Minimum gas boiler temperature. Optimal operation of the heating boiler

Tell me about boilers and timing. When the set coolant temperature is reached, should the boiler reduce gas consumption and reach the minimum (or so) power? As a result, there should be no clocking. Unless the minimum power turns out to be more than necessary to maintain the set coolant temperature.

Then the question is: how to find out the power range of the boiler (or, equivalently, the gas flow range). With the maximum it is clear - it is indicated everywhere.

Click to reveal...

In one room? As if in each individual room, the temperature can change (by + - 1 gram at least) for reasons independent of the weather and the boiler (they opened the door to the next room, where the temperature is different, opened the window, people came in, turned on the .-l powerful device, the wind direction changed to the opposite - as a result, the temperature difference in the rooms was 1g: at one end of the house + 0.5g, at the other -0.5, total 1g, and so on). 1 degree is enough. For the whole house, 1 degree is very, very decent. You need to spend a lot of cubic meters of gas to raise the temperature in the house by 1 degree (especially if the house is > 200 square meters). And it turns out that for one sensor in one room, the boiler will have to scald at full power for a long time. And then the conditions in a particular room where the sensor will change, and the boiler will have to turn off abruptly. And heating is a very inertial thing. There is a decent amount of water (hundreds of liters, if the house is not small), in order to raise the temperature in the premises by 1g, you must first heat all this water and only then will it give off heat to the premises of the house. As a result, the coolant will heat up, and in the room where the sensor is located, the conditions have already changed (the device was turned off, a lot of people left, the door to the next room was closed). That is, it seems like a signal to the boiler to lower the temperature IN THE WHOLE HOUSE, and the coolant is already heated, and there is nowhere to go, it will give off its heat to the house when, judging by the sensor in one room, it needs to be reduced .....

In general, the point is that it is probably not very correct to determine the operation of the boiler for the whole house from one temperature measurement point in the house, because. if the room is "usual", then the temperature fluctuations independent of the weather and the operation of the boiler are too large (more precisely, sufficient to change the operating mode of the boiler THEN, when the change in the integral temperature throughout the house is NOT ENOUGH to change the operating modes of the boiler), and will lead to a change in the operating mode of the boiler when it is not really necessary.

You need to know the integral temperature around the house - then, based on this temperature, you can determine the operating mode of the boiler. Because the integral temperature around the house (especially in a large house) changes very, VERY slowly (if the heating is completely turned off, it will take more than 4 hours for it to fall by 1 g) - and this temperature changes by at least 0.5 g. - this is already a sufficient signal to increase the gas flow to the boiler. From simple opening doors, from the fact that there are much more people in the house, etc. - from all this, the integral heat in the house will not change even by 0.1g. Bottom line - you need a bunch of sensors for different rooms and then reduce all readings into one average (at the same time, for good, take not just the average, but the integral average, i.e. take into account not only the temperature of each specific sensor, but also the volume of the room in which this sensor is located).

P.S. For relatively small houses (probably 100m or less), probably, all of the above is not critical.

P.P.S. All of the above - imho

External low-temperature corrosion occurs as a result of the formation of drops or a film of moisture on the heating surfaces and reacts with the metal surface.

Moisture appears on the heating surfaces during the condensation of water vapor from flue gases due to the low temperature of the water (air) and, accordingly, the low temperature of the wall.

The dew point temperature at which water vapor condenses depends on the type of fuel burned, its moisture content, excess air coefficient, and on the partial pressure of water vapor in the combustion products.

It is possible to exclude the occurrence of low-temperature corrosion on heating surfaces when the surface temperature on the side of the gaseous medium is 5°C higher than the dew point temperature. This value of the dew point temperature corresponds to the condensation temperature of pure water vapor and appears during fuel combustion.

When fuel (fuel oil) that contains sulfur is burned, sulfuric anhydride is formed in the combustion products. Part of this gas, being oxidized, forms aggressive sulfuric anhydride, which, dissolving in water, forms a film of sulfuric acid solution on the heating surfaces, as a result, it sharply increases corrosion process. The presence of sulfuric acid vapor in the combustion products increases the dew point temperature and causes corrosion in those areas of the heating surface, the temperature of which is much higher than the dew point temperature and when burning natural gas is 55 ° C, when burning fuel oil - 125 ... 150 ° C.

In steam boilers, for most cases, the temperature of the water entering the economizer exceeds the required temperature because the water comes from the deaerators atmospheric type with a temperature of 102 ° C.

This issue is more difficult to solve for hot water boilers, since the temperature of the coolant in the external pipeline of the heat supply system entering the boilers depends on the outside air temperature.

It is possible to increase the temperature of the incoming water to the boiler by recirculating hot water from the boiler.

The efficiency and reliability of the water heating system of a hot water boiler depends on the flow rate of the coolant through the recirculation. With an increase in pumping, the temperature of the water entering the boiler increases, the temperature of the exhaust gases also increases, which means that the efficiency of the boiler decreases. The power consumption for the drive of the recirculation pump in this case increases.

Operating instructions for hot water boilers propose to regulate the operation of the heating water heating system in such a way that the temperature of the water at the inlet to the boilers during the combustion of natural gas does not fall below 60 ° C. This requirement reduces the efficiency of their operation, since anti-corrosion measures to maintain the temperature of the walls of the heating surfaces can be provided if the temperature is below 60 ° C. But in this case, it is necessary to take into account the temperature of the walls of the heating surface in the calculations.

An analysis of such calculations shows that, for example, for hot water boilers operating on natural gas, at a gas temperature of 140 ° C, the temperature of the water at the inlet to the boiler must be maintained at least 40 ° C, i.e. below 60 ° C, which the instructions suggest.

Thus, by changing the mode of operation of hot water boilers, it is possible to save heat and electricity in the absence of low-temperature corrosion of metal surfaces of hot water boilers.

2.KIT of the boiler at different temperatures of the incoming

The lower the temperature enters the boiler, the greater the temperature difference on different sides of the boiler heat exchanger partition, and the more efficiently the heat passes from the exhaust gases (combustion products) through the heat exchanger wall. I will give an example with two identical kettles placed on the same burners. gas stove. One burner is set to high flame and the other to medium. The kettle with the highest flame will boil faster. And why? Because the temperature difference between the combustion products under these kettles and the water temperature for these kettles will be different. Accordingly, the rate of heat transfer at a larger temperature difference will be greater.

With regard to the heating boiler, we cannot increase the combustion temperature, as this will lead to the fact that most of our heat (gas combustion products) will fly out through the exhaust pipe into the atmosphere. But we can design our heating system (hereinafter CO) in such a way as to lower the temperature entering into , and therefore, lower the average temperature circulating through . The average temperature at the return (inlet) to and supply (outlet) from the boiler will be called the temperature of "boiler water".

As a rule, the 75/60 ​​mode is considered the most economical thermal mode of operation of a non-condensing boiler. Those. with a temperature at the supply (outlet from the boiler) +75 degrees, and at the return (inlet to the boiler) +60 degrees Celsius. A reference to this thermal regime is in the boiler passport, when indicating its efficiency (usually indicate the mode 80/60). Those. in a different thermal regime, the efficiency of the boiler will be lower than stated in the passport.

Therefore, a modern heating system must operate in the design (for example, 75/60) thermal regime for the entire heating period, regardless of the outside temperature, except when using an outside temperature sensor (see below). The regulation of the heat transfer of heating devices (radiators) during the heating period should be carried out not by changing the temperature, but by changing the amount of flow through the heating devices (the use of thermostatic valves and thermoelements, i.e. "thermal heads").

In order to avoid the formation of acid condensate on the boiler heat exchanger, for a non-condensing boiler, the temperature in its return (inlet) should not be lower than +58 degrees Celsius (usually taken with a margin of +60 degrees).

I will make a reservation that the ratio of air and gas entering the combustion chamber is also of great importance for the formation of acid condensate. The more excess air entering the combustion chamber, the less acidic condensate. But you should not rejoice at this, since excess air leads to a large overspending of gas fuel, which ultimately "beats us in the pocket."

For example, I will give a photo showing how acid condensate destroys the boiler heat exchanger. Pictured is a heat exchanger. wall boiler Vaillant, who worked for only one season in an incorrectly designed heating system. Quite strong corrosion is visible on the return (inlet) side of the boiler.

For condensation, acid condensate is not terrible. Since the heat exchanger of the condensing boiler is made of special high-quality alloyed stainless steel, which is “not afraid” of acid condensate. Also, the design of the condensing boiler is designed so that acidic condensate flows through a tube into a special container for collecting condensate, but does not fall on any electronic components and components of the boiler, where it could damage these components.

Some condensing boilers are able to change the temperature on their return (inlet) by themselves due to the smooth change in the power of the circulation pump by the boiler processor. Thereby increasing the efficiency of gas combustion.

For additional gas savings, use the connection of the outdoor temperature sensor to the boiler. Most wall-mounted ones have the ability to automatically change the temperature depending on the outside temperature. This is done so that at outdoor temperatures that are warmer than the temperature of the cold five-day period (the most very coldy), lower the boiler water temperature automatically. As mentioned above, this reduces gas consumption. But when using a non-condensing boiler, it is important not to forget that when the temperature of the boiler water changes, the temperature at the return (inlet) of the boiler should not fall below +58 degrees, otherwise acid condensate will form on the boiler heat exchanger and destroy. To do this, when commissioning the boiler, in the boiler programming mode, such a curve of temperature dependence on the outside temperature is selected, at which the temperature in the boiler return would not lead to the formation of acid condensate.

I want to warn you right away that when using a non-condensing boiler and plastic pipes in the heating system, installing a street temperature sensor is almost pointless. Since we can design for the long-term service of plastic pipes, the temperature at the boiler supply is not higher than +70 degrees (+74 during the cold five-day period), and in order to avoid the formation of acid condensate, design the temperature at the boiler return is not lower than +60 degrees. These narrow "frames" make the use of weather-dependent automation useless. Since such frames require temperatures in the range of +70/+60. Already when using copper or steel pipes in the heating system, it already makes sense to use weather-compensated automation in heating systems, even when using a non-condensing boiler. Since it is possible to design the thermal mode of the boiler 85/65, which mode can be changed under the control of weather-dependent automation, for example, up to 74/58 and save on gas consumption.

I will give an example of an algorithm for changing the temperature at the boiler supply depending on the outside temperature using the Baxi Luna 3 Komfort boiler as an example (below). Also, some boilers, for example, Vaillant, can maintain the set temperature not on their supply, but on their return. And if you set the return temperature maintenance mode to +60, then you can not be afraid of the appearance of acid condensate. If at the same time the temperature at the boiler supply changes up to +85 degrees inclusive, but if you use copper or steel pipes, then such a temperature in the pipes does not reduce their service life.

From the graph, we see that, for example, when choosing a curve with a coefficient of 1.5, it will automatically change the temperature at its supply from +80 at a street temperature of -20 degrees and below, to a supply temperature of +30 at a street temperature of +10 (in the middle section flow temperature curve +.

But how much the supply temperature of +80 will reduce the service life of plastic pipes (Reference: according to manufacturers, the warranty service life plastic pipe at a temperature of +80, it is only 7 months, so do not hope for 50 years), or a return temperature below +58 will reduce the life of the boiler, unfortunately, there is no exact data announced by the manufacturers.

And it turns out that when using weather-dependent automation with non-condensing gas, you can save something, but it is impossible to predict how much the service life of the pipes and the boiler will decrease. Those. in the above case, the use of weather-compensated automation will be at your own peril and risk.

Thus, it makes the most sense to use weather-compensated automation when using a condensing boiler and copper (or steel) pipes in the heating system. Since weather-dependent automation will be able to automatically (and without harm to the boiler) change the thermal regime of the boiler from, for example, 75/60 ​​for a cold five-day period (for example, -30 degrees outside) to the 50/30 mode (for example, +10 degrees outside) street). Those. you can painlessly choose the dependence curve, for example, with a coefficient of 1.5, without fear of a high boiler supply temperature in frost, at the same time without fear of the appearance of acid condensate during thaws (for condensation, the formula is valid that the more acid condensate is formed in them, the more they save gas). For interest, I will lay out a graph of the dependence of the KIT of a condensing boiler, depending on the temperature in the return of the boiler.

3.KIT of the boiler depending on the ratio of the mass of gas to the mass of air for combustion.

The more completely the gas fuel burns in the combustion chamber of the boiler, the more heat we can get from burning a kilogram of gas. The completeness of gas combustion depends on the ratio of the mass of gas to the mass of combustion air entering the combustion chamber. This can be compared to the tuning of a carburetor in a car's internal combustion engine. The better the carburetor is tuned, the less for the same engine power.

To adjust the ratio of the mass of gas to the mass of air in modern boilers, a special device is used that doses the amount of gas supplied to the combustion chamber of the boiler. It is called a gas fitting or an electronic power modulator. The main purpose of this device is automatic modulation of the boiler power. Also, the adjustment of the optimal ratio of gas to air is carried out on it, but already manually, once during commissioning of the boiler.

To do this, when commissioning the boiler, you must manually adjust the gas pressure using a differential pressure gauge on special control fittings of the gas modulator. Two pressure levels are adjustable. For maximum power mode, and for minimum power mode. The methodology and instructions for setting up are usually set out in the boiler's passport. You can not buy a differential pressure gauge, but make it from a school ruler and a transparent tube from a hydraulic level or a blood transfusion system. The gas pressure in the gas line is very low (15-25 mbar), less than when a person exhales, therefore, in the absence of an open fire nearby, such a setting is safe. Unfortunately, not all service workers, when commissioning the boiler, perform the procedure for adjusting the gas pressure on the modulator (out of laziness). But if you need to get the most economical operation of your heating system in terms of gas consumption, then you must definitely perform such a procedure.

Also, when commissioning the boiler, it is necessary, according to the method and table (provided in the boiler passport), to adjust the diaphragm cross section in the boiler air pipes, depending on the boiler power and the configuration (and length) of the exhaust pipes and combustion air intake. The correctness of the ratio of the volume of air supplied to the combustion chamber to the volume of supplied gas also depends on the correct choice of this section of the diaphragm. Correct this ratio ensures the most complete combustion of gas in the combustion chamber of the boiler. And, therefore, it reduces to necessary minimum gas consumption. I will give (for an example of a technique correct installation aperture) scan from the passport of the boiler Baxi Nuvola 3 Comfort -

P.S. Some of the condensers, in addition to controlling the amount of gas supplied to the combustion chamber, also control the amount of air for combustion. To do this, they use a turbocharger (turbine) whose power (revs) is controlled by the boiler processor. This skill of the boiler gives us an additional opportunity to save gas consumption in addition to all the above measures and methods.

4. KIT of the boiler, depending on the temperature of the air entering it for combustion.

Also, the economy of gas consumption depends on the temperature of the air entering the combustion chamber of the boiler. The efficiency of the boiler given in the passport is valid for the temperature of the air entering the combustion chamber of the boiler +20 degrees Celsius. This is due to the fact that when colder air enters the combustion chamber, part of the heat is spent on heating this air.

Boilers are "atmospheric", which take air for combustion from the surrounding space (from the room in which they are installed) and "turbo boilers" with a closed combustion chamber, into which air is forcibly supplied by a turbocharger located in. Ceteris paribus, a "turbo boiler" will have greater gas consumption efficiency than an "atmospheric" one.

If everything is clear with the “atmospheric” one, then with the “turbo boiler” questions arise from where it is better to take air into the combustion chamber. The “Turboboiler” is designed so that the air flow into its combustion chamber can be arranged from the room in which it is installed, or directly from the street (using a coaxial chimney, i.e. a “pipe in pipe” chimney). Unfortunately, both of these methods have their pros and cons. When air enters from the interior of the house, the temperature of the air for combustion is higher than when taken from the street, but all the dust generated in the house is pumped through the combustion chamber of the boiler, clogging it. The combustion chamber of the boiler is especially clogged with dust and dirt during finishing works in home.

Do not forget that for the safe operation of an "atmospheric" or "turbo boiler" with air intake from the premises of the house, it is necessary to organize the correct operation of the supply part of the ventilation. For example, supply valves on the windows of the house must be installed and opened.

Also, when removing the products of combustion of the boiler up through the roof, it is worth considering the cost of manufacturing an insulated chimney with a steam trap.

Therefore, the most popular (including for financial reasons) are the coaxial chimney systems “through the wall to the street”. Where exhaust gases are emitted through the inner pipe, and outer pipe air for combustion is pumped in from the street. In this case, the exhaust gases heat up the air drawn in for combustion, since the coaxial pipe acts as a heat exchanger.

5.KIT of the boiler depending on the time of continuous operation of the boiler (lack of “clocking” of the boiler).

Modern boilers they themselves adjust their generated thermal power to the thermal power consumed by the heating system. But the limits of auto-tuning power are limited. Most non-condensing units can modulate their power from about 45% to 100% of rated power. Condensing modulate power in a ratio of 1 to 7 and even 1 to 9. Ie. a non-condensing boiler with a rated power of 24 kW will be able to produce at least, for example, 10.5 kW in continuous operation. And condensing, for example, 3.5 kW.

If at the same time the temperature outside is much warmer than in a cold five-day period, then there may be a situation where the heat loss of the house is less than the minimum possible generated power. For example, the heat loss of a house is 5 kW, and the minimum modulated power is 10 kW. This will lead to periodic shutdown of the boiler when the set temperature at its supply (output) is exceeded. It may happen that the boiler will turn on and off every 5 minutes. Frequent switching on / off of the boiler is called “clocking” of the boiler. Clocking, in addition to reducing the life of the boiler, also significantly increases gas consumption. I will compare the gas consumption in the clocking mode with the gasoline consumption of the car. Consider that the gas consumption during clocking is driving in city traffic jams in terms of fuel consumption. And the continuous operation of the boiler is driving along a free highway in terms of fuel consumption.

The fact is that the boiler processor contains a program that allows the boiler, using the sensors built into it, to indirectly measure the thermal power consumed by the heating system. And adjust the generated power to this need. But this boiler takes from 15 to 40 minutes, depending on the capacity of the system. And in the process of adjusting its power, it does not work in the optimal mode in terms of gas consumption. Immediately after switching on, the boiler modulates the maximum power and only over time, gradually, by approximation, reaches the optimal gas flow. It turns out that when the boiler cycles more than 30-40 minutes, it does not have enough time to reach the optimal mode and gas flow. Indeed, with the beginning of a new cycle, the boiler begins the selection of power and mode again.

To eliminate the clocking of the boiler, it is installed room thermostat. It is better to install it on the first floor in the middle of the house and if there is a heater in the room where it is installed, then the IR radiation of this heater should reach the room thermostat at a minimum. Also on this heater, a thermoelement (thermal head) on a thermostatic valve should not be installed.

Many boilers are already equipped with a remote control panel. Inside this control panel is the room thermostat. Moreover, it is electronic and programmable according to the time zones of the day and the days of the week. Programming the temperature in the house by time of day, by day of the week, and when you leave for a few days, also allows you to save a lot on gas consumption. Instead of a removable control panel, a decorative cap is installed on the boiler. For example, I will give a photo of the Baxi Luna 3 Komfort removable control panel installed in the hall of the first floor of the house, and a photo of the same boiler installed in the boiler room attached to the house with a decorative plug installed instead of the control panel.

6. Use of a greater share of radiant heat in heating devices.

You can also save any fuel, not just gas, by using heaters with a greater proportion of radiant heat.

This is explained by the fact that a person does not have the ability to feel exactly the temperature of the environment. A person can only feel the balance between the amount of heat received and given off, but not the temperature. Example. If we take an aluminum blank with a temperature of +30 degrees, it will seem cold to us. If we pick up a piece of foam plastic with a temperature of -20 degrees, then it will seem warm to us.

In relation to the environment in which a person is located, in the absence of drafts, a person does not feel the temperature of the surrounding air. But only the temperature of the surrounding surfaces. Walls, floors, ceilings, furniture. I will give examples.

Example 1. When you go down to the cellar, after a few seconds you become chilly. But this is not because the air temperature in the cellar, for example, is +5 degrees (after all, air in a stationary state is the best heat insulator, and you could not freeze from heat exchange with air). And from the fact that the balance of the interchange of radiant heat with the surrounding surfaces has changed (your body has an average surface temperature of +36 degrees, and the cellar has an average surface temperature of +5 degrees). You begin to give off much more radiant heat than you receive. That's why you get cold.

Example 2. When you are in a foundry or steel shop (or just near a large fire), you get hot. But this is not because the air temperature is high. In winter, with partially broken windows in the foundry, the air temperature in the shop can be -10 degrees. But you are still very hot. Why? Of course, the air temperature has nothing to do with it. The high temperature of the surfaces, not the air, changes the balance of radiant heat transfer between your body and the environment. You begin to receive much more heat than you radiate. Therefore, people working in foundries and steel-smelting shops are forced to put on cotton trousers, padded jackets and hats with earflaps. To protect not from the cold, but from too much radiant heat. To avoid heatstroke.

From this we draw a conclusion that many modern heating specialists do not realize. That it is necessary to heat the surfaces surrounding a person, but not the air. When we heat only the air, first the air rises to the ceiling, and only then, descending, the air heats the walls and the floor due to the convective circulation of air in the room. Those. first, warm air rises under the ceiling, heating it, then descends to the floor along the far side of the room (and only then the floor surface begins to heat up) and then in a circle. With this purely convective method of space heating, there is an uncomfortable temperature distribution throughout the room. When the room temperature is highest at head level, average at waist level, and lowest at foot level. But you probably remember the proverb: "Keep your head cold and your feet warm!".

It is no coincidence that the SNIP states that in a comfortable home, the temperature of the surfaces of the outer walls and floor should not be lower than the average temperature in the room by more than 4 degrees. Otherwise, there is an effect that is both hot and stuffy, but at the same time chilly (including on the legs). It turns out that in such a house you need to live "in shorts and felt boots."

So, from afar, I was forced to lead you to the realization of which heating devices are best used in the house, not only for comfort, but also for fuel economy. Of course, heaters, as you may have guessed, must be used with the greatest proportion of radiant heat. Let's see which heating appliances give us the largest share of radiant heat.

Perhaps, such heating devices include the so-called "warm floors", as well as "warm walls" (which are gaining more and more popularity). But even among the usually most common heating devices, steel panel radiators, tubular radiators and cast iron radiators. I have to assume that steel panel radiators provide the largest share of radiant heat, since manufacturers of such radiators indicate the share of radiant heat, while manufacturers of tubular and cast-iron radiators keep this secret. I also want to say that aluminum and bimetallic "radiators" that have recently received aluminum and bimetallic "radiators" do not have the right to be called radiators at all. They are called so only because they are the same sectional as cast-iron radiators. That is, they are called "radiators" simply "by inertia." But according to the principle of their action, aluminum and bimetal radiators should be classified as convectors, not radiators. Since the share of radiant heat they have is less than 4-5%.

For panel steel radiators, the proportion of radiant heat varies from 50% to 15%, depending on the type. The largest share of radiant heat is in type 10 panel radiators, in which the share of radiant heat is 50%. Type 11 has 30% radiant heat. Type 22 has 20% radiant heat. Type 33 has 15% radiant heat. There are also steel panel radiators produced using the so-called X2 technology, for example, from Kermi. It represents type 22 radiators, in which it passes first along the front plane of the radiator, and only then along the rear plane. Due to this, the temperature of the front plane of the radiator increases relative to the rear plane, and, consequently, the share of radiant heat, since only IR radiation from the front plane enters the room.

The respected firm Kermi claims that when using radiators made using X2 technology, fuel consumption is reduced by at least 6%. Of course, he personally did not have the opportunity to confirm or refute these figures in laboratory conditions, but based on the laws of thermal physics, the use of such technology really saves fuel.

Findings. I advise you to use steel panel radiators in the entire width of the window opening in a private house or cottage, in descending order of preference by type: 10, 11, 21, 22, 33. When the amount of heat loss in the room, as well as the width of the window opening and the height of the window sill do not allow using types 10 and 11 (not enough power) and the use of types 21 and 22 is required, then if there is a financial opportunity, I will advise you to use not the usual types 21 and 22, but using the X2 technology. Unless, of course, the use of X2 technology pays off in your case.

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After installing the heating system, it is necessary to adjust the temperature regime. This procedure must be carried out in accordance with existing standards.

The requirements for the temperature of the coolant are set out in the regulatory documents that establish the design, installation and use engineering systems residential and public buildings. They are described in the State building codes and regulations:

• DBN (B. 2.5-39 Heat networks);
• SNiP 2.04.05 "Heating, ventilation and air conditioning".

For the calculated temperature of the water in the supply, the figure is taken that is equal to the temperature of the water at the outlet of the boiler, according to its passport data.

For individual heating to decide what should be the temperature of the coolant, should be taking into account such factors:

1. Beginning and end heating season on average daily temperature outside +8 °C for 3 days;
2. The average temperature inside the heated premises of housing and communal and public interest should be 20 °C, and for industrial buildings 16 °C;
3. The average design temperature must comply with the requirements of DBN V.2.2-10, DBN V.2.2.-4, DSanPiN 5.5.2.008, SP No. 3231-85.

According to SNiP 2.04.05 "Heating, ventilation and air conditioning" (clause 3.20), the coolant limit values ​​are as follows:

Depending on external factors, the water temperature in the heating system can be from 30 to 90 °C. When heated above 90 ° C, dust begins to decompose and paintwork. For these reasons sanitary norms prohibit more heating.

To calculate the optimal indicators, special graphs and tables can be used, in which the norms are determined depending on the season:

• With an average value outside the window of 0 °С, the supply for radiators with different wiring is set at a level of 40 to 45 °С, and the return temperature is from 35 to 38 °С;
• At -20 °С, the supply is heated from 67 to 77 °С, while the return rate should be from 53 to 55 °С;
• At -40 ° C outside the window for all heating devices set the maximum allowable values. At the supply it is from 95 to 105 ° C, and at the return - 70 ° C.

Optimal values ​​in an individual heating system

H2_2

Heating system helps to avoid many problems that arise with a centralized network, and the optimal temperature of the coolant can be adjusted according to the season. In the case of individual heating, the concept of norm includes the heat transfer of a heating device per unit area of ​​​​the room where this device is located. The thermal regime in this situation is provided by the design features of the heating devices.

It is important to ensure that the heat carrier in the network does not cool below 70 °C. 80 °C is considered optimal. It is easier to control heating with a gas boiler, because manufacturers limit the possibility of heating the coolant to 90 ° C. Using sensors to adjust the gas supply, the heating of the coolant can be controlled.

It is a little more difficult with solid fuel devices, they do not regulate the heating of the liquid, and can easily turn it into steam. And it is impossible to reduce the heat from coal or wood by turning the knob in such a situation. At the same time, the control of heating of the coolant is rather conditional with high errors and is performed by rotary thermostats and mechanical dampers.

Electric boilers allow you to smoothly adjust the heating of the coolant from 30 to 90 ° C. They are equipped excellent system overheating protection.

One-pipe and two-pipe lines

The design features of a single-pipe and two-pipe heating network determine different standards for heating the coolant.

For example, for a single-pipe line, the maximum rate is 105 ° C, and for a two-pipe line - 95 ° C, while the difference between the return and supply should be, respectively: 105 - 70 ° C and 95 - 70 ° C.

Matching the temperature of the heat carrier and the boiler

Regulators help to coordinate the temperature of the coolant and the boiler. These are devices that create automatic control and correction of the return and supply temperatures.

The return temperature depends on the amount of liquid passing through it. The regulators cover the liquid supply and increase the difference between the return and supply to the level that is needed, and the necessary pointers are installed on the sensor.

If it is necessary to increase the flow, then a boost pump can be added to the network, which is controlled by a regulator. To reduce the heating of the supply, a “cold start” is used: that part of the liquid that has passed through the network is again transferred from the return to the inlet.

The regulator redistributes the supply and return flows according to the data taken by the sensor, and ensures strict temperature norms heating networks.

Ways to reduce heat loss

The above information will help to be used for the correct calculation of the coolant temperature norm and will tell you how to determine the situations when you need to use the regulator.

But it is important to remember that the temperature in the room is affected not only by the temperature of the coolant, outdoor air and wind strength. The degree of insulation of the facade, doors and windows in the house should also be taken into account.

To reduce the heat loss of housing, you need to worry about its maximum thermal insulation. Insulated walls, sealed doors, metal-plastic windows help reduce heat loss. It will also reduce heating costs.

05.09.2018

They are almost never equipped with circulation pumps, a safety group, adjustment and control devices. Everyone solves these issues on their own, choosing a heating device piping scheme in accordance with the type and features of the heating system. Not only the efficiency and productivity of heating, but also its reliable, trouble-free operation depend on how correctly the installation of the heat generator is carried out. That is why it is important to include components and devices in the circuit that will ensure the durability of the heating unit and its protection in case of emergency. In addition, when installing a solid fuel boiler, you should not give up equipment that creates additional convenience and comfort. With the help of a heat accumulator, it is possible to solve the problem of temperature differences during the reboot of the boiler, and an indirect heating boiler will provide the house with hot water. Thinking about connecting a solid fuel heating unit in accordance with all the rules? We will help you with this!

However, if the rooms warm up afterwards, hydraulic adjustment is recommended in connection with the renewal of the heating system. The hydraulic adjustment is especially useful when using condensing boilers. These devices only operate at their best possible efficiency if the return temperature is below the temperature at which water condenses from the boiler flue gas. Special cases are single-pipe heating systems, especially in apartment buildings, and buildings with underfloor heating or mixed underfloor heating and radiator heating.

Typical piping schemes for solid fuel boilers

The complexity of controlling the combustion process in solid fuel boilers leads to a large inertia of the heating system, which negatively affects the convenience and safety during operation. The situation is further complicated by the fact that the efficiency of units of this type directly depends on the temperature of the coolant. For effective work heating, the piping must ensure the temperature of the heating agent in the range of 60 - 65 ° C. Of course, if the equipment is not properly integrated, such heating at a positive temperature "overboard" will be very uncomfortable and uneconomical. In addition, the full operation of the heat generator depends on a number of additional factors - such as heating system, the number of circuits, the presence of additional energy consumers, etc. The strapping schemes presented below take into account the most common cases. If none of them meets your requirements, then knowledge of the principles and features of the structure of heating systems will help in the development of an individual project.

Hydraulic adjustment can also be carried out using these heating systems in principle, but is usually associated with much more high costs. Accurate characterization of the heating system boiler is only possible if the heat loss of a structural furnace can be relatively labor intensive. This calculation of heat load ≡ Heating load ≡ Heating load is the heating power that must be constantly supplied to the room in order to maintain the temperature in the space, so it must be as large as the sum of heat loss from conduction and ventilation.

System open type with natural circulation in a private house First of all, it should be noted that open gravity-type systems are considered the most suitable for solid fuel boilers. This is due to the fact that even in emergency cases associated with a sharp increase in temperature and pressure, heating is likely to remain airtight and efficient. It is also important that the functionality of the heating equipment does not depend on the availability of power. Considering that wood-fired boilers are installed not in megacities, but in areas remote from the benefits of civilization, this factor will not seem so insignificant to you. Of course, this scheme is not without drawbacks, the main of which are:

The assessment should be made on the basis of understandable rules, for example, according to comparable values ​​for rooms from previous years or comparable rooms in the relevant reporting period. In this case, all heating costs are distributed according to a fixed scale, usually square meter. by experience. Calculation regulation.

What is the required boiler capacity? For example, with the help of subsequent thermal insulation ≡ Thermal insulation≡ Thermal insulation reduces heat flow from the hot to cold side of the component. For this purpose, substances with low thermal conductivity are introduced as a layer between hot and cold. An important water retention is achieved with the help of a vacuum. In addition, sleeping air retains heat flow very well.

• free access of oxygen to the system, which causes internal corrosion of pipes;
• the need to replenish the coolant level due to its evaporation;
• uneven temperature of the heat agent at the beginning and at the end of each circuit.

A layer of any mineral oil 1 - 2 cm thick poured into the expansion tank will prevent oxygen from entering the coolant and reduce the rate of evaporation of the liquid. Despite the shortcomings, the gravitational scheme is very popular due to its simplicity, reliability and low cost.

Re-evaluation is not detrimental to oil or gas condensing boilers and may even make sense in some cases. For low temperature boilers ≡ Low temperature boilers ≡ A low temperature boiler is a boiler that can also be used in continuous operation with a low heating water inlet temperature of 35 to 40 degrees Celsius and in which this can lead to condensation in the exhaust gases containing water vapor. The standard usage rate of the low temperature boiler is over 90%.

Condensing heaters achieve an even higher standard efficiency of 100%. over-measurement should be avoided. To ensure the safe removal of exhaust gases from the heating system, the heating and the chimney must match each other. Previously, the interaction between the boiler and the chimney was much less important. The adaptation of the chimney to the boiler was in the background. The high flue gas temperatures of the boilers at that time also ensured that the flue gases were discharged without damage, even in the case of large chimney cross-sections, and the chimney was dry.

When deciding to install in this way, please note that for normal circulation of the coolant, the boiler inlet must be at least 0.5 m below the heating radiators. The supply and return pipes must have slopes for normal circulation of the coolant. In addition, it is important to correctly calculate the hydrodynamic resistance of all branches of the system, and in the design process, try to reduce the number of shut-off and control valves. The correct operation of the system with natural circulation of the coolant also depends on the installation location of the expansion tank - it must be connected at the highest point.

However, the exhaust gases of modern low-temperature and condensing boilers have very low temperatures due to energy-saving operation. In addition, when replacing an old boiler, the nominal heat output of the boiler is adapted to the actual, possibly reduced heat load of the building. This usually results in reduced performance compared to an older boiler with big size. Due to the existing chimney, significantly lower exhaust gas volumes with lower exhaust gas temperatures will be transferred after the replacement of the old boiler.

Closed system with natural circulation

Installing a membrane-type expansion tank on the return line will avoid the harmful effects of oxygen and eliminate the need to control the level of the coolant. When deciding to equip the gravity system with a hermetic expansion tank, consider the following points:

Why are chimneys damp? The hot exhaust gas that exits the combustion chamber of the boiler contains water vapor. If this exhaust gas is cooled to a certain temperature, water vapor becomes water and is deposited on cooler surfaces. The temperature of the flue gases in the humidified chimneys must be high enough to prevent condensation in the chimney, otherwise this could lead to moisture penetration or.

The relevant standards and building codes require precise coordination of the exhaust system with the heat source. The chimney must be planned and constructed in such a way that exhaust gases can be removed without mechanical assistance and that damage to the chimney or the building is avoided.

• the capacity of the membrane tank must contain at least 10% of the volume of the entire coolant;
• a safety valve must be installed on the supply pipe;
• the highest point of the system must be equipped with an air vent.

Additional devices that are included in the boiler safety group (safety valve and air vent) will have to be purchased separately - manufacturers very rarely complete units with such devices. The safety valve allows the coolant to be discharged if the pressure in the system exceeds a critical value. The normal working indicator is considered to be a pressure from 1.5 to 2 atm. The emergency valve is set to 3 atm.

The following requirements for the flue system must be observed. If the chimney is located on an outside wall, there is a risk that the exhaust gas will not get the necessary thermal buoyancy and that water vapor will condense on the chimney walls. In many cases, the existing chimney will be replaced by the aforementioned chimney. no longer meet the requirements.

Every year the chimney cleaner confirms good values exhaust gases. "What else do you need?", you may wonder. "A whole lot" is our answer. More energy and save more money for the environment, more comfort, more operational security, learn more to trust the future security. The deflection of the chimney determines whether the quality of combustion and the loss of exhaust gases during burner operation comply with legal requirements. He checks if the pipe is working and the system is safe.

Features of systems with forced movement of the coolant

In order to equalize the temperature in all areas, a circulation pump is integrated into a closed heating system. Since this unit can provide forced movement of the coolant, the requirements for the installation level of the boiler and compliance with slopes become negligible. However, you should not give up the autonomy of natural heating. If a bypass branch called a bypass is installed at the outlet of the boiler, then in the event of a power outage, the circulation of the heating agent will be provided by gravity forces.

Even if he reassures you of ideal values, it doesn't make much difference to the economy of your system. After all, the old boiler has to work constantly with a high temperature. all year round. Especially during the transitional months or even in summer when the boiler is only needed for heating drinking water, high cooling and/or heat is generated, which is generally much higher than the flue gas loss measured as it passes through the chimney.

Not so with a new boiler. Here, the boiler water temperature is automatically adjusted to the corresponding temperature. outdoor temperature. If heat is not required, they will even turn off completely. If the boiler is 10 years old or more, then it is worth dealing with a new heating system. The new system saves up to 30% of energy and costs. You have a clear plus in comfort, work safety, environmental protection and safety in order to further comply with legal requirements.

The electric pump is installed on the return line, between the expansion tank and the inlet fitting. Due to the low temperature of the coolant, the pump operates in a more gentle mode, which increases its durability. The installation of a circulation unit on the return is also necessary for safety reasons. When water boils in the boiler, the formation of steam is possible, the entry of which into the centrifugal pump is fraught with a complete cessation of the movement of the liquid, which can lead to an accident. If the device is installed at the inlet to the heat generator, then it will be able to circulate the coolant even in the event of emergency situations.

Operational safety: Heating is required only when required

Of course, it would be exaggerated to think that your old system heating will give up his spirit in the coming days with a big blow. No, if she does, she will probably do it quietly and calmly - without warning. In any case, you can show new materials and features without any obligation in our showrooms.

Operating costs: is this what he wants?

you will notice high efficiency and a long boiler life that is easy to maintain. How much is your oil and gas worth, check your bill regularly. It is not easy to see if your heating system is economically viable. Perhaps it even generates heat where no one is needed: Or it's just oversized.

Connection via manifolds

If it is required to connect several parallel branches with radiators, a water heated floor, etc. to a solid fuel boiler, then balancing the circuits is required, otherwise the coolant will follow the path of least resistance, and the rest of the system will remain cold. For this purpose, one or more collectors (combs) are installed at the outlet of the heating unit - distribution devices with one input and several outputs. Installation of combs opens up wide opportunities for connecting several circulation pumps, allows you to supply a heat agent of the same temperature to consumers and regulate its supply. The only disadvantage of this type of strapping can be considered a complication of the design and an increase in the cost of the heating system.

The development of harmful exhaust gases is closely related to consumption and use. Boilers that consume a lot also produce a lot of exhaust gases. Key words: forest death, greenhouse effect. Old boilers consume about a third of the fuel and produce more than 60 percent of pollutants than new boilers.

New burners with modern technology have particularly economical combustion with favorable values, so that they still do not meet the requirements of the Blue Angel environmental label and the Swiss Air Pollution Regulation.

A separate case of collector piping is a connection with a hydraulic arrow. Its difference from a conventional collector lies in the fact that this device acts as a kind of intermediary between the heating boiler and consumers. Made in the form of a pipe large diameter, the hydraulic arrow is installed vertically and connected to the inlet and pressure pipes of the boiler. At the same time, the insertion of consumers is done at different heights, which allows you to choose the optimal temperature for each circuit.

Operational safety, cost, Environment, ease of use. You may be thinking: “Yes, such a modern heater that I already liked.” And you might also think: But it's worth it again. After all, it's not just about buying the purchase price. Then the account looks completely different.

Then you could say, "I can't put off that much." Be sure to have this account set up for your home by a specialist. He also knows funding, for example, for solar and condensing technology. What is a return? Where and why is the technology used? How is backflow increased? What are the benefits of an efficient heating system?

Installation of emergency and control systems

Alarm and control systems serve several purposes:

• protection of the system from depressurization in the event of an uncontrolled increase in pressure;
• temperature control of individual circuits;
• protection of the boiler against overheating;
• prevention of condensation processes associated with a large difference in supply and return temperatures.

To solve the problems of system safety, a safety valve, an emergency heat exchanger or a natural circulation circuit are introduced into the piping scheme. As for the issues of regulating the temperature of the heat agent, thermostatic and controlled valves are used for this purpose.

Modern heating systems only work optimally when certain operating temperatures are not exceeded or exceeded. To prevent excessive cooling of the return, use a so-called return lift. We explain to you in this article what it is with a rollback and how to implement it technically. You will also find out which heating systems have a reverse rise and which do not.

Free 5 suggestions for your new heater inquiry

Functional implementation of backflow lifting

Reverse lift is a technology used in hot water heating systems to quickly achieve and maintain the desired minimum temperature in the heating circuit heater. The rise of the return flow is achieved through the use of a special mixing valve. It mixes under the cold return a variable part of the hot heating water that has been heated by the heat source. This results in a generally faster and higher temperature of the heating medium returning back to the heat generator.

Trim with a three-way valve.

Solid fuel boiler is a heating unit periodical action, therefore, it is in danger of corrosion due to condensate that falls on its walls during heating. This is due to the ingress of too cold coolant from the return into the heat exchanger of the heating unit. The danger of this factor can be eliminated with the help of a three-way valve. This device is an adjustable valve with two inlets and one outlet. On a signal from the temperature sensor, the three-way valve opens the hot coolant supply channel to the boiler inlet, preventing the occurrence of a dew point. Once heating unit enters the operating mode, the liquid supply in a small circle stops.

Therefore, in the heat exchanger flow and return flow with a lower temperature difference. The higher temperature of the return flow, which rises in this way, has a positive effect on the operation of the heating system, which can thus function optimally. The optimum operating temperature depends on the fuel being burned, more precisely on the so-called flue gas dew point.

At the same time, back-up lift is used to counteract damage that can occur, for example, when gases that accumulate during fuel combustion are heated to cool and condense. Condensation can damage the system because it causes effects such as pitting. Temperature differences can also cause stress leading to cracking.

A fairly common mistake is to install a centrifugal pump before a three-way valve. Naturally, with the valve closed, there can be no question of any circulation of fluid in the system. It will be correct to install the pump after the adjusting device. The three-way valve can also be used to control the temperature of the heating agent supplied to the consumers. In this case, the device is set to work in the other direction, mixing cold coolant from the return to the supply.

Scheme with buffer capacity

The low controllability of solid fuel boilers requires constant monitoring of the amount of firewood and draft, which significantly reduces the convenience of their operation. To load more fuel and at the same time not to worry about the possible boiling of the liquid will allow the installation of a buffer tank (heat accumulator). This device is a sealed tank that separates the heating unit from consumers. Due to the large volume, the buffer tank can accumulate excess heat and release it to radiators as needed. The mixing unit, which uses the same three-way valve, will help to adjust the temperature of the liquid coming from the heat accumulator.

Strapping elements that ensure the safety of the heating system

Except safety valve, which was mentioned above, the protection of the heating unit from overheating is solved using an emergency circuit, through which cold water is supplied to the heat exchanger from the water supply. Depending on the design of the boiler, the coolant can be supplied directly to the heat exchanger or a special coil installed in the working chamber of the unit. By the way, it is the latter option that is the only possible one for systems filled with antifreeze. Water supply is carried out using a three-way valve, which is controlled by a sensor installed inside the heat exchanger. The discharge of the "waste" liquid occurs through a special line connected to the sewer.

Scheme with connecting an indirect heating boiler

The piping with the connection of a boiler for hot water supply can be used for heating systems of all types. To do this, a special heat-insulated container (boiler) is connected to the water supply and DHW system, and a coil is installed inside the water heater, which is cut into the heating agent supply line. Passing along this circuit, the hot coolant gives off heat to the water. Often, an indirect heating boiler is also equipped with heating elements, thanks to which it becomes possible to receive hot water in the warm season.

Proper installation of a solid fuel boiler in a closed-type heating system

A huge advantage of solid fuel boilers is that no permits are required for their installation. Installation is quite possible to carry out with your own hands, especially since this does not require any special tools or special knowledge. The main thing is to approach the work responsibly and observe the sequence of all stages.

Boiler room arrangement. The disadvantage of heating units used for burning wood and coal is the need for a special, well-ventilated room. Of course, it would be possible to install a boiler in the kitchen or bathroom, however, the periodic emission of smoke and soot, dirt from fuel and combustion products make this idea unsuitable for implementation. In addition, the installation of burning equipment in living rooms is also unsafe - the release of fumes can lead to tragedy. When installing a heat generator in a boiler room, several rules are observed:

• the distance from the furnace door to the wall must be at least 1 m;
• ventilation ducts must be installed at a distance not higher than 50 cm from the floor and not lower than 40 cm from the ceiling;
• the room should not contain fuel, lubricants and flammable substances and objects;
• the base platform in front of the ash pan is protected with a metal sheet measuring at least 0.5x0.7 m.

In addition, at the installation site of the boiler, an opening is provided for the chimney, which is brought out. Manufacturers indicate the configuration and dimensions of the chimney in technical passport, so there is no need to invent anything. Of course, if the need arises, then the requirements of the documentation can be deviated, however, in any case, the channel for the removal of combustion products should provide excellent traction in any weather. When installing a chimney, all joints and cracks are sealed with sealing materials, and windows are also provided for cleaning the channels from soot and a condensate trap.

Preparing to install the heating unit

Before installing the boiler, choose a piping scheme, calculate the length and diameter of the pipelines, the number of radiators, the type and number additional equipment and shutoff and control valves. Despite all the variety of design solutions, experts recommend choosing combined heating, which can provide forced and natural circulation of the coolant. Therefore, when calculating, it is necessary to consider how a parallel section of the supply pipeline (bypass) with a centrifugal pump will be installed and provide for the slopes necessary for the operation of the gravity system. Do not give up on the buffer capacity. Of course, its installation will entail additional expenses. However, this type of accumulator will be able to even out the temperature curve, and one bookmark of fuel will last for a longer time.

A solid fuel boiler with an additional circuit, which is used for hot water supply, will provide special comfort. Given the fact that due to the installation of a solid fuel unit in a separate room, the length of the DHW circuit increases significantly, an additional circulation pump is mounted on it. This will eliminate the need to drain cold water while waiting for hot water to come out. Before installing the boiler, it is imperative to provide a place for the expansion tank and do not forget about devices designed to reduce pressure in the system in critical situations. simple circuit strapping, which can be used as a working draft, is shown in our figure. It integrates all the equipment discussed above and ensures its correct and trouble-free operation.

Installation and connection of a solid fuel heat generator

After carrying out all the necessary calculations and preparation of equipment and materials, installation begins.

• Install in place, level and fix the heating unit, after which a chimney is connected to it.

• They fix heating radiators, install a heat accumulator and an expansion tank.

• Mount the supply pipeline and bypass, on which the circulation pump is installed. On both sections (straight and bypass) install Ball Valves so that the coolant can be transported by forced or natural way. We remind you that a centrifugal pump can only be installed with the correct orientation of the shaft, which must be in a horizontal plane. The manufacturer indicates the schemes of all possible mounting options in the instructions for the product.

• The pressure line is connected to a heat accumulator. I must say that both the inlet and outlet pipes of the buffer tank must be installed in its upper part. Due to this, the number warm water in the tank will not affect the readiness of the heating circuit. Be sure to note the fact that the cooling of the boiler during the reboot period will reduce the temperature in the system. This is due to the fact that at this time the heat generator will work as an air heat exchanger, transferring heat from the heating system to the chimney. To eliminate this shortcoming, separate circulation pumps are installed in the boiler and heating circuits. By placing a thermocouple in the combustion zone, it is possible to stop the movement of the coolant through the boiler circuit when the fire is extinguished.

• A safety valve and an air vent are installed on the supply line.

• They connect the emergency circuit of the boiler or install shut-off and control valves, which, when the water boils, will open the line for its discharge into the sewer and the channel for supplying cold liquid from the water supply.

• Mount the return pipeline from the heat accumulator to the heating unit. Before the inlet pipe of the boiler, a circulation pump, a three-way valve and a sump filter are installed.

• Separately, an expansion tank is mounted on the return pipeline. Note! On pipelines that are connected to protection devices, stop valves are not installed. These areas should have as few connections as possible.

• The upper outlet of the heat storage tank is connected to a three-way valve and circulation pump heating circuit, after which the radiators are connected and the return pipeline is mounted.

• After connecting the main circuits, they begin to equip the hot water supply system. If the heat exchanger coil is built into the boiler, then it will be enough just to connect the cold water inlet and the outlet to the “hot” main to the corresponding pipes. When installing a separate indirect water heater, a circuit with an additional circulation pump or a three-way valve is used. In both cases, a check valve is installed at the cold water inlet. It will block the path for the heated liquid to the "cold" water supply.

• Some solid fuel boilers are equipped with a draft regulator, the work of which is to reduce the flow area of ​​the blower. Due to this, the air flow into the combustion zone is reduced and its intensity, and, accordingly, the temperature of the coolant decreases. If the heating unit has such a design, then they mount and adjust the drive of the air damper mechanism.

All threaded connections must be carefully sealed with sanitary flax and a special non-drying paste. After the installation is completed, the coolant is poured into the system, the centrifugal pumps are turned on at full capacity and the places of all connections are carefully inspected for leakage. After making sure that there are no leaks, they kindle the boiler and check the operation of all circuits at maximum modes.

Features of the integration of a solid fuel unit into an open heating system

The main feature of open heating systems is the contact of the coolant with atmospheric air, which occurs with the participation of an expansion tank. This capacity is designed to compensate for the thermal expansion of the coolant, which occurs when it is heated. The expander is cut in at the highest point of the system, and in order to prevent hot liquid from flooding the room when the tank overflows, a drain pipe is connected to its upper part, the second end of which is led into the sewer.

The large volume of the tank forces it to be installed in the attic, so additional insulation of the expander and the pipes suitable for it will be required, otherwise they may freeze in winter. In addition, it must be remembered that this element is part of the heating system, so its heat loss will lead to a decrease in temperature in the radiators. Since the open system is not hermetic, there is no need to install a safety valve and connect emergency circuits. When the coolant boils, the pressure will be released through the expansion tank.

Special attention should be paid to pipelines. Since the water in them will flow by gravity, the circulation will be influenced by the diameter of the pipes and the hydraulic resistance in the system. The last factor depends on turns, narrowings, level drops, etc., so their number should be minimal. In order to initially give the water flow the necessary potential energy, a vertical riser is mounted at the outlet of the boiler. The higher the water can rise along it, the higher the coolant speed will be and the faster the radiators will warm up. For the same purpose, the return inlet must be located at the lowest point of the heating system.

Finally, I would like to note that in open systems it is preferable to use not antifreeze, but water. This is due to a higher viscosity, reduced heat capacity and rapid aging of the substance upon contact with air. As for water, it is best to soften it and, if possible, never drain it. This will increase the service life of pipelines, radiators, heat generators and other heating equipment several times.

Solid fuel boiler piping - Emergency cooling valve

3. Protection against low temperature of the coolant in the "return" of the solid fuel boiler.

What will happen to a solid fuel boiler if its “return” temperature is below 50 °C? The answer is simple - a resinous coating will appear on the entire surface of the heat exchanger. This phenomenon will reduce the performance of your boiler, make it much more difficult to clean and, most importantly, can lead to chemical damage to the walls of the boiler heat exchanger. To prevent such a problem, it is necessary to provide appropriate equipment when installing a heating system with a solid fuel boiler.

The task is to ensure the temperature of the coolant that returns to the boiler from the heating system at a level not lower than 50 °C. It is at this temperature that the water vapor contained in the flue gases of a solid fuel boiler begins to condense on the walls of the heat exchanger (transition from a gaseous state to a liquid one). The transition temperature is called the "dew point". The condensation temperature directly depends on the moisture content of the fuel and the amount of hydrogen and sulfur formations in the combustion products. As a result of a chemical reaction, iron sulfate is obtained - a substance useful in many industries, but not in a solid fuel boiler. Therefore, it is quite natural that manufacturers of many solid fuel boilers remove the boiler from the guarantee in the absence of a return water heating system. After all, here we are not dealing with the burning of metal at high temperatures, but with chemical reactions, under which no boiler steel can withstand.

The simplest solution to the low return temperature problem is to use a thermal three-way valve (anti-condensation thermostatic mixing valve) . The thermal anti-condensation valve is a thermomechanical three-way valve that ensures the admixture of the coolant between the primary (boiler) circuit and the coolant from the heating system in order to achieve a fixed temperature of the boiler water. In fact, the valve lets the unheated coolant through a small circle and the boiler heats itself. After reaching the set temperature, the valve automatically opens the access of the coolant to the heating system and works until the return temperature drops below the set values ​​again.

Solid fuel boiler piping - Anti-condensation valve

4. Protection of the heating system of a solid fuel boiler from operation without a coolant.

The operation of the boiler without a coolant is strictly prohibited by all manufacturers of solid fuel boilers. Moreover, the coolant in the heating system must always be under a certain pressure, which depends on your heating system. When the pressure in the system drops, the user opens the valve and fills the system up to a certain pressure.

In this case, there is a "human factor", which may well make mistakes. You can solve this issue with the help of automation.
Automatic make-up installation - a device that is adjusted to a certain pressure and connected to an open water tap. In the event of a pressure drop, the process of filling the system to the desired pressure will occur fully automatically.

In order for everything to work correctly, it is necessary to fulfill certain conditions when installing the automatic make-up valve:
- it is necessary to mount the automatic make-up valve at the lowest point of the heating system;
- during installation, it is imperative to leave access for cleaning or possible replacement of the valve;
- water from the water supply must be constantly supplied to the valve with pressure, and the water supply tap and the make-up valve must always be open.

Solid fuel boiler piping - Automatic make-up valve

5. Removal of air from the heating system of the solid fuel boiler.

Air in the heating system can cause a number of problems: poor circulation of the coolant or its absence, noise during pump operation, corrosion of radiators or elements of the heating system. To avoid this, it is necessary to bleed air from the system. There are two ways for this - the first manually - we think over the installation of cranes in highest point systems and on lifting sections and periodically pass these taps, releasing air. The second way is to install an automatic air release valve. The principle of its operation is simple - when there is no air in the system, the valve is filled with water and the float is located at the top of the valve, and, through a hinged lever, seals the air outlet valve.

When air enters the valve chamber, the water level in the valve drops, the float moves down and through the articulated arm opens the air outlet on the outlet valve. As air escapes from the chamber, the water level rises and the valve returns to its upper position.

We have already described the device of the boiler safety group above when we talked about protection against high coolant pressure. Ideally, if you have installed a safety group, it has an automatic air release valve. Just make sure that the safety group is installed at the top of your heating system. If not, we recommend installing a separate automatic air release valve and permanently solve the problem of finding air pockets in your heating system.

Solid fuel boiler piping - Automatic air release valve