A feature of solid fuel boilers is the need to load firewood to maintain heat in heating appliances, this requires constant attention from the residents. The solution to the problem in such a situation can be called connecting a heat accumulator, installing an additional boiler in the heating system, or using two boilers at the same time: solid fuel and gas.

In this case, heat is supplied to the batteries if the firewood in the firebox has already run out, but there is gas in the cylinder. As an alternative, you can install a wood-gas unit, which does not require special costs and efforts for installation work. But practical application has shown that connecting two boilers to one system is much more efficient and profitable. When connecting a gas and solid fuel boiler at the same time, the system is in constant operation even if one of the devices fails. The breakdown of the boiler, which runs on gas and wood, leads to a shutdown of the entire system and it becomes cold in the rooms.

What is the difficulty of connecting two boilers

The main difficulty in using two boilers in one heating system is the need to equip different types of piping. Two gas boilers in one house can only be installed with a closed heating system. That is, connecting a gas boiler to the heating system will not cause problems. And for solid fuel units, an open system is needed. The fact is that the second version of the boiler is capable of heating water to a very high temperature, which leads to an increase in pressure in the system. Even with weak combustion of coals, the coolant continues to heat up.

In such a situation, pressure relief in the heating network is required, for which an open-type expansion tank is cut into the circuit. If the volume of this element of the system is insufficient, a separate pipe can be brought into the sewer to drain excess coolant. However, the installation of such a tank can cause air to enter the coolant, which can damage the internal elements of the gas boiler, pipes and heating devices.

To avoid all these difficulties of connecting two boilers to one heating system at the same time, you can use two options:

• Use a heat accumulator - a device that allows you to combine a closed and open heating system.
• Organize a closed heating circuit for a solid fuel and pellet boiler using a special security group. In this case, the units can work autonomously and in parallel.

Arrangement of a heating system with a heat accumulator

The use of such an element in a scheme with two boilers in one heating system has several features, depending on the installed units:

• The heat accumulator, gas boiler and heating devices form a single closed system.
• Solid fuel boilers, working on wood, pellets or coal, heat water, thermal energy is transferred to a heat accumulator. It, in turn, heats the coolant circulating in a closed heating circuit.

To independently create a heating scheme with two boilers, you must purchase the following:

• Boiler.
• Heat accumulator.
• Expansion tank of the appropriate volume.
• Hose for additional removal of the coolant.
• Shut-off valves in the amount of 13 pieces.
• Pump for forced circulation of the coolant in the amount of 2 pieces.
• Three-way valve.
• Water filter.
• Steel or polypropylene pipes.

Such a scheme is characterized by operation in several modes:

• Transfer of thermal energy from a solid fuel boiler by means of a heat accumulator.
• Heating water with a solid fuel boiler without using this device.
• Receiving heat from a gas boiler connected to a gas cylinder.
• Connecting two boilers at the same time.

Assembly of an open type system with a heat accumulator

The organization of this type of heating system is carried out according to the following scheme:

• Shut-off valves are installed on two fittings of a solid fuel boiler.
• Connect the expansion tank. At the same time, its location should be at the highest level relative to other elements of the heating circuit.
• Taps are also installed on the pipes of the heat accumulator.
• Connect the boiler and the heat accumulator through two pipes.
• Two tubes are cut into the circuit between the heat accumulator and the boiler, stepping back a short distance from the taps. Shut-off valves are also installed on these tubes. Additional tubes will allow heating the coolant from a solid fuel boiler without using a heat accumulator.

• Next, a jumper is cut in to connect the supply and return pipes in the gap between the heat accumulator and the boiler. Welding or fittings can be used to fasten the jumper to the supply; the jumper is fixed on the return pipe by means of a three-way valve. In the formed small circle, the coolant circulates until its temperature reaches 60 degrees. With stronger heating, the water begins to move in a large circle, capturing the heat accumulator.
• Connect a water filter and a circulation pump. Both devices must be installed on the return pipe of the heating circuit, the gap between the boiler and the three-way valve is considered the best place. Here they have a tap with a pump and a filter. It should be remembered that cranes are necessarily mounted before and after these elements. The advantage of a U-shaped outlet is the ability to install a bypass, it will carry out the movement of the coolant in the absence of electricity. Naturally, a gas boiler room in a private house should have enough space to accommodate all the necessary equipment.

Closed system with heat accumulator

A closed heating system does not require the installation of an expansion tank, so the installation process is greatly simplified. Most often, gas boilers are equipped with an expansion tank and a safety valve.

For the correct assembly of such a heating circuit, it is necessary to follow certain instructions:

• A tap and a pipe going to the heating appliances are connected to the supply fitting of the gas boiler.
• A pump for forced circulation of the coolant is installed on this pipe. It should be placed in front of the radiators.
• Each radiator is connected in series.
• A pipe leading to the heating boiler is diverted from them. At the end of the pipe at a short distance from the unit, powered by a gas cylinder, a shut-off valve is installed.
• Pipes leading to the heat accumulator are connected to the supply and return pipes. One of the tubes is connected in front of the pump, the second tube is connected behind the heating devices. Each tube is equipped with a tap, and tubes should also be connected here, which were previously embedded in front of and after the heat accumulator.

Installation of a closed system with two boilers - gas and solid fuel

When arranging such a heating system, a solid fuel and gas boiler in one circuit are connected in parallel with the mandatory installation of a security group. The open expansion tank is replaced by a closed membrane tank, which is located in a special room.

The security group contains the following elements:

• Valve to remove accumulated air.
• Safety valve, with which you can reduce the pressure in the system.
• Pressure gauge.

The question of how to connect two boilers, gas and solid, is solved in the following order:

• On the pipes coming from the heat exchangers of the gas and solid fuel boilers in the same system, shut-off valves are installed.
• A safety group is located on the supply pipe coming from the solid fuel unit. However, it can be placed near the valve.
• The supply pipes of both boilers are connected. Previously, a jumper cuts into the line coming from the solid fuel boiler, along which the movement of the coolant in a small circle will be organized. The distance from the boiler to the tie-in point can be up to 2 meters. A reed valve is installed next to the jumper. When the wood-fired boiler is turned off, such a scheme does not allow the coolant to enter the boiler, despite the strong pressure that the gas boiler creates.
• The supply line is connected to heating devices that are located in different rooms and at different distances from each other.
• Between boilers and heaters, a return line is installed. In a certain place, it is divided into two pipes: one is directed to a gas boiler, the other to a solid fuel unit. A spring valve is installed in front of the device powered by a gas cylinder. A jumper and a three-way valve are connected to another pipe.
• A membrane expansion tank and a pump for forced circulation of the coolant are mounted on the site before the separation of the return line.

The scheme for connecting two boilers to one system may well be used when installing a universal combined heating boiler.

The creation of a heating circuit in which two boilers in a heating system work either alone or together is associated with the desire to provide redundancy or reduce heating costs. The joint operation of boilers in an integrated system has a number of connection features that should be considered.

Possible options - two boilers in one heating system:

• gas and electricity;
• solid fuel and electricity;
• solid fuel and gas.

Combining a gas boiler with an electric boiler in one circuit, as a result of which a heating system with two boilers is created, can be implemented quite simply. Both serial and parallel connection is possible. In this case, a parallel connection is preferable, because. you can leave one boiler running and the other completely shut down, switched off or replaced. Such a system can be completely closed, and ethylene glycol can be used as a coolant for heating systems or.

Joint operation of a gas and solid fuel boiler

This is the most difficult option for technical implementation. In a solid fuel boiler, it is extremely difficult to control the heating of the coolant. Typically, such boilers operate in open systems, and the excess pressure in the circuit during overheating is compensated in the expansion tank. Therefore, it is impossible to directly connect a solid fuel boiler to a closed circuit.

For the joint operation of a gas and solid fuel boiler, a multi-circuit heating system has been developed, which consists of two independent circuits.

The gas boiler circuit operates on radiators and on a common heat exchanger with a solid fuel boiler and with an open expansion tank. For a room in which both boilers are installed, it is necessary to fulfill the requirements for both gas and solid fuel boilers

Joint operation of solid fuel and electric boilers

For such a heating system, the principle of operation depends on the type. If it is intended for open heating systems, then it can easily be connected to an existing open circuit. If the electric boiler is intended only for closed systems, then the best option would be to work together on a common heat exchanger.

Dual fuel heating boilers

To increase the reliability of heating and to eliminate interruptions in the operation of the heating system, dual-fuel heating boilers operating on different types of fuel are used. Combination boilers are made only in the floor version due to the rather large weight of the unit. The universal unit can have one or two combustion chambers and one heat exchanger (boiler).

The most popular scheme is the use of gas and firewood to heat the coolant. It should be borne in mind that solid fuel boilers can only work in open heating systems. To realize the advantages of a closed system, an additional circuit for the heating system is sometimes installed in the universal boiler tank.

There are several types of dual-fuel combined boilers:

1. gas + liquid fuel;
2. gas + solid fuel;
3. solid fuel + electricity.

Solid fuel boiler and electricity

One of the popular combined boilers is a solid fuel boiler with an electric heater installed. This unit allows you to stabilize the temperature in the room. Thanks to the use of heating elements, such a combined boiler has acquired a lot of positive qualities. Consider how the heating system works in such a combination.

When the fuel is ignited in the boiler and when the boiler is connected to the electrical network, the heating elements immediately begin to work, which heat the water. As soon as solid fuel flares up, the coolant quickly heats up and reaches the temperature of the thermostat, which turns off the electric heaters.

The combi boiler runs on solid fuel only. After the fuel burns out, the water begins to cool in the heating circuit. As soon as its temperature reaches the thermostat threshold, it will turn on the heating elements again to heat the water. Such a cyclical process will maintain a uniform temperature in the rooms.

To optimize the heating circuits, heat accumulators in heating systems were invented, which are a large volume tank from 1.5 to 2.0 m3. During the operation of the boiler, a large volume of water is heated from the pipes of the circuit passing through the accumulator tank, and after the boiler stops working, the heated water slowly releases heat energy to the heating system.

Heat accumulators allow you to maintain a comfortable temperature for quite a long time.

In order to avoid critical situations in winter, reduce heating costs and ensure its reliability, many owners prefer either installing a system with two boilers using different fuels, or installing. These heating options have certain advantages and disadvantages, but they fully provide their main task - stable and comfortable heating.

In order to save money, it is often used to connect two boilers to one heating system. When purchasing several thermal devices, you should know in advance what methods exist for connecting them together.

Since the wood boiler operates in an open system, it is not easy to combine it with a gas heater that has a closed system. With an open-type piping, the water is heated to a temperature of one hundred degrees or more at the highest high pressure. To protect the overheating of the liquid, an expansion tank is placed.

Part of the hot water is discharged through open-type tanks, which helps to reduce the pressure in the system. But the use of such trigger tanks sometimes causes oxygen particles to enter the coolant.

There are two ways to connect two boilers into one system:

• parallel connection of a gas and solid fuel boiler together with safety devices;
• serial connection of two boilers of different types using a heat accumulator.

With a parallel heating system in large buildings, each boiler heats its own half of the house. The serial combination of a gas and wood-burning unit form two separate circuits, which are combined with a heat accumulator.

The use of a heat accumulator

The heating system with two boilers has the following structure:

• a heat accumulator and a gas boiler are combined with heating appliances in a closed circuit;
• energy flows from the wood-burning heater to the heat accumulator, which are transferred to a closed system.

With the help of a heat accumulator, it is possible to carry out the operation of the system simultaneously from two boilers or only from a gas and wood-burning thermal unit.

Parallel closed circuit

To combine the systems of a wood and gas boiler, the following devices are used:

• safety valve;
• membrane tank;
• manometer;
• air vent valve.

First of all, shut-off valves are mounted on the pipes of two boilers. A safety valve, a device for venting air, and a pressure gauge are installed near the wood-burning unit.

A switch is placed on the branch from the solid fuel boiler for the functioning of the turnover of the small circle. Fix it at a distance of one meter from a wood-burning heater. A non-return valve is added to the jumper, blocking the access of water to part of the circuit of the evacuated solid fuel unit.

The return flow is connected to the radiators. The return flow of the coolant is separated by two pipes. One is connected through a three-way valve to the jumper. Before branching these pipes, a tank and a pump are mounted.

A heat accumulator can be used in a parallel heating system. The scheme for installing the device with such a connection consists in connecting return and supply lines, supply and return pipes to the heating system to it. For the joint or separate operation of the boilers, valves are installed at all system nodes that block the flow of the coolant.

It is possible to combine two heaters using manual and automatic control.

Connection with manual control

Turning on and off the boilers is carried out manually due to two taps on the coolant. The binding is carried out using shut-off valves.

Expansion tanks are installed in both boilers, which are used simultaneously. Experts recommend not to completely cut off the boilers from the system, but simply connect them to the expansion tank at the same time, blocking the movement of water.

Connection with automatic control

A non-return valve is installed for automatic adjustment of two boilers. It protects the shutdowns of the heating unit from harmful flows. Otherwise, the method of coolant circulation in the system is no different from manual control.

In an automatic system, all main lines must not be blocked. The pump of the working boiler drives the coolant through the non-working unit. Water moves in a small circle from the place where the boilers are connected to the heating system through an idle boiler.

In order not to consume most of the coolant for an unused boiler, check valves are installed. Their work should be directed at each other so that the water from the two thermal equipment is directed to the heating system. Valves can be put on the return flow. Also, with automatic control, a thermostat is needed to regulate the pump.

Automatic and manual control is used when combining different types of heaters:

• gas and solid fuel;
• electric and wood;
• gas and electric.

It is also possible to connect two gas or electric boilers to one heating system. Installing more than two connected thermal units leads to a decrease in the efficiency of the system. Therefore, more than three boilers are not connected.

Benefits of a Dual Boiler System

The main positive aspect of installing two boilers in one heating system is the continuous support of heat in the room. A gas boiler is convenient in that it does not need to be constantly serviced. But in case of emergency shutdown or in order to save money, a wood-burning boiler will become an indispensable heating supplement.

The heating system of two boilers allows you to significantly increase the level of comfort. The advantages of a dual thermal device include:

• choice of the main type of fuel;
• the ability to control the entire heating system;
• increasing the operating time of the equipment.

Connecting two boilers to one heating system is the best solution for heating buildings of any size. Such a solution will allow you to continuously keep warm in the house for many years.

Two boilers in one house is the key to the reliability of your heating system. It is very good if the second boiler is an alternative, for example, to gas. A gas boiler provides comfort (it does not require frequent maintenance), and a solid fuel boiler is installed to reduce heating costs and as a backup in case of an emergency. Under certain conditions, they can be combined in one system. You can look at link an interesting video that shows two main ways to implement such a solution, or below is a brief summary and description of two ways to connect boilers into one system:

The first of the ways the implementation of such a solution is the use of a hydraulic separator or a hydraulic switch in the boiler piping scheme. This simple device serves to equalize temperatures and pressures in the heating system and allows you to combine two or more boilers into one system and use them both separately and in cascade - together.

One of the solutions for coordinating the operation of two heating units and heating system circuits

Hydraulic arrow (hydraulic separator) for connecting 2 boilers

Second option coordination of the operation of two boilers can be used in systems of low power and, for example, with a double-circuit gas heating boiler. Everything is simple here: two boilers are connected in parallel to each other, the circuits are separated from one another by check valves, while two boilers can work in one combination either separately or simultaneously.

The installation of a heating system in a private house begins with the installation of a boiler. In many suburban settlements there is no gas pipeline with natural gas. Instructions on how to properly connect a solid fuel boiler will alleviate this problem.

Necessary conditions for the correct connection of a solid fuel boiler to the heating system

1. The room for the boiler room is selected separately. An area of ​​​​about 7m 2. A boiler room in a separate building is ideal. Loading fuel into the boiler room can be facilitated. It is enough to install a so-called chute in the area of ​​the receiving hopper from the outside where, for example, coal will be unloaded. Having unloaded the fuel into the receiving bunker, the coal is poured down the slope into the boiler house independently.
2. Position the heating boiler preferably below the 0 mark of the floor. This installation option of the boiler ensures ideal circulation of the coolant in the heating system without the use of a circulation pump.
3. The base for the boiler must be made of a concrete pad with an even top layer. The thickness of the concrete screed is 10 cm. The area of ​​​​the base under the boiler must be 20 cm larger than the dimensions of the connected boiler. From the side of the firebox 40-50 cm.
4. According to the norms of SNiP and fire requirements of the NPB, the distance between the boiler and the wall is 50 cm. From the side of the furnace hole, furnace, to the opposite wall, the distance is at least 1.3 m.
5. The installed heating boiler must not have gaps between the base and the body.
6. It is necessary to connect the boiler to the heating system with a steel pipe at least 1 meter long at the inlet and outlet of the pipeline. It is wrong to connect the boiler to the heating system with copper and polymer pipes.

Below is a diagram of the correct connection of a solid fuel boiler.

There are many connection methods. Consider one of the simple and reliable ways to connect.

A safety group is installed from the boiler on a direct pipeline. After the safety group, a tee for the bypass is installed. Further, the supply is connected to the wiring of the heating system. Having given up its heat in the heating system, the coolant returns to the boiler through the return pipe. To avoid the main disease in the operation of solid fuel boilers, condensate, which adversely affects the integrity of the boiler, a thermostatic three-way valve is mounted, connected to the return line on the bypass, set to a temperature of 50-60 ° C. When heated, the coolant circulates through a small circuit through a three-way valve. A temperature of 55°C prevents the formation of condensate on the inner walls of the boiler. After the three-way thermostatic valve, a circulation pump is mounted. As soon as the return temperature reaches 55 ° C, the three-way valve opens, and the heated coolant rushes into the heating circuit to the radiators.

Connecting a solid fuel boiler paired with a gas boiler, diagrams and features

The scheme for connecting a solid fuel boiler in parallel with a gas boiler differs from the installation of two solid fuel boilers. The requirements for the boiler room also differ, where the main condition is air exchange:

• The area of ​​​​a boiler room with a gas boiler, according to the recommendations of the fire authorities and the gas service, is calculated as follows: 1 kW of power - 0.2 m 3 with a ceiling height of 2.5 m, but not less than 15 m 3.
• A boiler room with a gas boiler must be equipped with a window with a window, the size of which is 0.03 m 2 per 1 m 3 of the volume of the room.
• The entrance door of the boiler room must go only to the street. Door width at least 80cm.

Gas boilers are available in two versions. Floor and wall. The requirements for installing a floor gas boiler are the same as for a solid fuel boiler. The length of the pipe connecting the chimney and the boiler is not more than 25 cm. If the boiler is coaxial, the pipe for the removal of combustion products is installed at an angle of -3 °. Otherwise, a separate pipe made of ceramic or lined with stainless steel with a hatch for removing combustion products is required for a gas boiler, and a tee with a tap to remove condensate is installed in the lower part of the pipe.

Gas and solid fuel boilers are connected in parallel to the heating system in several ways. The schemes are different, it is not necessary to know all of them, it is enough to understand the features that must be considered when using such a combination of boilers in relation to your room:

1. Efficient use of the heat exchanger. It will separate the open heating circuit and the closed one. Connect the boiler to one of the circuits, and connect the second boiler to the second circuit. A solid fuel boiler, capable of raising the temperature of the coolant to 115 ° C, heats the secondary closed circuit to which the gas boiler is connected. The gas boiler is adjusted to a temperature of about 50-60 ° C. The solid fuel boiler will take on the main load. As the fuel burns out, the gas boiler will automatically turn on, which heats the secondary circuit of the heat exchanger. The secondary circuit is equipped with a diaphragm expander. The closed expansion tank protects the radiators from overpressure. With such a scheme of a connected solid fuel boiler, it is possible to install an open expansion tank directly in the boiler room under the ceiling.
2. The use of a hydraulic arrow for parallel connection of boilers is mainly used in houses with a large area. The principle of operation of this system is as follows. The heating solid fuel boiler is installed first with a circulation pump, for example, 25/60 installed on the return pipe. An MD solenoid valve is mounted on the pipe between the boiler and the pump, which regulates the circulation of the boiler. Mandatory installation of an adjusted safety valve in the supply line. Shut-off valves are not installed at the supply. The gas boiler is installed second. Through the tee, the boiler is connected through the supply pipe to the pipe from the solid fuel boiler and then connected to the hydraulic arrow. Shut-off valves are not installed on the arrow. On the second boiler, a pre-set safety valve is mounted on the supply. A closed expansion tank is installed from the hydraulic arrow on the return pipe to the tee. Then, through a tee on the pipe, it is connected first to the gas boiler with the installation of a circulation pump of less power than that of the first boiler. After the pump, a valve without a servomotor is installed. Further, a solid fuel boiler is connected from the tee on the return pipeline. The use of a collector after the hydraulic switch allows you to assemble several heating circuits with pump groups on each of them. Collectors create the opportunity to configure each circuit individually according to the loads on the heating devices.
3. Another method of parallel connection of boilers, when a solid fuel heating unit is installed first, a gas one is installed second, and between them a flap valve is installed on the supply pipe, operating in the direction from the first heating unit. Before the non-return valve, a bypass is installed, connected to a three-way thermostatic valve set to a temperature of 55 ° C. Between the thermostatic valve and the boiler, a circulation pump of greater power than in a gas one is installed on the return pipeline. The gas boiler is connected through a tee on the supply pipeline to the solid fuel boiler and then the supply pipeline goes to the radiators. The return pipeline from the radiators through a tee is first connected to the gas boiler. After the tee, it is necessary to install a spring check valve at the boiler. With simultaneous operation of both boilers, it is necessary to adjust the temperature regime on the boilers. The gas boiler is set to 45°C. The solid fuel boiler is adjusted to a temperature of 75-80°C. Priority will be given to solid fuel. In the process of fuel combustion and temperature decrease in the first boiler, the gas boiler will turn on automatically and will maintain the set temperature in the house.
4. The use of a buffer tank. The heat accumulator is a large steel insulated container, the task of which is to keep the heated coolant from the boiler. The maximum load occurs during the combustion of fuel in a solid fuel boiler. For the efficient operation of the heating system, the heat accumulator performs one of the main tasks. But there are big downsides to this scheme. In order to heat the radiators to the desired temperature, it takes from 2 to 4 hours. This is where the gas boiler plays its main role. Let's take a look at the installation diagram. The solid fuel boiler is tied in the traditional way. A safety group is installed in front of the bypass on the supply pipe. Then a bypass is installed through the tee. Further, the supply pipeline is connected to the storage tank. The bypass is connected to the return pipe through a thermostatic three-way valve set to 55°C. Then, a circulation pump is installed, working towards the boiler, and then the pipeline is connected to the boiler. A working circuit is created, and the coolant in the heat accumulator begins to gradually heat up. From the storage tank, the supply pipeline goes to the heaters. A three-way valve is installed on it, going to the bypass. From the other outlet of the three-way valve, a circulation pump is mounted on the supply pipe.
   

After the pump, a flap valve is installed, working towards the radiators. Further, through the tee, the supply from the gas boiler is connected with the supply from the battery. After completing these works, the direct pipeline is connected to the distribution of the heating system. From the heating system, the return pipeline is connected through a tee to the gas boiler with the obligatory installation of a spring check valve operating towards the gas boiler. A closed expansion tank cuts in front of the tee, providing protection for the heating system. After the tee, through which the gas boiler is connected on the return, the return pipeline goes to the heat accumulator and is connected to the bypass from the supply pipeline also through the tee. After connecting to the bypass line, the return pipe is connected to the storage tank. This scheme allows you to quickly heat the heating system. Further operation of the system is designed for the priority of the operation of a solid fuel boiler.

Joint operation of a solid fuel boiler paired with an electric

The connection diagram of a solid fuel boiler in parallel with an electric boiler is described in detail and questions in the video:

Coordinated operation of solid fuel, gas and electric heating boilers

If desired, using a fairly simple connection scheme, you can combine the work of 3 or more different types of heating boilers in addition to solid fuel, which still remains the most acceptable and economical in terms of the consumption of kindling resources.