What is the optimum temperature for a gas boiler. Optimal operation of the heating boiler

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 depends 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 systems heating, 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 efficient operation of 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 - the type of heating system, the number of circuits, the presence of additional energy consumers, etc. The piping 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 regulation can also be carried out using these heating systems in principle, but is usually associated with much higher costs. Precise definition characteristics of the heating system boiler is possible only if the heat loss of the 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.

Open type system with natural circulation in a private house First of all, it should be noted that open systems of the gravity type 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.

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 provide safe removal exhaust gases from the heating system, heating and 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 rated 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 a larger 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 exhaust gas values. "What else do you need?", you may wonder. "A whole lot" is our answer. More energy and save more 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 assures you of ideal values, it does not of great importance for 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 the summer, when the boiler is only needed to heat drinking water, high cooling and/or heat is generated, which is generally much higher than the flue gas losses measured when passing 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. New system saves up to 30% 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 heating system will give up its 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 the high efficiency and long life of the boiler which 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 - switchgears with one input and multiple 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.

The new burners with state-of-the-art technology have particularly economical combustion with favorable values, so 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 large diameter pipe, 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 temperature difference between the supply and return.

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 heating systems hot water 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. This mixes under the cold return a variable portion of the hot heating water, which was heated by a heat generator. 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.

A solid fuel boiler is a heating unit of periodic operation, therefore it is at risk 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. As soon as the 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 positive influence to the operation of the heating system, so that it can 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

In addition to the safety valve mentioned above, the protection of the heating unit against 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 working chamber 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 the hot water supply 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.

Correct installation solid fuel boiler in a closed heating system

A huge advantage of solid fuel boilers is that their installation does not require any permits. Installation can be done by hand, especially since this does not require any special tool, no 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 incineration equipment in living rooms it 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. Installing chimney, all joints and gaps are sealed with sealing materials, and windows are also provided for cleaning channels from soot and a condensate trap.

Preparing to install the heating unit

Before installing the boiler, a piping scheme is selected, the length and diameter of pipelines, the number of radiators, the type and number of additional equipment and shut-off and control valves are calculated. 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 costs. 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. In both sections (direct and bypass), ball valves are installed so that the coolant can be transported by forced or natural means. 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. As a result, the amount of hot 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 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 a heating circuit circulation pump, after which radiators are connected and a 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 inlet to the corresponding pipes for cold water and access to the "hot" highway. 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.

The places of all threaded connections must be carefully sealed with sanitary flax and a special non-drying paste. After installation is completed, the coolant is poured into the system, turned on at full power centrifugal pumps and carefully inspect all connections for leaks. 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 you will need additional insulation expander and the pipes that fit it, 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 in 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 state). 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 that 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. Can be solved this question using 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.

For everything to work correctly, some conditions must be met 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 necessary to leave access for cleaning or possible replacement 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.

The 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 one manually - we think over the installation of cranes at the highest point of the system and on the lifting sections and periodically pass these cranes, 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

The efficiency of the heating system depends on many factors. These include the rated power, the degree of heat transfer of radiators and the temperature regime of operation. For the latter indicator, it is important to choose the right degree of heating of the coolant. Therefore, it is necessary to determine the optimal temperature in the heating system for water, radiators and the boiler.

What determines the temperature of the water in the heating

For the correct operation of the heat supply, a graph of the temperature of the water in the heating system is necessary. According to it, the optimal degree of heating of the coolant is determined depending on the influence of various external factors. It can be used to determine what water temperature in the heating batteries should be in a certain period of time the system is running.

It is a common misconception that the higher the degree of heating of the coolant, the better. However, this increases fuel consumption, increasing operating costs.

Often, the low temperature of the radiators is not a violation of the norms for heating the room. A low-temperature heat supply system was simply designed. That is why the exact calculation of water heating should be given Special attention.

The optimum water temperature in the heating pipes largely depends on external factors. To determine it, the following parameters must be taken into account:

• Heat loss at home. They are decisive for the calculation of any type of heat supply. Their calculation will be the first stage in the design of heat supply;
• Boiler characteristics. If the operation of this component does not meet the design requirements, the water temperature in the heating system of a private house will not rise to the desired level;
• Material for the manufacture of pipes and radiators. In the first case, it is necessary to use pipes with a minimum thermal conductivity. This will reduce heat losses in the system during the transportation of the coolant from the boiler heat exchanger to the radiators. For batteries, the opposite is important - high thermal conductivity. Therefore, the temperature of the water in the radiators central heating, made of cast iron, should be slightly higher than that of aluminum or bimetallic structures.

Is it possible to independently determine what temperature should be in the radiators? It depends on the characteristics of the system components. To do this, you should familiarize yourself with the properties of the batteries, the boiler and the heat supply pipes.

In a centralized heating system, the temperature of the heating pipes in the apartment is not important indicator. It is important that the norms for heating air in living rooms are observed.

Heating standards in apartments and houses

In fact, the degree of water heating in pipes and heat supply radiators is a subjective indicator. It is much more important to know the heat dissipation of the system. It, in turn, depends on the minimum and Maximum temperature water in the heating system can be reached during operation.

For autonomous heat supply, the norms of central heating are quite applicable. They are detailed in the resolution of the PRF No. 354. It is noteworthy that the minimum water temperature in the heating system is not indicated there.

It is only important to observe the degree of heating of the air in the room. Therefore, in principle, the temperature regime of operation of one system can be different from another. It all depends on the influencing factors that were mentioned above.

In order to determine what temperature should be in the heating pipes, you should familiarize yourself with the current standards. In their content there is a division into residential and non-residential premises, as well as the dependence of the degree of air heating on the time of day:

• In rooms during the daytime. In this case, the standard heating temperature in the apartment should be +18°C for rooms in the middle of the house and +20°C in the corners;
• In living rooms at night. Some reduction is allowed. But at the same time, the temperature of the heating radiators in the apartment should provide, respectively, + 15 ° С and + 17 ° С.

Responsible for compliance with these standards Management Company. In case of their violation, you can request a recalculation of payment for heating services. For autonomous heat supply, a table of temperatures for heating is made, where the values ​​\u200b\u200bof the heating of the coolant and the degree of load on the system are entered. At the same time, no one bears responsibility for violation of this schedule. This will affect the comfort of staying in a private house.

For centralized heating, it is mandatory to maintain the required level of air heating in stairwells and non-residential premises. The temperature of the water in the radiators must be such that the air is heated to minimum value+12°С.

Calculation of the temperature regime of heating

When calculating the heat supply, the properties of all components must be taken into account. This is especially true for radiators. What is the optimal temperature in the radiators - + 70 ° C or + 95 ° C? It all depends on thermal calculation which is carried out at the design stage.

First you need to determine the heat loss in the building. Based on the data obtained, a boiler with the appropriate power is selected. Then comes the most difficult design stage - determining the parameters of heat supply batteries.

They must have a certain level of heat transfer, which will affect the temperature curve of the water in the heating system. Manufacturers indicate this parameter, but only for a certain mode of operation of the system.

If you need to spend 2 kW of thermal energy to maintain a comfortable level of air heating in a room, then the radiators must have no less heat transfer.

To determine this, you need to know the following quantities:

• Permissible maximum water temperature in the heating system -t1. It depends on the power of the boiler, temperature limit impact on pipes (especially polymer);
• Optimal the temperature that should be in the heating return pipes - t This is determined by the type of wiring of the mains (one-pipe or two-pipe) and the total length of the system;
• Required degree of air heating in the room -t.

Tnap=(t1-t2)*((t1-t2)/2-t3)

Q=k*F*Tnap

Where k- heat transfer coefficient of the heating device. This parameter must be specified in the passport; F- radiator area; Tnap- thermal pressure.

By varying the various indicators of the maximum and minimum water temperatures in the heating system, you can determine the optimal mode of operation of the system. It is important to correctly initially calculate the required power heater. Most often, the indicator of low temperature in heating batteries is associated with heating design errors. Experts recommend adding a small margin to the obtained value of the radiator power - about 5%. This will be needed in case of a critical decrease in the temperature outside in the winter.

Most manufacturers indicate the heat output of radiators according to the accepted standards EN 442 for mode 75/65/20. This corresponds to the norm of the heating temperature in the apartment.

Water temperature in the boiler and heating pipes

After performing the above calculation, it is necessary to adapt the heating temperature table for the boiler and pipes. During the operation of heat supply, emergency situations should not occur, a frequent cause of which is a violation of the temperature schedule.

The normal indicator of water temperature in central heating batteries can be up to + 90 ° С. This is strictly monitored at the stage of preparation of the coolant, its transportation and distribution to residential apartments.

The situation with autonomous heat supply is much more complicated. In this case, control completely depends on the owner of the house. It is important to ensure that there is no excess of water temperature in the heating pipes that goes beyond the schedule. This may affect the security of the system.

If the water temperature in the heating system of a private house exceeds the norm, the following situations may occur:

• Pipeline damage. In particular, this applies to polymer lines, in which the maximum heating can be + 85 ° C. That is why the normal value of the temperature of the heating pipes in an apartment is usually + 70 ° C. Otherwise, deformation of the line may occur and a rush will occur;
• Air heating excess. If the temperature of the heat supply radiators in the apartment provokes an increase in the degree of air heating above + 27 ° C - this is beyond the normal range;
• Reduced service life of heating components. This applies to both radiators and pipes. Over time, the maximum temperature of the water in the heating system will lead to breakdown.

Also, a violation of the water temperature schedule in the autonomous heating system provokes the formation air locks. This occurs due to the transition of the coolant from a liquid state to a gaseous state. Additionally, this affects the formation of corrosion on the surface of the metal components of the system. That is why it is necessary to accurately calculate what temperature should be in the heat supply batteries, taking into account their material of manufacture.

The most common violation thermal regime work is observed in solid fuel boilers. This is due to the problem of adjusting their power. When a critical temperature level in the heating pipes is reached, it is difficult to quickly reduce the boiler power.

The influence of temperature on the properties of the coolant

In addition to the above factors, the temperature of the water in the heat supply pipes affects its properties. This is the principle of operation of gravitational heating systems. With an increase in the level of heating of water, it expands and circulation occurs.

However, in the case of using antifreezes, the excess temperature in the radiators can lead to other results. Therefore, for heat supply with a coolant other than water, you must first find out the permissible indicators of its heating. This does not apply to the temperature of the radiators. district heating in the apartment, since antifreeze-based liquids are not used in such systems.

Antifreeze is used if there is a possibility of low temperature affecting the radiators. Unlike water, it does not begin to change from a liquid to a crystalline state when it reaches 0°C. However, if the work of heat supply is outside the norms of the temperature table for heating in big side- The following events may occur:

• Foaming. This entails an increase in the volume of the coolant and, as a consequence, an increase in pressure. The reverse process will not be observed when the antifreeze cools;
• Formation of limescale. The composition of antifreeze includes a certain amount of mineral components. If the norm of the heating temperature in the apartment is violated in a big way, their precipitation begins. Over time, this will lead to clogging of pipes and radiators;
• Increasing the density index. There may be malfunctions in the operation of the circulation pump if its rated power was not designed for the occurrence of such situations.

Therefore, it is much easier to monitor the temperature of the water in the heating system of a private house than to control the degree of heating of antifreeze. In addition, ethylene glycol-based compounds emit a gas harmful to humans during evaporation. Currently, they are practically not used as a coolant in autonomous systems heat supply.

Before pouring antifreeze into the heating, replace all rubber gaskets to paranitic. It's connected with increased rate permeability of this type of coolant.

Ways to normalize the temperature regime of heating

The minimum value of the water temperature in the heating system is not main threat for her work. This, of course, affects the microclimate in residential premises, but in no way affects the functioning of heat supply. In case of excess of norm of heating of water there can be emergencies.

When drawing up a heating scheme, it is necessary to provide for a number of measures aimed at eliminating a critical increase in water temperature. First of all, this will lead to an increase in pressure and an increase in the load on the inner surface of pipes and radiators.

If this phenomenon is one-time and short-lived, the heat supply components may not be affected. However, such situations arise under the constant influence of certain factors. Most often, this is the incorrect operation of a solid fuel boiler.

• Installing a security group. It consists of an air vent, a bleed valve and a pressure gauge. If the water temperature reaches a critical level, these components will remove excess coolant, thereby ensuring the normal circulation of the liquid for its natural cooling;
• mixing unit. It connects the return and supply pipes. Additionally, a two-way valve with a servo drive is installed. The latter is connected to a temperature sensor. If the value of the degree of heating exceeds the norm, the valve will open and the flows of hot and cooled water will mix;
• Electronic heating control unit. It records the temperature of the water in various parts of the system. In case of violation of the thermal regime, he will give the appropriate command to the boiler processor to reduce power.

These measures will help prevent incorrect operation of the heating for another initial stage the occurrence of a problem. The most difficult thing is to regulate the level of water temperature in systems with a solid fuel boiler. Therefore, for them, special attention should be paid to the choice of parameters of the safety group and the mixing unit.

The effect of water temperature on its circulation in heating is described in detail in the video:

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, oxidized, forms aggressive sulfuric anhydride, which, dissolving in water, forms a film of sulfuric acid solution on the heating surfaces, as a result, the corrosion process sharply intensifies. 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, in most cases, the temperature of the water entering the economizer exceeds the required temperature because the water comes from atmospheric deaerators 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 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.

A heating boiler is a device that, by means of the combustion of fuel (or electricity), heats the coolant.

The device (design) of the heating boiler: heat exchanger, thermally insulated housing, hydraulic unit, as well as safety elements and automation for control and monitoring. For gas and diesel boilers, a burner is provided in the design, for solid fuel boilers - a firebox for firewood or coal. Such boilers require a chimney connection to remove combustion products. Electric boilers are equipped with heating elements, do not have burners and a chimney. Many modern boilers are equipped with built-in pumps for forced circulation of water.

The principle of operation of the heating boiler- the coolant, passing through the heat exchanger, heats up and then circulates through the heating system, giving the received thermal energy through radiators, underfloor heating, heated towel rails, as well as providing water heating in an indirect heating boiler (if it is connected to the boiler).

Heat exchanger - metal container, in which the coolant (water or antifreeze) is heated - can be made of steel, cast iron, copper, etc. Cast iron heat exchangers are resistant to corrosion and quite durable, but sensitive to sharp drop temperatures and are heavy. Steel can suffer from rust, so their internal surfaces are protected by various anti-corrosion coatings to increase their service life. Such heat exchangers are the most common in the manufacture of boilers. Corrosion is not terrible for copper heat exchangers and thanks to high coefficient heat transfer, low weight and dimensions, such heat exchangers are popular, often used in wall-mounted boilers, but usually more expensive than steel ones.
In addition to the heat exchanger, an important part of gas or liquid fuel boilers is a burner, which can be various kinds: atmospheric or fan, single-stage or two-stage, with smooth modulation, double. ( Detailed description burners are presented in articles about gas and liquid fuel boilers).

To control the boiler, automation is used with various settings and functions (for example, a weather-dependent control system), as well as devices for remote control of the boiler - a GSM module (controlling the operation of the device via SMS messages).

Main technical specifications heating boilers are: boiler power, type of energy carrier, number of heating circuits, type of combustion chamber, type of burner, type of installation, pump availability, expansion tank, boiler automation, etc.

To determine required power heating boiler for a house or apartment, a simple formula is used - 1 kW of boiler power for heating 10 m 2 of a well-insulated room with a ceiling height of up to 3 m. Accordingly, if heating of a glazed basement is required winter garden, rooms with non-standard ceilings, etc. boiler output must be increased. It is also necessary to increase the power (about 20-50%) while providing the boiler with hot water (especially if heating the water in the pool is necessary).

Note the feature of calculating the power of gas boilers: nominal pressure gas, at which the boiler operates at 100% of the capacity declared by the manufacturer, for most boilers is from 13 to 20 mbar, and the actual pressure in gas networks in Russia can be 10 mbar, and sometimes even lower. Accordingly, a gas boiler often works only at 2/3 of its capacity, and this must be taken into account when calculating. When choosing the power of the boiler, be sure to note all the features of the thermal insulation of the house and premises. In more detail with a table for calculating the power of a heating boiler, you can

So which boiler is better to choose? Consider the types of boilers:

"Middle class"- average price, not so prestigious, but quite reliable, standard standard solutions are presented. These are Italian boilers Ariston, Hermann and Baxi, Swedish Electrolux, German Unitherm and boilers from Slovakia Protherm.

"Economy class"- budget options simple models, the service life is shorter than that of boilers of a higher category. Some manufacturers have budget models of boilers, for example,

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 of engineering systems of 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 heated premises of housing and communal and public importance 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 design features heating appliances.

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 with an excellent overheating protection system.

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 standards for the heating network.

Ways to reduce heat loss

The above information can be used to correct calculation coolant temperature standards and tell you how to determine the situation 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 will help reduce heat leakage. It will also reduce heating costs.