28 ºC it is already 4.6 (during heating operation). And the use of boilers in a condensing state, which require cooling of flue gases with return water below the “dew mark” (when burning fuel - 47 ºC), gives an efficiency bonus of about 15% or more. Thus, reducing the temperature of the medium provides significant savings in resources and a reduction in the release of carbon dioxide into the air. Until now, the basic solution for supplying heat to rooms at a low temperature of the medium has been “warm floors” and convectors with copper-aluminum exchangers.

Research initiated by Rettig ICC allowed steel panel radiators to be added to this category. With the assistance of several scientific institutions, including those in Helsinki and Dresden, they were tested in various study conditions. The results of other work on the functioning of modern heating communications have also been added to the “evidence base”. At the end of January last year, the research results were presented to journalists from leading European publications at an event held at the Purmo-Radson center in Erpfendorf.

Low-temperature heating systems today are still not widespread in Russia, but they are successfully practiced in Europe, including in countries with not the mildest climates, but where renewable energy sources (RES) are actively used for heating and air-conditioning of buildings. .

G beautiful and obvious advantages Such systems are aimed at saving energy resources based on fossil hydrocarbons in combination with minimizing environmental damage. In addition, low temperature systems provide the user with additional features in achieving thermal comfort in the home and controlling the microclimate of the premises.

In Russia, the scope of application of low-temperature heating systems is limited not only by climatic conditions in many of its regions, but also by standards. In particular, this factor operates in mass construction, on objects such as apartment buildings, for which standards are developed for other modes of heat supply to buildings. Therefore, low-temperature heating systems, if used, are used in social institutions such as clinics and kindergartens, as well as more widely in the private cottage sector. In addition, they are usually designed and installed for heating and air conditioning energy-saving houses, primarily “active” ones, which are last years They also began to be built in Russia. Minimizing heat loss through building boundaries and ventilation is generally one of the main conditions for the successful use of low-temperature heating systems there.

Low-temperature heating systems are being created based on highly efficient heat generators and renewable energy transformers, as well as using modern models heating devices and electronic automation, combined into intelligent control systems.

Generation with accumulation

According to existing regulatory documents The temperature regime of the heating system is characterized by three parameters: the temperature of the coolant at the outlet of the heat generator, at its inlet and the air temperature in the room. The mode where the coolant temperature at the outlet of the heat generator does not exceed 55 °C, and at the inlet is up to 45 °C, is considered characteristic of low-temperature systems. The air temperature in the room is usually taken to be 20 °C. Most common temperature conditions in such systems - 55/45/20 °C, 45/40/20 °C or even 35/30/20 °C.

Low-temperature heating systems can be monovalent, where heat is generated by one heat generator, or, more often, polyvalent, which combines the operation of several heat generators or transformers into heat from renewable energy sources ( rice. 1). Such polyvalent systems are also called hybrid.

Fig.1

A condensing boiler is well suited for both mono- and polyvalent systems (as a peak heat generator). Its operating mode is closest to that indicated above and largely depends on the temperature parameters of the heating system. The lower the coolant temperature in the boiler return circuit, the more complete the steam condensation occurs, more heat will be recycled, higher than the efficiency of the condensing boiler. For gas boilers, the threshold temperature of condensation mode is 57 °C. Therefore, the heating system must be designed to use coolant with a lower temperature in the return circuit.

At average temperatures for the winter period, according to the design calculation, taking into account maximum efficiency condensation mode should not exceed 45 °C. Such parameters are provided by low-temperature heating systems in which condensing boilers operate primarily in their “standard” mode.

Of course, not only condensing boiler technology can and is used in low-temperature systems. The heat generator in such a system, including the peak one, can be any highly efficient boiler operating on any fuel and, in particular, electric. In hybrid systems, the boiler is switched on only at peak loads, when other heat generators (renewable energy transformers - solar collectors, heat pumps) cannot cope with providing thermal comfort in heated rooms and the needs of hot water supply.

When using renewable energy, low-temperature water heating systems usually include heat accumulators, which can be with liquid and solid fillers, phase (using the heat of phase transformations) and thermochemical (heat is accumulated due to endothermic reactions and released during exothermic ones).

In heat accumulators with liquid and solid fillers (water, low-freezing liquids (ethylene glycol solution), gravel, etc.), heat accumulates due to the heat capacity of the filler material. In phase heat accumulators, heat accumulation occurs during melting or a change in the crystalline structure of the filler, and release occurs during its hardening.

The most widespread in hybrid low-temperature water heating systems installed in cottages are water storage tanks that successfully dampen peak hot water loads, storing heat from the operation of a solar collector, heat pump or (in winter) a peak heat generator. By accumulating thermal energy from various sources, such a heat accumulator allows optimizing their operation from the point of view of maximum economic efficiency at a particular moment, reserving “cheap” heat. The excess heat generated can be used for hot water supply. Their use is also justified when using heat pumps to optimize the operation of compressors and hydraulic decoupling of the heat pump circuits and the load.

The heat accumulator water tank is a well-insulated container, for example, with a layer of polyurethane foam 80-100 mm thick, into which several heat exchangers are built. A heat accumulator with a volume of 0.25-2 m 3 can accumulate 14-116 kWh of thermal energy.

Devices for low temperature heating systems

The low temperature of the coolant determines the choice of devices for low-temperature heating systems, which must effectively transfer heat into heated rooms, operating in a flexible mode. If these devices are installed in a cottage where the coolant pressure in the pipelines is obviously low, then their strength characteristics fade into the background.

Fig.2

According to experts, the most successful low-temperature systems use wall-mounted, parapet or floor-mounted convectors with forced ventilation (rice. 2) and steel panel radiators ( rice. 3). In such systems, convectors equipped with a heat exchanger with a large surface area should be used - multilayer with frequent fins and a fan that provides large heat removal. In addition to convectors, these conditions are also met by wall-mounted and ceiling-mounted fan coil units (fan coils).

Fig.3

In forced convection systems without a fan, ejection closers can be used. Due to efficient heat removal and high power, these devices will have small dimensions compared to other types of equipment.

The advantage of such devices is the possibility of their use in combined systems that heat rooms during the cold season and are used to cool air in the summer.

If convectors without a fan are used in low-temperature systems, their height must be at least 400 mm.

The coolant panel of a steel panel radiator is located outside the heating device. The lamellas of the convective element are heated from it. The farther from the panel, the cooler the lamellas. Convection at low radiator temperatures is hindered by the viscosity of the air sandwiched between the lamellas. But nothing interferes with thermal radiation from the panel.

Steel panel radiators are successfully used in low-temperature heating systems also because their model lines include a wide range of standard sizes, and this is important for optimal placement heating devices in such systems, in particular, heating devices must be installed in them that cover the entire length of the window opening.

Fig.4

Operation of convectors with forced ventilation and steel panel radiators will be successfully combined with a warm water floor ( rice. 4), which is literally designed to work with coolant characterized by low temperatures. According to SNiP 41-01-2003 “Heating, ventilation and air conditioning”, clause 6.5.12, the average surface temperature of floors with built-in heating elements should be taken no higher than 26 ° C - for rooms with constant occupancy; and not higher than 31 °C - for premises with temporary occupancy of people. Floor surface temperature along the axis heating element in children's institutions, residential buildings and swimming pools should not exceed 35 °C. In real conditions, with existing technologies for installing heated floors, such surface temperatures are achieved at coolant temperatures at the entrance to the heated floor pipeline no higher than 45 °C.

Warm floors significantly increase the efficiency of low-temperature heating systems. Thus, when installing a heated floor, the energy reserve of a water heat accumulator with a capacity of 1.2 m 3 is sufficient to heat a house with an area of 130-140 m 2 using electricity received at a low night tariff.

All water heating devices in low-temperature heating systems are equipped with automatic thermostatic control.

Intelligent Control

Since most low-temperature systems are hybrid, and it is also possible to combine heating and air conditioning functions in one such system, their greatest efficiency and economy can be achieved with rational management of all components of the system. Today, smart control systems are used for this.

Without intelligent control, it is impossible to effectively and at the same time flexibly regulate the system based on real sensor readings, and not on built-in graphs that do not take into account the conditions of a particular heat supply facility. When a project uses smart control, you only need to set the initial settings, and then the intelligent automation will automatically support them.

The smart controller is responsible for switching the system from one heat source to another. By processing several inputs every second, the controller selects the most economical heat source at the moment. According to the given logic, thermal energy from the cheapest source is used first.

The use of such intelligent control systems makes it possible to differentially set temperatures in controlled rooms, thereby achieving, in addition to efficiency, also highest level thermal comfort.

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