Optimal heating schemes with a solid fuel boiler. How to wire a solid fuel boiler Connection diagram for a solid fuel boiler

The wiring diagram for a solid fuel boiler refers to the entire set of necessary devices and elements that together form a single heating system for the house. It includes the boiler itself, heating devices (radiators, heated towel rails, heated floors), control and automation devices, shut-off and control valves, pipelines, etc. Choosing the optimal connection diagram and following the basic rules when installing the boiler are the key to reliable and safe operation of the heating device throughout its entire service life.

At self-installation Any boiler TT piping scheme must comply with a number of mandatory requirements.

Mini boiler room with solid fuel floor boiler

Installation requirements:

The operating temperature and pressure of the heat-carrying fluid at the outlet of the boiler should not exceed the values established for them, for which the use of special automatic protective devices and emergency connection diagrams.
The temperature difference between the coolant at the boiler outlet and inlet should not exceed 20 degrees. This is necessary to prevent the formation of condensing moisture inside its housing, which especially important for steel boilers.
It is advisable to include automatic devices in the boiler piping scheme that allow you to regulate its power and maintain the optimal temperature of the coolant. You also need to include devices to increase its efficiency and versatility (storage tanks for hot water, etc.).

It should be noted that compliance with these requirements is much more convenient to implement in forced circulation circuits, which is why they are most widespread among owners of home boiler rooms.

In this article:

Basic strapping patterns

Depending on the number of boiler circuits, the type of heating system and the need to connect additional devices, the piping circuit of a solid fuel boiler can have many options.

Let's look at the most common methods of connecting TT boilers.

To an open type system with natural circulation

This scheme considered the easiest to implement, since it contains minimum quantity connected devices. Its main advantage is its complete independence from the availability of power in the house.

Disadvantage: it is impossible to regulate the temperature of the coolant at the outlet of the boiler and the entry of oxygen into the coolant from the open expansion tank. This may cause accelerated corrosion inner surface metal pipes heating and steel boilers.

Piping diagram 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 stable natural coolant circulation);
the pipes must be located at a slope in the direction of coolant circulation and have a sufficiently large diameter to reduce their hydraulic resistance;
the open type expansion tank should be located at the highest point of the system;
in the heating system it is advisable to use a minimum amount shut-off valves and control devices that reduce the flow area of pipelines.

About the natural heating system.

Towards a closed system with natural circulation

This scheme uses a closed-type membrane tank, which is usually installed on the return line of the heating system. Its capacity must be at least 10% of the total volume of coolant used in the heating system.

Piping the boiler to a closed system with natural circulation

With this scheme for connecting the boiler at the outlet of its supply pipe must be present an air vent and a pressure relief valve, which is connected by a drain hose to the sewer.

These devices can be installed separately or included in the so-called TT boiler safety group, which is a separate device.

It includes:

pressure gauge for visual control;
safety valve for pressure relief;
air bleed 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 a forced circulation system

Here for forced circulation of heat-carrying fluid through the pipelines of the heating system. The pump is usually installed on the return coolant supply line between the boiler inlet pipe and the membrane tank.

The operation of the pump is controlled by a temperature sensor mounted on 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, for its operation it is necessary to connect to a household power supply, which increases energy consumption and makes the system energy dependent on an uninterrupted power supply.

Collector connection method

The collector method of connecting a solid fuel boiler is used in forced circulation systems and involves the inclusion of special devices in the piping circuit - collectors, also called combs.

They are sections of larger diameter pipes with one inlet and several outlets, connected to the inlet and outlet of the boiler.

Piping the boiler heat exchanger with the manifold system

Advantage of the scheme:

possibility of separate connection of each heating device. This allows you to supply them with coolant of the same temperature and pressure, as well as more efficiently control their operation.

Flaw:

high consumption of pipes and the complexity of their installation during installation of the system.

This is a special type of piping using the so-called hydraulic arrow, which is a pipe installed vertically large diameter, connected to the input and output of the boiler.

Heating devices can be connected to the inputs and outputs of the hydraulic arrow at different heights.

This method of connecting heating devices allows you to select the optimal coolant temperature at the inlet and outlet for each of them.

To a system with an indirect hot water boiler

Piping 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 DHW boiler

The output supply line of the boiler is connected in parallel to heating radiators and a heat exchanger (coil), built into a separate thermally insulated container (boiler), in which water is heated for the DHW system. This expands the functionality of the TT boiler, allowing it to additionally provide hot water to the home during its operation.

An automatic valve can be installed at the entrance to the DHW heat exchanger, shutting off the supply of coolant to it when the water in the boiler is heated as necessary.

To a system with a heat accumulator

This connection diagram can be used in systems with any type of coolant circulation.

During the tying process, two circulation circuits are formed:

between the boiler and the heat accumulator (TA);
between the heating unit and the main heating system.

Connecting a solid fuel boiler with a heat accumulator

During 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 stops), the hot coolant stored in the heat exchanger continues to flow into the system for some time, depending on the internal volume of the heat exchanger.

This connection scheme allows you to significantly increase the efficiency of the boiler and reduce fuel consumption, and is also effective means protecting the boiler and all system elements from overheating.

Connecting emergency systems

Elements of emergency systems in the wiring diagram are used for the following purposes:

protection against increasing the maximum operating pressure in the system;
protection against exceeding the maximum permissible output temperature of the coolant, overheating of the boiler and heating system elements;
preventing the formation of condensation in the boiler due to a large temperature difference of the coolant at the inlet and outlet of the device.

Safety valve

Protection of the boiler and system elements when the operating pressure of the heat-carrying liquid is exceeded is provided by a safety valve installed on the supply line at the outlet of the boiler. Such a valve can be part of a boiler safety group, which is built into the boiler itself or connected separately.

How does a safety valve work?

A drain hose is connected to the pressure relief port of the valve. When the valve is activated, excess heat-carrying liquid from the system is drained into the sewer through a hose.

Emergency heat exchanger

An emergency heat exchanger is needed to protect the boiler and system elements from overheating.

Equipment overheating 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 a remote 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 does a heat exchanger work?

When the permissible temperature is exceeded, the thermal valve is activated by a signal from the 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 removed the heat goes into the sewer system.

Additional circuit

Protection of the boiler from overheating in systems with forced circulation can also be ensured using an additional circuit with natural circulation, to which a storage tank for hot water 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 using a check valve, preventing the heat-carrying fluid 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 boiler inlet to prevent the formation of condensation in it is ensured by a thermostatic mixer.

The device is installed on the return pipeline and connected to the supply line using a jumper (bypass).

Installation of a thermostatic mixer

When the temperature of the coolant in the return line is low, the thermal mixer opens and mixes hot liquid into it. After reaching the desired temperature, the thermomixer closes and stops supplying hot coolant through the bypass to the return.

This scheme can be used in systems with any type of circulation.

Can it be made from improvised materials?

What is the advantage of double-circuit solid fuel heating boilers over similar devices with a single circuit. How can you use an additional circuit to increase the power of the boiler? available via the link.

When installing a heat generator heat generator in a boiler room, the piping of a solid fuel boiler most closely resembles the same circuit for a diesel unit. Why? Because, as you know, there are no wall-mounted TT boilers, just like diesel ones. All other heat generators - gas, electric, etc., are wall-mounted.

Accordingly, in many cases, heating piping can be implemented in the same way as for other floor-standing boilers. At the same time, the connection diagram for a solid fuel heating boiler still differs in a couple of points. About them - below.

Main options for connecting a TT boiler

So, let's see. Before connecting a solid fuel heating boiler, you need to prepare the boiler room to “receive” it. Misha Vokhmyanin will write about what kind of room this should be, he has material for this, he recently wrote an article for a construction magazine, collected all the parameters.

I will only say that the installation diagram of a solid fuel boiler implies a reinforced base for some models. This is not a separate foundation like for a brick heating stove; after all, not a single household TT boiler weighs 5-7 tons.

But a heat generator weighing 300-450 kilograms can no longer be simply placed on the floor wooden joists in any room of a residential building. And that’s exactly how much a good one weighs in its entirety – both the firebox and the fire-tube heat exchanger.

Moreover, large mines with a large volumetric firebox, for example, also weigh a lot, even steel ones.

So, regarding our question, let's look at connecting a solid fuel boiler using several options. The connection diagram for a solid fuel heating boiler to CO can be implemented in the following forms:

TT boiler in an open heating system with EC and radiators.
TT boiler in a closed heating system with a PC with radiators.
TT boiler with heat accumulator in a closed system with a PC with radiators.
TT boiler with heat accumulator in a closed system with a PC with heated floors.
Combined diagram for connecting a solid fuel boiler in a heating system with radiators and heated floors.

Let's immediately make a reservation that any low-temperature heating systems, which include a system with a TP, will require additional devices that will be responsible for the safety of the system and for its trouble-free operation.

The piping of a solid fuel boiler will have to include the following additional elements:

Thermal accumulator or buffer tank - they have different volumes.
Three-way valve for a solid fuel boiler - allows for the addition of cold water.
Mandatory thermostat in the control system of a solid fuel boiler.

If we talk about a simple heating system with radiators, then you can connect it directly, through the security group. However, in order to prevent the system from boiling and to mitigate surges during thermal expansion of the system when the boiler reaches full power, the piping circuit of the solid fuel boiler includes a buffer tank.

The buffer tank is not a heat accumulator. Although the heat accumulator can be used as a buffer tank. The buffer tank, also called a capacitive hydraulic separator, has a minimum volume selected on the basis that for every 1000 watts of boiler thermal power there are 10 liters of tank.

That is, on a 20 kW boiler you need to install a container with a volume of 200 liters. It will not work to use a buffer tank as a heat accumulator. The minimum volume of an effective heat accumulator for a small house starts from 800-1000 liters.

TT boiler piping diagram

Proper piping of a solid fuel boiler with your own hands can only be done if the rules for such work are fully observed. I already wrote about it - it has its own characteristics.

Let's start with the return, that is, with the entrance of cold water into the heat generator. On the return it is placed circulation pump, in the case of using closed CO with forced circulation. The pump is placed precisely on the return line; it pumps water into the boiler. If the central heating unit is installed on the supply from the boiler, then it will not last long there.

Why? Because the coolant output from the boiler heat exchanger is high temperature.

If diesel or gas boilers give at the output from 40 to 65 degrees, set by the boiler automation, then at the output of the boiler TT - from 60 to 90 degrees in normal mode.

The cold water supply pipe is connected to the boiler inlet pipe. It is usually located at the bottom of the boiler.

The hot water supply pipe from the boiler is connected to the boiler outlet. Typically this pipe is located at the top of the boiler. This arrangement allows the use of .

The hot water outlet pipe from the boiler has a normal temperature of 60 to 90 degrees Celsius. In abnormal mode, the pipe can have a superheated steam temperature of 105-110 degrees Celsius on the inner surface, and up to 200-350 degrees Celsius on the outer part near the boiler pipe - from the superheated boiler itself.

Therefore, it must be made of metal, preferably copper. Although steel pipe will also cope with its responsibilities properly.

The basic rule that is established by the piping diagram of a solid fuel boiler is that there should be no shut-off valves between the heating system and the expansion tank.

What is included in the boiler safety group

The safety group of a solid fuel boiler includes three elements:

A pressure gauge showing the pressure in the system at the boiler outlet.
Emergency pressure relief valve, set to the upper value of the permissible pressure in the CO.
Automatic air vent.

For ease of use, the safety group pressure gauge has an additional manually installed arrow, which shows the limit of permissible coolant pressure in the heating system.

The emergency pressure relief valve is configured to release the coolant when the set pressure limit is exceeded. Typically, the operating pressure in the heating system is 1.5-2 atm, the relief valve is set to 3 atm.

The air vent removes air when the heating system is filled with coolant. When the operating level is reached, the air vent valve closes.

The safety group of a solid fuel boiler should be installed at the outlet of the boiler heater, at the hot water supply to the heating system. Only such a scheme for piping a solid fuel boiler using a safety group is correct.

It happened to me that it was installed on the return line of the heating system. In this case, the boiler may explode, the pipes of the heating system will melt, and the safety group will still not work.

Adding cold water to the heating system with a TT boiler

To mix cold water into the heating system, a three-way valve is used for a solid fuel boiler. This device allows you to maintain the set temperature in the following systems:

Heating system with heat accumulator.
Low temperature heating system with heated floors.

A three-way valve for a solid fuel boiler mixes cold water from the return into the hot water supply from the boiler, thereby regulating the overall supply temperature. If the supply temperature to the heated floors is set at 45 degrees Celsius, and at the outlet from the boiler, for example, 70 degrees Celsius, the three-way valve will interfere hot water from the supply and cooled water from the return to the desired value.

To effectively use a three-way valve for a solid fuel boiler, you need to install it after the heat accumulator. In this case, the water will be heated in the heat accumulator, and the three-way valve will interfere with the hot water from the heat accumulator. cold water from the return line.

Solid fuel boiler wiring diagram:

Boiler installation diagram and procedure

Please note that installation is a very important matter, and any mistake will result in at least incorrect functioning of the system. But if you are not afraid to take risks, let’s turn to our step-by-step instructions.

How to install a solid fuel boiler - step by step diagram

Step 1: Select a location

Such equipment should be placed in a separate room. Basements or basements are most often used as a boiler room. ground floors. Hot coals from the firebox can fall onto the floor, so the base under the boiler must be perfectly level and non-flammable. A concrete slab is perfect. Be sure to ensure that the body is in a strictly vertical position. Its distortions are unacceptable.

You also need to maintain the following distances. There should be more than half a meter between the back surface of the heating unit and the wall. And from the front side of the boiler to other objects and surfaces, a distance of at least 125 cm is maintained. The ceiling height cannot be less than 250 cm, and the volume of the room in which it is located heating equipment, must be more than 15 cubic meters. Treat the floor and walls of the boiler room with special fire-fighting agents and take care of a good exhaust system.

Step 2: Preparing components

The circuit consists of a radiator, a pipe, a circulation pump, an expansion tank and the heating unit itself. The kit also includes a heat accumulator, air and safety valves, a pressure gauge and a thermostat. Be sure to check the serviceability of all elements when purchasing and give preference only to reliable manufacturers.

Step 3: Hardware Installation

We display the unit in the boiler room, adhering to all the above requirements. Pay special attention to the position of the body; it should be positioned strictly horizontally. Therefore, check the prepared area again with a level to see if it is level enough. Then we connect all electric heaters, if any are included in the package. In principle, there is nothing complicated about this, since there is a special place in the boiler itself where the heating element will be located, and next to this element there is a thermostat.

Step 4: Install Piping and Electronics

Connection diagrams for solid fuel boilers assume the presence of pipes. It is best to connect them through shut-off valves. The joints are additionally sealed with flax fibers or special plumbing tape. If we are talking about volatile units, then they, accordingly, should be connected to the network. Don't forget about grounding. Next, we install all the devices responsible for the safe operation of the equipment. This is a thermostat, valves, pressure gauge, draft sensor.

Step 5: Installation of the chimney

There is no need to post today chimney made of brick, you can assemble it from special plastic elements. At the same time The diameter of the components is selected depending on the power of the equipment. Therefore, be sure to follow the recommendations given in the operating instructions for the selected boiler. Moreover, this stage is especially important, because the key to high-quality operation of a thermal unit is good traction.

Step 6: Filling the Outline

First, we fill the heating circuit with water so that the pressure is slightly higher than the working pressure, and carefully inspect the entire system, especially the joints. This way you will identify all leaks, if any. Then we carefully check whether the internal elements of the firebox are positioned correctly. These include the ignition valve, grates, fireclay stones and plugs.

Step 7: Connection

If the entire circuit is in order, no leaks are detected, then you need to relieve the pressure to operating pressure, adjust the position of the dampers and begin directly operating the heating device. To do this, add and light the fuel, and after 10 minutes close the damper. As soon as the temperature reaches 80 degrees, set the thermostat to the desired level. All that remains is to add firewood in time and enjoy the comfortable microclimate.

The efficiency of the solid fuel boiler depends on how correctly the piping is done. further work and service life. In operation, wood and coal heat generators differ from units using other types of fuel, and therefore require a special approach.

It is proposed to consider in detail how, after installing the heating wiring, to connect a solid fuel boiler, including with your own hands. A description of various schemes for connecting a TT boiler to a heating system can be found in this material.

What is the difference between solid fuel boilers

In addition to burning various types of solid fuel, heat generators have a number of differences from other heat sources. These features should be taken for granted and always taken into account when connecting a solid fuel boiler to a water heating system. What are they:

High inertia. At the moment, there are no ways to quickly extinguish a fire solid fuel in the combustion chamber.
Formation of condensation in the firebox during heating. The peculiarity is manifested due to the flow of coolant with a low temperature (below 50 ° C) into the boiler tank.

Note. The phenomenon of inertia is absent only in one type of solid fuel units - pellet boilers. They have a burner into which wood pellets are fed in doses; after the supply is stopped, the flame goes out almost immediately.

Diagram of a direct combustion TT boiler with forced air injection

Inertia creates the danger of overheating the water jacket of the heater, as a result of which the coolant in it boils. Steam is generated, which creates high pressure, rupturing the body of the unit and part of the supply pipeline. As a result, there is a lot of water in the furnace room, a lot of steam and a solid fuel boiler unsuitable for further use.

A similar situation can arise when the heat generator piping is done incorrectly. After all, in fact, the normal operating mode of wood-burning boilers is maximum; it is at this time that the unit reaches its rated efficiency. When the thermostat reacts to the coolant reaching a temperature of 85 °C and closes the air damper, combustion and smoldering in the firebox still continues. The water temperature rises another 2-4 °C, or even more, before its growth stops.

In order to avoid excess pressure and a subsequent accident, an important element is always involved in the piping of a solid fuel boiler - a safety group, which will be discussed in more detail below.

Another unpleasant feature of the unit operating on wood is the appearance of condensation on the inner walls of the firebox due to the passage of not yet heated coolant through the water jacket. This condensation is not at all God's dew, since it is an aggressive liquid that quickly corrodes the steel walls of the combustion chamber. Then, having mixed with the ash, the condensate turns into a sticky substance that is not so easy to tear off from the surface. The problem is solved by installing a mixing unit in the piping circuit of a solid fuel boiler.

This coating serves as a heat insulator and reduces the efficiency of a solid fuel boiler.

It is too early to breathe a sigh of relief for owners of heat generators with cast iron heat exchangers that are not afraid of corrosion. Another misfortune may await them - the possibility of destruction of cast iron from temperature shock. Imagine that in a private house the power was turned off for 20-30 minutes and the circulation pump driving water through the solid fuel boiler stopped. During this time, the water in the radiators has time to cool down, and in the heat exchanger it has time to heat up (due to the same inertia).

Electricity appears, the pump turns on and directs the cooled coolant from closed system heating. Due to a sharp temperature change, the heat exchanger experiences a temperature shock, the cast iron section cracks, and water runs onto the floor. It is very difficult to repair; it is not always possible to replace a section. So even in this situation, the mixing unit will prevent an accident, which will be discussed below.

Emergency situations and their consequences are described not with the aim of scaring users of solid fuel boilers or encouraging them to purchase unnecessary elements of piping schemes. The description is based on practical experience, which must always be taken into account. If the heating unit is connected correctly, the likelihood of such consequences is extremely low, almost the same as with heat generators using other types of fuel.

How to connect a solid fuel boiler

The canonical connection diagram for a solid fuel boiler contains two main elements that allow it to function reliably in the heating system of a private home. This is a safety group and a mixing unit based on a temperature sensor, shown in the figure:

The always open output of the mixing valve (the left pipe in the diagram) must be directed to the pump and heat generator, otherwise there will be no circulation in the small boiler circuit

Note. Not shown here expansion tank- it must be connected to the return line of the heating system in front of the pump (in the direction of water flow).

The presented diagram shows how to connect the unit correctly and is used with any solid fuel boilers, including pellet ones. You can find various general heating schemes - with a heat accumulator, an indirect heating boiler or a hydraulic arrow, in which this unit is not shown, but it must be there. The method of protecting against moisture loss in the firebox is discussed in detail in the video:

The task of the safety group, installed directly at the outlet of the supply pipe of a solid fuel boiler, is to automatically relieve pressure in the network when it rises above a set value (usually 3 Bar). This is done, and in addition to it, the element is also equipped with a pressure gauge. The first releases the air appearing in the coolant, the second serves to control the pressure.

Attention! The installation of any shut-off valves is not allowed on the section of the pipeline between the safety group and the boiler. If you installed a ball valve to cut off and repair group parts, remove the handle from the stem.

How the scheme works

The mixing unit, which protects the heat generator from condensation and temperature changes, operates according to the following algorithm, starting from kindling:

The firewood is just starting to burn, the pump is on, the valve on the side of the heating system is closed. The coolant circulates in a small circle through the bypass.
When the temperature in the return pipeline rises to 50-55 °C, where the attached remote-type sensor is located, the thermal head, at its command, begins to press the three-way valve stem.
The valve slowly opens and cold water gradually enters the boiler, mixing with hot water from the bypass.
As all the radiators warm up, the overall temperature increases and then the valve closes the bypass completely, passing all the coolant through the heat exchanger of the unit.

An important nuance. Paired with a 3-way valve, a special head with a sensor and capillary is installed, designed to regulate the water temperature in a certain range (for example, 40...70 or 50...80 degrees). A regular radiator thermal head will not work.

This piping scheme is the simplest and most reliable; you can easily install it yourself and thus ensure the safe operation of the solid fuel boiler. There are a couple of recommendations regarding this, especially when piping a wood-burning heater in a private house with polypropylene or other polymer pipes:

Make the section of the pipe from the boiler to metal, and then lay plastic.
Thick-walled polypropylene conducts heat poorly, which is why the surface-mounted sensor will openly lie, and the three-way valve will lag. For correct operation of the unit, the area between the pump and the heat generator, where the copper flask is located, must also be metal.

Connecting with copper pipes will not protect polypropylene from destruction in the event of overheating of the TT boiler. But it will allow the temperature sensor to work correctly and safety valve on the security group

Another point is the installation location of the circulation pump. It is best for him to stand where he is shown in the diagram - on the return line in front of the wood-burning boiler. In general, you can install the pump on the supply side, but remember what was said above: in an emergency, steam may appear in the supply pipe.

The pump is unable to pump gases, so when the chamber is filled with steam, the impeller will stop and the coolant circulation will stop. This will speed up a possible explosion of the boiler, because it will not be cooled by water flowing from the return.

Way to reduce the cost of strapping

The condensate protection circuit can be reduced in cost by installing a three-way mixing valve of a simplified design that does not require connecting an overhead temperature sensor and thermal head. It already has a thermostatic element installed, set to a fixed mixture temperature of 55 or 60 °C, as shown in the figure:

Special 3-way valve for solid fuel heating units HERZ-Teplomix

Note. Similar valves that maintain a fixed temperature of mixed water at the outlet and are intended for installation in the primary circuit of a solid fuel boiler are produced by many famous brands— Herz Armaturen, Danfoss, Regulus and others.

Installing such an element definitely allows you to save on piping the TT boiler. But in this case, the possibility of changing the temperature of the coolant using a thermal head is lost, and its deviation at the output can reach 1-2 °C. In most cases, these shortcomings are insignificant.

Trim option with buffer tank

The presence of a buffer tank is extremely desirable for the operation of a boiler using solid fuels and here’s why. In order for the unit to function efficiently and produce heat with the efficiency declared in the passport (from 75 to 85% for different types), it must operate at maximum mode. When the air damper is closed to slow down combustion, there is a lack of oxygen in the firebox and the efficiency of wood burning decreases. At the same time, emissions of carbon monoxide (CO) into the atmosphere increase.

For reference. It is because of emissions that in most European countries it is prohibited to operate solid fuel boilers without a buffer tank.

On the other hand, at maximum combustion, the temperature of the coolant in modern heat generators reaches 85 ° C, and one load of firewood lasts only 4 hours. This does not suit many owners of private houses. The solution to the problem is to install a buffer tank and connect it to the TT boiler piping so that it serves as a storage tank. Schematically it looks like this:

By measuring the temperatures T1 and T2, you can configure the layer-by-layer loading of the container with a balancing valve

When the firebox is burning with all its might, the buffer tank accumulates heat (for technical language– loads), and after extinguishing it sends it to the heating system. To control the temperature of the coolant supplied to the radiators, a three-way mixing valve and a second pump are also installed on the other side of the storage tank. Now it is not at all necessary to run to the boiler every 4 hours, because after the firebox goes out, the heating of the house will be provided for some time by the buffer tank. How long depends on its volume and heating temperature.

Reference. Based on practical experience, the capacity of a heat accumulator can be determined as follows: private house with an area of 200 m² you will need a tank with a volume of at least 1 m³.

There are a couple of important nuances. In order for the piping circuit to work safely, you need a solid fuel boiler whose power is sufficient for simultaneous heating and loading of the buffer tank. This means that power will be required 2 times higher than the calculated one. Another point is to select the pump performance so that the flow rate in the boiler circuit is slightly higher than the amount of water flowing in the heating circuit.

An interesting option for connecting a TT boiler with a homemade buffer tank (aka an indirect heating boiler) without a pump is demonstrated in our video:

Joint connection of two boilers

To increase the heating comfort of a private home, many owners install two or more heat sources that run on different energy sources. At the moment, the most relevant combinations of boilers are:

natural gas and wood;
solid fuel and electricity.

Accordingly, the gas and solid fuel boiler must be connected in such a way that the second automatically replaces the first after burning the next portion of firewood. The same requirements are put forward for connecting an electric boiler to a wood boiler. This is quite simple to do when a buffer tank is involved in the piping scheme, since it simultaneously plays the role of a hydraulic arrow, as shown in the figure.

The boiler supply lines are connected to the upper pipes of the heat accumulator, the return pipes to the lower ones

Advice. You will find information on calculating the volume of the buffer tank.

As you can see, thanks to the presence of an intermediate storage tank, 2 different boilers can serve several distribution heating circuits at once - radiators and heated floors, and in addition load an indirect heating boiler. But not everyone installs a heat accumulator with a TT boiler, since this is not a cheap pleasure. For this case there is simple circuit, and you can install it yourself:

The circuit takes into account the peculiarity of the electric boiler - the built-in circulation pump always works

Note. The scheme is valid for both electric and gas heat generators operating together with solid fuel.

Here the main source of heat is a wood heater. After a stack of firewood burns out, the air temperature in the house begins to drop, which is registered by the room thermostat sensor and immediately turns on heating by the electric boiler. Without a new load of firewood, the temperature in the supply pipe decreases and the overhead mechanical thermostat turns off the pump of the solid fuel unit. If you ignite it after some time, everything will happen in the reverse order. This video is described in detail about this joint connection method:

Tying using the method of primary and secondary rings

There is another way to combine a solid fuel boiler with an electric one to supply a large number of consumers. This is a method of primary and secondary circulation rings, which provides for hydraulic separation of flows, but without the use of a hydraulic needle. Also, for reliable operation of the system, a minimum of electronics is required, and a controller is not needed at all, despite the apparent complexity of the circuit:

The trick is that all consumers and boilers are connected to one primary circulation ring by both the supply and return pipelines. Due to the small distance between connections (up to 300 mm), the pressure drop is minimal compared to the pressure of the main circuit pump. Due to this, the movement of water in the primary ring does not depend on the operation of the secondary ring pumps. Only the temperature of the coolant changes.

Theoretically, any number of heat sources and secondary rings can be included in the main circuit. The main thing is to choose the right pipe diameters and the performance of the pumping units. The actual performance of the main ring pump must exceed the flow rate in the most “gluttonous” secondary circuit.

To achieve this, it is necessary to perform a hydraulic calculation and only then will it be possible to select the right pumps, so an ordinary homeowner cannot do without the help of specialists. In addition, it is necessary to link the operation of solid fuel and electric boilers by installing shut-off thermostats, as described in the following video:

Conclusion

As you can see, piping a solid fuel boiler correctly is not so easy. The issue must be approached responsibly and before carrying out installation and connection work, additionally consult with a specialist whose qualifications are beyond doubt. For example, with someone who gives explanations in the presented videos.

Optimal heating schemes with a solid fuel boiler. How to wire a solid fuel boiler. Connection diagram for a solid fuel boiler.