Despite the variety of heating equipment, a solid fuel boiler is still in great demand, especially where it is difficult to supply gas, there are difficulties in organizing the storage of liquid fuel, and power outages often occur. Consider the principle of operation and piping schemes for solid fuel boilers.
Features of the solid fuel boiler
This heating system generates heat by burning solid fuels (wood, coal, peat, pellets). It differs in its features that directly affect its effectiveness and safety:
- Inertia. The solid fuel boiler cannot be stopped immediately. After the oxygen supply is cut off, the system continues to work until the oxygen inside the furnace runs out, or until the fuel burns out. This can lead to overheating of the coolant, the formation of a large amount of steam. As a result - the destruction of the boiler body or parts of the heating system.
- Condensate. Appears when the boiler is connected directly, a coolant of low temperature passes through the boiler tank. Leads to corrosion of the steel walls of the firebox. At the same time, mixing with the ashes, it turns into a sticky mass, which is difficult to clean off.
To eliminate the listed problems, it is necessary to properly organize the boiler piping with the mandatory inclusion of a safety group in it. Let us consider in more detail why we need a piping of a solid fuel heating boiler, the main installation schemes.
Tying a solid fuel heating boiler. Appointment. Elements
The most important purpose of the piping is to ensure efficient, safe, economical operation of the boiler. This means:
- protect equipment from overheating, sudden pressure drops, maintain the most acceptable temperature;
- control the amount of coolant in the system, remove excess liquid, excess steam;
- remove air from the system;
- distribution function - to share the coolant between all heat consumers in the system.
The piping elements of a solid fuel boiler and their correct installation in one way or another work for the safety of heating equipment. The main ones include:
- safety group (pressure gauge, air vent, safety valve);
- expansion tank;
- heat accumulator;
- three-way mixing valve.
Heating boiler Tying rules that must be observed when independently connecting a solid fuel heating system:
- to avoid the appearance of condensate, the temperature difference between the supply and return should not exceed 20 ⁰С;
- protective devices should be installed that will regulate the pressure of the coolant throughout the circuit;
- it is also recommended to include in the piping automatic devices responsible for adjusting the power and temperature of the liquid in the system.
These rules work best in systems with forced coolant movement. Let's take a brief look at the piping schemes for solid fuel boilers. But before that, a few words about the safety group in the heating system.
Security group
Includes items:
- pressure gauge (shows the level of pressure in the system)
- safety valve (automatically relieves pressure if it exceeds the allowable value of 2 bar, it usually works at an indicator of 3 bar),
- automatic air vent (takes air out of the coolant).
Heating scheme It is installed on the supply pipe of the boiler itself, immediately at the outlet. It is important to remember that no locking mechanisms can be placed between the safety group and the boiler. These devices must be installed in any heating system piping scheme.
Open type with natural circulation
The simplest binding with a minimum number of devices, complete independence from electricity. The movement of fluid through the system occurs naturally due to the general arrangement of pipes at a slight slope. The boiler is installed half a meter below the level of the radiators. The minimum number of locking mechanisms, regulating devices, etc.
Such a piping is effective for a small house with a small number of heat consumers. An open-type expansion tank is installed as high as possible, in the attic, for example.
In this case, the temperature of the coolant cannot be corrected. And through an open expansion tank, air often enters, which adversely affects the inner surface of the nozzles.
Closed type with natural circulation
Also a fairly simple strapping scheme with a small number heat consumers. The scheme is very similar to the open type. It differs by the inclusion of a closed expansion tank with a membrane, which is installed on the return pipe. In addition, do not forget about the security group. Some models are already equipped with it in production.
The expansion tank is designed for a volume of more than 10% of the total volume of the coolant.
There are several important points when tying a heating boiler with polypropylene. Branch pipe from heat generator up to the safety group is made of metal, then it is laid from polypropylene. Also, the section of the return pipe with an installed three-way valve and a sensor is made of metal. Polypropylene has low thermal conductivity. If a three-way valve is installed on it, it will react with a delay to an increase in temperature, and the sensor will provide information incorrectly.
In general, the polypropylene heating boiler piping system is beneficial, quite practical.
Closed type with forced circulation
A simple circuit with a circulation pump that moves the coolant through the system. The slope as such is no longer required. The pump, as well as the temperature sensor (controls the operation of the pump) are installed on the return line (between the expansion tank and the boiler), connected to the mains.
This strapping is more productive due to the use of the device thermoregulatory. Can be used where the power supply is stable. Otherwise, when the electricity is turned off, the heating system will stop.
Collector piping with forced circulation
Circulation pump + collectors. This is a characteristic difference of the collector piping system.
The pump moves fluid through the pipes. Collectors (so-called combs) are connected to the heating system. They are pipes with a large cross section. They have one common input and several outputs for connecting the required number of heat elements (for example, radiators, a floor heating system, a heated towel rail). They are connected to the supply and return pipes of the system.
The specificity of such a connection is characterized by a separate supply of coolant to each element of the system with the same temperature and pressure. Differs in more effective regulation of work of system of heating.
It should be borne in mind that such a strapping will take a lot of time, effort, material costs (high pipe consumption, financial expenses).
Harness with hydraulic gun
The strapping system uses a large vertical branch pipe - hydraulic arrow. This element is connected to the boiler by supply and return pipes. It is installed in the same place as the collectors: after the expansion tank, before the heating elements (radiators, heated towel rail, etc.).
It differs from collectors in that it can be connected to a hydraulic arrow at different heights. This directly affects the temperature of the coolant, and with it, the temperature of each heating element in the house. So, using a harness with a hydraulic arrow, you can create the optimal thermal regime for each device individually.
Piping of a solid fuel boiler with heat accumulator
For equipment operating on solid fuels, it is recommended to install heat accumulator. It is a buffer tank for accumulating and then storing the heat generated by the boiler.
A very profitable device, because it allows you to increase the efficiency of solid fuel equipment, and at the same time save heating material.
The piping scheme for a solid fuel boiler with a buffer tank is as follows. Inlet and outlet pipes heat generator are connected to the heat accumulator, and from it - to the heating elements. Now two contours are formed at once:
- between heat buffer and boiler;
- between the buffer and the heaters at home.
Passing through the heating system, the coolant fills the buffer tank. At what the liquid cooled down from the heating elements passes below, at the top - hot from the boiler. The buffer accumulates heat when the furnace is operating at full capacity. After the fuel burns out, the accumulated heat from the tank is given off through the heating system for a certain time. After the storage buffer, a pump is installed, a three-way valve for adjusting the temperature of the heating fluid.
The piping scheme for a solid fuel boiler with a battery tank saves fuel, allowing you to lay coal and firewood much less often. It must be taken into account that with such a piping, the boiler power should be enough for heating and for heating the buffer tank.
Piping of a solid fuel and gas boiler (electric boiler)
This harness is relevant and in demand among residents of country houses. It allows you to organize year-round comfort in the house, including several sources of heating in the overall piping. As a rule, steam is installed from a gas heating boiler with a solid fuel device, as well as solid fuel equipment with an electric boiler.
Solid fuel boiler + electric The piping scheme for gas and electric devices with wood burning is the same, is quite simple, because it uses heat accumulator at the same time as a water gun. This allows you to efficiently supply heat to a large number of heating points at once (radiators, underfloor heating, boiler, heated towel rail, etc.). At the same time, the heat of a gas heating boiler (electric) and a wood-burning boiler charges the buffer tank, and then it supplies energy to the thermal endpoints of the heating.
There is also another option for jointly connecting a gas heating boiler (electric boiler) and solid fuel, without using a buffer tank, because it is quite expensive. Here, the main source of heating is a wood-burning boiler, gas - auxiliary.
Operating principle. After burning solid fuel, the air temperature decreases. This fixes the sensor installed in the room and immediately starts the gas boiler. The cooling main boiler switches off automatically. The gas one works until the wood-burning unit starts to work out the next portion of fuel. Now, in reverse order, the room temperature sensor switches off the gas heater.
The scheme with such a strapping is simple, you can install it yourself.
Piping with connection of an indirect water heater
The piping scheme for a solid fuel boiler with a boiler is quite common due to its cost-effectiveness and efficient operation. It is especially relevant during the heating season, when it is possible to save a significant amount on electricity.
This piping is designed in such a way that the heated liquid is supplied simultaneously to the boiler and radiators. In this case, the boiler circuit is connected to the water heater heat exchanger, which heats the water indirectly.
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Solid fuel boilers (wood, coal, peat, etc.) are usually used to heat private houses that are not connected to mains gas. The installation of such systems, due to the danger of an open combustion process, requires compliance with some simple rules that allow you to provide reliable protection against a fire.
In this article, we will describe the basic requirements for a room for a solid fuel boiler and the sequence of its connection to the heating and chimney line.
A solid fuel boiler is a heat unit with an open type combustion chamber. It is clear that the rest of the heating equipment connection scheme should be developed taking into account the requirements for open systems:
- The outlet for the combustion products of the boiler must be connected to a natural draft chimney;
- At the top of the heating circuit, it is imperative to install an expansion tank that ensures contact of the coolant with the atmosphere;
- Such a system can only work on water.
Recently, indoor heating systems have become much more popular among owners of suburban real estate. However, connecting a solid fuel boiler to closed systems is strictly prohibited. The fact is that when water is heated, there is a serious increase in its volume and pressure.
In gas models of boilers, to prevent uncontrolled expansion of the coolant, there is a thermostat that instantly turns off the burner in a dangerous situation. The combustion process in the chamber of a solid fuel boiler is much more inertial: even after a complete shutdown of the oxygen supply to the furnace (for this you also need to connect a thermostat), the water temperature in the heating circuit can rise for quite a long time. This is due to the greater heat capacity of wood compared to gas. So in case of severe overheating, excess water in an open system will simply pour out through the outlet pipe of the expansion tank. If a closed circuit is used, excessive pressure in the pipes can lead to their rupture.
Where can I install a solid fuel boiler
To accommodate boilers with an open firebox, including solid fuel ones, it is necessary to equip a separate room - a boiler room.
Most often, a place is allocated for it in the basement or on the basement floor. Unlike gas heating systems, the installation of a solid fuel boiler can be done independently, without coordination with the supervisory services. However, the installation of such equipment must be carried out in full compliance with the requirements that are given in building codes and regulations:
The main stages of installing a solid fuel boiler
The solid fuel boiler connection scheme includes the heating unit itself, heating pipes and radiators, an expansion tank, a circulation pump, a heat accumulator and automation elements: a safety and air valve, a thermostat, a pressure gauge. The installation of the boiler and the necessary connections of peripheral equipment are carried out in the following order:
After performing all these operations, you can start starting the solid fuel boiler. To do this, you need to ignite the fuel, and after 10–15 minutes, close the ignition damper. When the temperature reaches 80–85 °C, it is recommended to set the thermostat to the required level of heat supply. Now it is enough to put firewood in the firebox at the right moments, and a comfortable climate in the house will be ensured.
Recommendations for the safe and efficient use of a solid fuel boiler
Unlike gas boilers, during the operation of their solid fuel counterpart, part of the combustion products remain in the furnace. They must be periodically removed, as well as other measures to improve the efficiency of the combustion process:
Solid fuel boiler and closed heating system
As we have already noted, the installation of a conventional solid fuel boiler in a closed-type heating system is prohibited.
There are special models of boilers, the execution scheme of which provides for increased strength, resistance to high pressure and the presence of a built-in container for removing excess liquid.
Before such a boiler is approved for installation, it must pass a series of tests, which only specialists can correctly carry out. Therefore, it is not worth making a decision on the use of solid fuel thermal units in closed systems on your own, even if it is recommended by experienced installers who claim that they have already implemented more than a dozen similar solutions at other facilities.
The only possible way to combine this equipment is to use a heat exchanger, which allows you to divide the system into two circuits: open, with a boiler and an expansion tank, and closed, including radiators and a closed membrane tank.
A heating boiler operating on various types of solid fuels differs in operation from gas and electric boilers. Here there are heating and cooling cycles associated with firewood loads, the danger of overheating of the coolant and low-temperature corrosion. Accordingly, the scheme for connecting a solid fuel boiler to the heating system of a building has its own characteristics. The purpose of this article is to show how to properly include the unit in the heating system, including in conjunction with other boiler plants.
The basic scheme of piping a solid fuel boiler
For a better understanding of the processes that occur during the operation of the heat generator, we will show its piping in the figure, and then we will analyze the purpose of each element. In the event that the heating unit is the only source of heat in the house, then it is recommended to use the following basic scheme to connect it:
Note. The basic scheme, where there is a small boiler circuit and a three-way valve, shown in the figure, is also mandatory for use when working with other types of heat generators.
So, the first on the path of movement of the coolant from the boiler plant is the safety group. It consists of three parts mounted on one manifold:
- pressure gauge - to control the pressure in the network;
- automatic air release valve;
- safety valve.
When operating a solid fuel boiler, there is always a risk of overheating of the coolant, especially in modes close to maximum power. This is due to some inertia of fuel combustion, because when the required water temperature is reached or the electricity is suddenly turned off, it will not be possible to immediately stop the process. Within a few minutes after the air supply is stopped, the coolant will still heat up, at which point there is a risk of vaporization. This leads to an increase in pressure in the network and the danger of destruction of the boiler or bursting of pipes.
To exclude emergency situations, the piping of a solid fuel boiler must necessarily include. It is adjusted to a certain critical pressure, whose value is indicated in the heat generator passport. As a rule, the value of this pressure in most systems is 3 bar, when it is reached, the valve opens, releasing steam and excess water.
Further, in accordance with the scheme, for the correct operation of the unit, it is necessary to organize a small coolant circulation circuit. Its task is to prevent cold water from entering the house heating system into the heat exchanger and the water jacket of the boiler. This is possible in 2 cases:
- when heating is started;
- when the pump stops due to a power outage, the water in the pipelines cools down, and then the power supply resumes.
Important! The power outage situation is particularly dangerous for cast iron heat exchangers. A sudden supply of cold water from the system by the pump can lead to cracking and loss of tightness.
If the furnace and heat exchanger are made of steel, then connecting the solid fuel boiler to the heating system through a three-way valve protects them from low-temperature corrosion. The phenomenon occurs if condensation forms on the inner walls of the combustion chamber due to temperature differences. Mixing with volatile fractions and ash, moisture forms a layer of scale on the steel walls, which is very difficult to remove. In this case, the metal is exposed to corrosion and the service life of the product as a whole is reduced.
The scheme works according to this principle: while the water in the boiler jacket and in the system is cold, the three-way valve allows it to circulate along the small circuit. After reaching a temperature of 60 ºС, the unit starts mixing the coolant from the network at the unit inlet, gradually increasing its consumption. Thus, all the water in the pipes warms up gradually and evenly.
Scheme with a heat accumulator
In a number of EU countries, rules have been introduced, according to which schemes for connecting solid fuel boilers to a heating system must necessarily include a heat accumulator. Without it, the operation of such heaters is simply prohibited. The reason is the high content of carbon monoxide (CO) in emissions during the restriction of oxygen supply to the furnace to reduce the intensity of combustion.
With normal access to air, harmless carbon dioxide (CO2) is formed, so the furnace must operate at full capacity, giving energy to the heat accumulator. Then the CO content will not exceed environmental standards. In the post-Soviet space, there are no such requirements yet, respectively, we continue to block the access of air in order to achieve slow decay of wood, for example, in.
Thermal accumulators are commercially available as a finished product, although many craftsmen make them themselves. By and large, this is a tank covered with a layer of thermal insulation. In the factory version, it can have a built-in DHW circuit and a heating element for heating water. This solution allows you to accumulate heat from a wood-burning boiler, and at times of its downtime, provide heating for the house for some time. The connection diagram of the boiler with a heat accumulator is shown in the figure:
Note. In the scheme, instead of a mixing unit consisting of several elements, a ready-made device is installed that performs the same functions - LADDOMAT 21.
Piping with an electric or gas boiler
Often, homeowners purchase a solid fuel boiler as their main source of heat, leaving an existing gas or electric unit in reserve. Usually it looks like this: while the owner of the house is awake, he devotes time to a wood-burning heat generator, but another type of heater is turned on at night. It is a sin not to connect these two boilers in such a way that the system works automatically, that is, when the firewood in the furnace dies out, an electric heater comes into play.
Of course, the scheme of parallel connection of a gas and solid fuel boiler through a buffer tank will work most efficiently. The latter will simultaneously perform 2 functions: to serve as a hydraulic separator and a heat accumulator.
While all heating systems operate from a heat generator on wood or coal, the gas boiler is in standby mode. But when the fuel in the chamber burns out, the temperature of the water in the buffer tank will decrease. This will automatically start the burner of the gas unit, since its circulation pump is constantly running. It will deliver the cooled water to the temperature sensor, which will start the main burner through the controller. When the furnace is ignited, the reverse process will follow, the gas burner will turn off due to the high temperature of the coolant.
It should be noted that the scheme for connecting a solid fuel boiler with an electric boiler through a buffer tank will be absolutely identical. But it has a significant drawback - the high cost. Such a device of the heating system is relevant for private houses of a large area, for small buildings there are simpler solutions:
Both boiler installations are connected in parallel, while check valves are installed at the outlet of each. Since the pump in the electric boiler is built-in, it works constantly and it is impossible to turn it off, it is necessary to choose the right pump for the solid fuel heat generator. The pressure of the latter must be higher so that when working together it has priority over the electric boiler.
This connection of the electric boiler to the solid fuel boiler will function automatically if two devices are installed:
- a thermostat that controls the operation of the biomass heat generator pump;
- room temperature sensor that controls the electric boiler.
During the burning of firewood, the room sensor will record the normal temperature in the house, so the electric heater will not turn on. But as soon as the fuel burns out, the air in the room will begin to cool, as well as the coolant in the pipes. The pump thermostat will turn it off when the water temperature drops, and the sensor will turn on the electric heat generator. For more information, please watch the video:
Conclusion
So, the scheme of the heating system with a solid fuel boiler should ensure its correct, and most importantly, safe operation. At the same time, it is necessary to provide for all individual installation conditions and tie the basic scheme in place, preferably with the recommendations of specialists.
The piping scheme for a solid fuel boiler is understood as the whole set of necessary devices and elements that together form a single heating system at home. It includes the boiler itself, heating devices (radiators, heated towel rails, underfloor heating), control and automation devices, shut-off and control valves, pipelines, etc. The choice of the optimal connection scheme and compliance with the basic rules when installing the boiler are the key to reliable and safe operation of the heating device during the entire period of its operation.
When installing any boiler CT piping scheme on your own, a number of mandatory requirements must be observed.
Mini-boiler room with a solid fuel floor boiler
Installation requirements:
- The operating temperature and pressure of the heat-carrying liquid at the outlet of the boiler must not exceed the values set for them, for which the use of special automatic protective devices and emergency connection schemes is provided.
- The difference between the temperatures of the coolant at the outlet and inlet of the boiler should not exceed more than 20 degrees. This is necessary to prevent the formation of condensed moisture inside its housing, which especially important for steel boilers.
- It is desirable to include automation devices in the boiler piping scheme, allowing you to adjust its power and maintain the optimum temperature of the coolant. You also need to turn on devices to increase its efficiency and versatility (hot water storage tanks, etc.).
It should be noted that compliance with these requirements is much more convenient to implement in forced circulation schemes, therefore they are most widely used among home boiler house owners.
In this article:
Basic strapping schemes
Depending on the number of boiler circuits, the type of heating system and the need to connect additional devices, the solid fuel boiler piping scheme can have many options.
Consider the most common ways to connect TT boilers.
To an open system with natural circulation
This scheme considered the easiest to implement, since it contains the minimum number of connected devices. Its main advantage lies in the complete independence from the availability of power in the house.
Disadvantage: it is impossible to control the temperature of the coolant at the outlet of the boiler and the ingress of oxygen into the coolant from an open expansion tank. This can cause accelerated corrosion of the inner surface of metal heating pipes and steel boilers.
Piping scheme for an open system with natural circulation
It requires special installation rules:
- the heating boiler must be located at least 0.5 m below the installation level of heating radiators (to create a stable natural circulation of the coolant);
- pipes must be sloped in the direction of circulation of the coolant and have a sufficiently large diameter to reduce their hydraulic resistance;
- an open-type expansion tank should be located at the highest point in the system;
- in the heating system, it is desirable to use the minimum number of valves and control devices that reduce the flow area of pipelines.
About the natural heating system.
To a closed system with natural circulation
In this scheme, a closed-type membrane tank is used, which is usually installed on the return line of the heating system. Its capacity must be at least 10% of the total volume of the coolant used in the heating system.
Piping the boiler to a closed system with natural circulation
With this boiler connection scheme, at the outlet of its supply pipe must be present an air vent and a safety valve for pressure relief, which is connected by a drain hose to the sewer.
These devices can be installed separately or included in the so-called TT safety group of the boiler, which is a separate device.
It includes:
- pressure gauge for visual control;
- pressure relief valve;
- air vent valve to bleed air from the system.
In some models of solid fuel boilers, these safety elements are already built into the boiler body.
To forced circulation system
Here for forced circulation of the heat-carrying liquid through the pipelines of the heating system. The pump is installed, as a rule, on the return line of the coolant supply between the boiler inlet pipe and the membrane tank.
The pump is controlled by a temperature sensor attached to the return line.
Connecting the boiler to a forced circulation system
The use of pumps for forced circulation significantly increases the efficiency of the system through the use of various temperature control equipment. However, it needs to be connected to a household power supply to operate, which increases power consumption and makes the system volatile from an uninterrupted power supply.
Collector connection method
The collector method of connecting a solid fuel boiler is used in forced circulation systems and provides for the inclusion of special devices in the piping circuit - collectors, also called combs.
They are sections of pipes of larger diameter with one inlet and several outlets, connected to the inlet and outlet of the boiler.
Piping of the TT boiler with a collector system
Circuit advantage:
- possibility of separate connection of each heating device. This allows you to supply them with a coolant of the same temperature and pressure, as well as more efficiently manage their work.
Flaw:
- high consumption of pipes and the complexity of their laying during installation of the system.
This is a special kind of piping using the so-called hydraulic arrow, which is a large diameter pipe installed vertically, connected to the inlet and outlet of the boiler.
Heating devices can be connected to the inlets and outlets of the hydraulic arrow at different heights.
This method of connecting heating devices allows you to select for each of them the optimal temperature of the coolant at the inlet and outlet.
To a system with an indirect DHW tank
The piping of a solid fuel boiler according to this scheme can be used in systems with any type of coolant circulation.
Connection to a system with a domestic hot water tank
The output supply line of the boiler is connected in parallel to the radiators and a heat exchanger (coil) built into a separate heat-insulated tank (boiler), in which water is heated for the DHW system. Thus, the functionality of the TT boiler is expanded, allowing it to additionally provide hot water at home during its operation.
At the inlet to the DHW heat exchanger, an automatic valve can be installed that shuts off the supply of coolant to it when the water is heated in the boiler as necessary.
To system with thermal storage
This connection scheme can be used in systems with any type of coolant circulation.
In the process of strapping, two circulation loops are formed:
- between the boiler and the heat accumulator (TA);
- between the TA and the main heating system.
Piping of a solid fuel boiler with a heat accumulator
During the operation of the boiler, the hot coolant enters the TA, which is a separate storage tank with a thermally insulated body. The heat exchanger gradually accumulates the heat generated by the boiler and, if necessary, transfers it to the heating system for heating devices.
After the boiler stops (fuel combustion ceases), the hot coolant stored in the HE continues to enter the system for some time, depending on the internal volume of the HE.
Such a connection scheme can significantly increase the efficiency of the boiler and reduce fuel consumption, and is also an effective means of protecting the boiler and all elements of the system from overheating.
Connection of emergency systems
The elements of emergency systems in the piping scheme are used for the following purposes:
- protection against increasing the maximum working pressure in the system;
- protection against exceeding the maximum allowable outlet temperature of the coolant, overheating of the boiler and elements of the heating system;
- preventing the formation of condensate in the boiler due to the large temperature difference of the coolant at the inlet and outlet of the device.
Safety valve
Protection of the boiler and system elements in case of excess of the working pressure of the heat-carrying liquid is provided by a safety valve installed on the supply line at the outlet of the boiler. Such a valve may be part of the boiler safety group, which is built into the boiler itself or connected separately.
How a safety valve works
A drain hose is connected to the pressure relief port of the valve. When the valve is actuated, the excess heat-carrying fluid from the system is drained through the hose into the sewer.
emergency heat exchanger
An emergency heat exchanger is needed to protect the boiler and system elements from overheating.
Overheating of equipment can occur in two cases:
- when the power generated by the boiler exceeds that required for heat consumers;
- when the circulation pump stops working due to its breakdown or power outage.
The heat exchanger consists of a cooling module and a thermal valve with an external thermal sensor set to a certain temperature. They can be installed inside the boiler itself or separately on the coolant supply line to the heating system.
How a heat exchanger works
When the permissible temperature is exceeded, the thermal valve is activated by a signal from a thermal sensor.
It supplies cold water from the water supply line to the cooling module, in which excess heat is removed from the coolant. From the cooling module, the water that has taken away the heat enters the sewer.
Additional circuit
The protection of the boiler against overheating in systems with forced circulation can also be ensured using an additional natural circulation circuit, to which a DHW storage tank is connected.
Boiler piping with an additional circuit
During normal operation of the system, the pressure created by the circulation pump in the main circuit closes the additional circuit with a check valve, preventing the heat-carrying liquid from circulating in it.
When the pump is turned off for any reason, the forced circulation of the coolant in the main circuit stops and natural circulation begins in the additional circuit. Due to this, the heat-carrying liquid in the system is cooled to the required temperature.
thermostatic mixer
Maintaining the minimum required temperature at the inlet to the boiler, in order to prevent the formation of condensate in it, is provided by a thermostatic mixer.
The device is installed on the return pipeline and connected to the supply line using a jumper (bypass).
Installing a thermostatic mixer
At a low temperature of the heat carrier in the return line, the thermal mixer opens and mixes hot liquid into it. After reaching the desired temperature, the thermal mixer closes and stops supplying hot coolant through the bypass to the return line.
This scheme can be used in systems with any type of circulation.
Can it be made from improvised means?
What is the advantage of double-circuit solid fuel heating boilers over similar devices with a single circuit. How can the power of the boiler be increased with the help of an additional circuit. available via link.
A good option is combined wood-gas heating boilers or two boilers, one of which runs on solid fuel and the other on gas.
Any of these two options makes it possible to receive heat in the case when there is no firewood left in the firebox, but there is still gas in the cylinder. It is better to combine two different boilers because the network will work constantly, even if one of the devices breaks. If the gas-firewood device breaks down, the system stops working and the room will be cold.
Difficulties of using two boilers in one system
The main difficulty lies in the fact that gas boilers for a private house must operate in a closed system, and the safest for solid fuel devices is an open one. in demand because the boiler can heat water to 110 ° C or more, raising the pressure above the permissible limits.
It can be lowered by reducing the intensity of combustion. But the effect will be visible when the coals are completely burned. Even with low combustion, they are very hot and continue to heat the water, raising the pressure.
In such a situation, you need to relieve pressure. Copes with this task expansion tank open type. When its volume is not enough, water is discharged into the sewer through a pipe installed between the tank and the sewer. Such a tank allows air to enter the coolant. This is bad for the internal elements of the gas boiler, pipes and. Problem Solutions:
- Combination of closed and open heating system by using a heat accumulator.
- Organization of a closed system for a wood or pellet boiler using a special security group. In this case, two units are connected in parallel and work both in pairs and separately.
Read also: sawdust boiler
Tying with a heat accumulator
The idea of using a heat accumulator lies in the following nuances:
- A gas boiler that receives gas from a cylinder and heating devices form one closed system. It includes a heat accumulator.
- Gas-fired boilers for wood, coal or pellets are also connected to a heat accumulator. But the water heated by them gives off heat to the heat accumulator, and then it is transferred to the coolant, which circulates through a closed system.
To make such a strapping with your own hands, you need to have:
- Open expansion tank.
- The hose that will be located between the tank and the sewer.
- Shut-off valves (13 pcs).
- Circulation pump (2 pcs).
- Three-way valve.
- Filter for water purification.
- Pipes made of steel or polypropylene.
The circuit can operate in four modes:
- From a wood-burning boiler with the transfer of degrees through a heat accumulator.
- From the same boiler bypassing the heat accumulator (the gas device will be turned off).
- From a gas boiler that can receive gas from a cylinder.
- from both boilers.
Organization of an open system with a heat accumulator
- Do-it-yourself installation of shut-off taps on two fittings of a wood-burning boiler.
- Expansion tank connection. It must be placed so that it is above all the strapping elements. The pressure under which a solid fuel boiler supplies water often exceeds the pressure under which the coolant is supplied from a gas boiler connected to a cylinder. To equalize these values, you need to correctly adjust the open expansion tank.
- Installation of taps on the branch pipes of the heat accumulator.
- Connection and boiler with two pipes.
- Connection of two tubes to pipes placed between the heat accumulator and the boiler. They are embedded near the taps, which are located near the battery fittings, or at a short distance from the shutoff valves. Shut-off valves are mounted on these tubes. Thanks to these pipes, it will be possible to use a solid fuel boiler bypassing the heat accumulator.
- Jumper notch. It connects the supply and return pipes located between the wood-burning boiler for the house and the heat accumulator. This jumper is attached to the supply line by welding or using fittings, and to the return line - using a three-way valve. A small circle is formed through which the coolant will circulate until it heats up to 60 ° C. After the water will move in a large circle through the heat accumulator.
- Filter and pump connection. Their mounted on the return line in the place between the three-way valve and the boiler heat exchanger pipe A. To do this, a U-shaped tube is connected in parallel to the line, in the middle of which there is a pump with a filter. There should be taps before and after these elements. This solution allows you to make, along which the coolant will move in the event of a power outage.
Read also: Solid fuel boilers for heating a private house
Closed system with thermal storage
It is not necessary to connect a device similar to an expansion tank because the gas boiler connected to the network or cylinder already incorporates a diaphragm expansion tank and also a safety valve.
To make this scheme correct, you need:
- Connect a tap and a pipe to the supply fitting of the gas device, which will be suitable for heating radiators.
- Place a circulation pump on this pipe in front of the heating devices.
- Connect your own heating devices.
- Take away from them a pipe that will fit the boiler. At its end, at a short distance from the gas unit, which is powered by a gas cylinder, you need to put a shut-off valve.
- Connect two pipes to the supply and return lines, which will fit to y. The first must be connected in front of the circulation pump, the second - immediately after the radiators. Shut-off valves are installed on both pipes. Two tubes are connected to these pipes, which were cut into the open system before entering and after leaving the heat accumulator.
Closed system with two boilers
This scheme provides parallel connection of two boilers. Particular attention is paid to the security group. Instead of an open expansion tank, a closed membrane one is installed in a special room.
The security group consists of:
- Air bleed valves.
- Safety valve for pressure reduction.
- pressure gauge.
The binding is done according to the following scheme:
- Cut-off valves are installed at the outlets of the heat exchangers of both boilers.
- On the supply line, which departs from, they install a security group with their own hands. The distance between it and the valve may be small.
- Connect the supply pipes of both boilers. At the same time, before connecting, a jumper is cut into the line that departs from the solid fuel boiler for the house (to organize a small circle). The tie-in point can be located at a distance of 1-2 m from the boiler. At a short distance from the jumper, a reverse petal valve is placed. If the wood-burning boiler stops working, the pressurized coolant created by the gas cylinder-operated unit will not be able to move along the supply line towards the solid fuel device.
- The supply line is connected to heating radiators located in different rooms and at different distances from each other.
- Install return line. It should be between the batteries and boilers. In one place it is divided into two pipes. One of them will be suitable for a gas boiler. On her a check valve is placed in front of the unit. The other pipe must be suitable for the solid fuel boiler. The aforementioned jumper is connected to it. A three-way valve is used for connection.
- Before branching the return line, it is worth putting a membrane tank and a circulation pump.
