Connecting a solid fuel and gas boiler into one system. Piping a boiler room with two boilers Parallel operation of a gas and solid fuel boiler

The creation of a heating circuit, in which two boilers in the heating system operate either individually 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 taken into account.

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, resulting in a heating system with two boilers, can be implemented quite simply. Both serial and parallel connection are possible. In this case, parallel connection is preferable, because you can leave one boiler running while the other is completely stopped, turned off or replaced. Such a system can be completely closed, and ethylene glycol can be used as a coolant for heating systems or.

Combined 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 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 an open expansion tank. For the room in which both boilers are installed, it is necessary to meet the requirements for both gas and solid fuel boilers

Combined operation of solid fuel and electric boilers

For such a heating system, the operating principle depends on the type. If it is intended for open heating systems, then it can be easily 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 avoid interruptions in the operation of the heating system, dual-fuel heating boilers are used, operating on different types of fuel. Combination boilers are manufactured only in a floor-standing version due to the fairly large weight of the unit. A universal unit may 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 taken into account that solid fuel boilers can only operate in open heating systems. To realize the advantages of a closed system, an additional circuit for the heating system is sometimes installed in the tank of a universal boiler.

There are several types of dual-fuel combi boilers:

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

Solid fuel boiler and electricity

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

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

The combination boiler runs only on solid fuel. 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. This cyclic process will help maintain a uniform temperature in the rooms.

To optimize heating circuits, heat accumulators in heating systems were invented, which represent a large volume capacity from 1.5 to 2.0 m3. During operation of the boiler, a large volume of water is heated from the circuit pipes passing through the storage tank, and after the boiler stops operating, the heated water slowly releases thermal energy into 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 to either install a system with two boilers using different fuels, or install. These heating options have certain advantages and disadvantages, but they fully provide their main task - stable and comfortable heating.

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

Since a wood boiler operates in an open system, it is not easy to combine it with a gas heating device, which has a closed system. With an open type piping, the water is heated to a temperature of one hundred degrees or higher at the highest high pressure. To protect the liquid from overheating, an expansion tank is installed.

Some of the hot water is discharged through open tanks, which helps lower the pressure in the system. But the use of such drain 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;
• series 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 sequential combination of a gas and wood-burning unit forms two separate circuits, which are combined with a heat accumulator.

Application of a heat accumulator

A heating system with two boilers has the following structure:

• the heat accumulator and gas boiler are combined with heating devices in a closed circuit;
• Energy flows flow from the wood-burning heating device to the heat accumulator, which are transferred to a closed system.

Using a heat accumulator, you can operate the system simultaneously from two boilers or only from a gas and wood heating unit.

Parallel closed circuit

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

• safety valve;
• membrane tank;
• pressure gauge;
• air vent valve.

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

A switch is placed at the branch from the solid fuel boiler to operate the small circle circulation. Fix it at a distance of one meter from the wood-burning heating device. A check valve is added to the jumper, blocking the access of water to part of the circuit of the evacuated solid fuel unit.

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

In a parallel heating system, a heat accumulator can be used. The installation diagram of the device with this connection consists of connecting to it the return and supply lines, supply and return pipes to the heating system. For joint or separate operation of boilers, taps are installed on all system units to shut off the flow of coolant.

You can combine two heating devices using manual and automatic control.

Manual connection

The boilers are turned on and off manually using two coolant taps. The piping is carried out using shut-off valves.

Expansion tanks are installed in both boilers and are used simultaneously. Experts recommend not completely cutting off the boilers from the system, but simply simultaneously connecting them to the expansion tank, blocking the flow of water.

Automatic connection

A check valve is installed to automatically regulate the two boilers. It protects the heating unit from harmful flows during shutdowns. Otherwise, the method of circulating coolant in the system is no different from manual control.

In an automatic system, all main lines should not be blocked. The working boiler pump 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 the idle boiler.

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

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

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

You can also connect two gas or electric boilers to one heating system. Installing more than two connected heating units results in reduced system efficiency. Therefore, more than three boilers are not connected.

Advantages of a two-boiler system

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

The heating system of two boilers can significantly increase the level of comfort. The advantages of a double thermal device include:

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

Connecting two boilers into one heating system is the best solution for heating buildings of any size. This solution will allow you to continuously maintain heat in the house for many years.

Modernizing the heating system in a private home may require installing two boilers at once, connecting them into a common network. What sequence should be followed? How to connect two boilers into one system, which must be taken into account if there is a need to share a gas boiler with a solid fuel, electric boiler or heating equipment running on liquid fuel.

How to connect two boilers together?

I would like to clarify right away that simply connecting two boilers using different types of fuel into one system is one of the possible solutions to the problem of the lack of power of the installed equipment. It is also possible to connect more than two models into one network.

For what purposes may it be necessary to connect two boilers into one system? There are several good reasons why this is advisable.

1. Lack of power. Incorrect calculation of equipment or additionally added living space can lead to the fact that the boiler power may simply not be enough to maintain normal coolant temperature.
2. Increased functionality. It may be necessary to connect two boilers to one system in order, for example, to increase the battery life of the equipment. For example, if the main source of heat is a solid fuel boiler, then for its operation it is necessary to constantly add firewood, which is not always convenient, much less practical.
   By installing an electric boiler or gas heating device after it, you can solve this situation as follows. As soon as the firewood or coal has burned out and the coolant has begun to cool, additional heating equipment is switched on in the process and continues to heat the room until the owner adds a new batch of firewood in the morning.

As you can see, connecting two heating boilers using different types of fuel is practical; in addition, it may be due to an urgent need associated with a lack of equipment performance.

How to connect two gas boilers in parallel

There are two connection schemes for gas and any other water heating equipment. You can connect two boilers to one heating system:

• Sequentially - in this case, one unit will be installed after another. In this case, the load will be distributed unevenly, since the main boiler will constantly operate at full capacity, which can lead to its rapid failure.
• Parallel. In this case, the heated area will be divided into two parts. Heating will be carried out by two installed boilers at once. Parallel connection of two gas boilers is usually used in cottage houses and buildings with a large heated area.

For parallel connection, it is necessary to install a controller and also develop a cascade control circuit. Only a competent specialist can answer the question of how to connect two gas boilers in each specific case.

How to connect two boilers - gas and solid fuel?

Combining gas and solid fuel boilers into one system is a simpler task, for which it is necessary to take into account the main features that distinguish the operation of these two types of equipment.

Models of gas and solid fuel equipment can be installed in one network sequentially. In this case, TT boilers will play the role of the main source of heat supply.

The principle of their operation will be that gas equipment will be turned on for heating only if the operation of the main unit for some reason becomes impossible. Also, usually a gas boiler is assigned the task of heating water, of course, if such a function is provided. During the design of such a system, these features must be taken into account.

It will also be necessary to coordinate the chosen scheme in the gas sector and obtain all the necessary permits there, including technical conditions and connection design.

How to combine gas and liquid fuel boilers

For safety reasons, for such a connection it is necessary to create conditions under which safe operation of two types of equipment at once is possible. To do this you need to do the following:

• Install a general system for monitoring the operation of water heating equipment. The combined use of liquid fuel and gas boilers implies the installation of common automation. It, in turn, is connected to control sensors, which send a signal to turn on if the main heat source stops working.
• Install control valves. Shut-off valves operating in automatic mode can also be used.

The connection is carried out in a serial or parallel manner depending on the customer's needs. The plan and schematic diagram are drawn up in the design department, after which it is agreed upon by the gas service.

Advantages of installing several boilers on one network

Connect two boilers at the same time: floor-mounted and wall-mounted boilers may be needed if the area of ​​the room has increased sharply as a result of construction work. Even if the equipment was initially purchased with a power reserve, it may not be enough to heat additional rooms of a larger area. In this case, an additional boiler is installed, connected to the general heating system. The advantage of this solution is:

1. Possibility of simultaneous control over the operation of all equipment.
2. Savings due to the choice of the main type of fuel.
3. Possibility of longer operation of equipment.

Practice shows that it is possible to simultaneously install two or more boilers in one network. With each additional element, overall performance and efficiency drops significantly. Therefore, the feasibility of simultaneous installation of four or more units of water heating equipment is completely absent.

A good option are 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 obtain 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 down. If the gas-firewood device breaks down, the system stops working and the room will be cold.

Difficulties in using two boilers in one system

The main difficulty is that gas boilers for a private home must operate in a closed system, while the safest for solid fuel devices is an open one. is in demand because the boiler can heat water to 110 °C or more, raising the pressure above permissible limits.

It can be lowered by reducing the intensity of combustion. But the effect will be visible when the coals burn completely. Even when burning low, they are very hot and continue to heat the water, increasing the pressure.

In such a situation, you need to relieve pressure. Copes with this task open type expansion tank. When its volume is not enough, water is discharged into the sewer through a pipe installed between the tank and the sewer. This tank allows air to enter the coolant. This is bad for the internal elements of the gas boiler, pipes, etc. Solutions to the problem:

1. A combination of a closed and open heating system using a heat accumulator.
2. Organization of a closed system for a wood or pellet boiler using a special safety group. In this case, two units are connected in parallel and operate both in pairs and separately.

Read also: Manufacturing of the Kholmov boiler

Connection with heat accumulator

The idea of ​​using a heat accumulator lies in the following nuances:

1. A gas boiler receiving gas from a cylinder and heating devices form one closed system. It includes a heat accumulator.
2. Gas-generating boilers using 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 harness with your own hands you need to have:

1. Open expansion tank.
2. A hose that will be located between the tank and the sewer.
3. Shut-off valves (13 pcs).
4. Circulation pump (2 pcs).
5. Three way valve.
6. Filter for water purification.
7. Pipes made of steel or polypropylene.

The circuit can operate in four modes:

1. From a wood-burning boiler with degrees transferred through a heat accumulator.
2. From the same boiler with bypass of the heat accumulator (the gas device will be turned off).
3. From a gas boiler that can receive gas from a cylinder.
4. From both boilers.

Organization of an open system with a heat accumulator

1. Do-it-yourself installation of shut-off valves on two fittings of a wood-burning boiler.
2. Connecting the expansion tank. It must be placed so that it is higher than all the trim elements. The pressure under which a solid fuel boiler supplies water often exceeds the pressure under which coolant is supplied from a gas boiler connected to the cylinder. To equalize these values, you need to correctly configure the open expansion tank.
3. Installation of taps on the pipes of the heat accumulator.
4. Connection and boiler with two pipes.
5. Connecting two tubes to pipes located between the heat accumulator and the boiler. They are installed near the taps, which are located near the battery fittings, or at a short distance from the shut-off 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.
6. Jumper insert. It connects the supply and return pipes located between the wood-burning boiler for the home 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. Afterwards, the water will move in a large circle through the heat accumulator.
7. Connecting the filter and pump. 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 a path along which the coolant will move in the event of a lack of electricity.

Read also: Installing a heating boiler in a private house

Closed system with heat accumulator

There is no need to connect a device similar to an expansion tank because the gas boiler connected to the network or cylinder already includes a diaphragm expansion tank and also a safety valve.

To make this diagram correctly, you need:

1. Connect a tap and a pipe to the supply fitting of the gas device, which will be suitable for the heating radiators.
2. Install a circulation pump on this pipe in front of the heating devices.
3. Connect heating devices with your own hands.
4. Take a pipe from them that will go to the boiler. At its end, at a short distance from the gas unit, which is powered by a gas cylinder, you need to install a shut-off valve.
5. Connect two tubes to the supply and return lines, which will approach y. The first must be connected before 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 group security. Instead of an open expansion tank, a closed membrane one is installed in a special room.

The security group consists of:

1. Air bleed valve.
2. Safety valve to reduce pressure.
3. Pressure gauge.

The binding is done according to this scheme:

1. Shut-off valves are installed at the outlets of the heat exchangers of both boilers.
2. A security group is installed with your own hands on the supply line that departs from. The distance between it and the valve may be small.
3. Connect the supply pipes of both boilers. In this case, before connecting, a jumper is inserted into the line that extends from the solid fuel boiler for the home (to organize a small circle). The insertion point can be located at a distance of 1-2 m from the boiler. A check valve is installed at a short distance from the jumper. If the wood boiler stops working, the coolant under pressure created by the gas cylinder-operated unit will not be able to move along the supply line towards the solid fuel device.
4. The supply line is connected to heating radiators located in different rooms and at different distances from each other.
5. Install the return line. It should be located between the batteries and boilers. In one place it is divided into two pipes. One of them will fit the gas boiler. on her a spring return valve is installed in front of the unit. The other pipe must be suitable for the solid fuel boiler. The above jumper is connected to it. A three-way valve is used for connection.
6. Before branching the return line, it is worth installing a membrane tank and a circulation pump.

Connecting solid fuel into one system solves the fuel issue for the owner. A single-fuel boiler is inconvenient because if you do not replenish supplies in a timely manner, you may be left without. Combination boilers are expensive, and if such a unit breaks down seriously, all the heating options provided in it will become unfeasible.

Using a heat accumulator

The diagram for connecting a gas and solid fuel boiler into one system looks like this: the gas boiler, heat accumulator and heating devices are combined into a common closed circuit, and the solid fuel unit transfers all the energy to the heat accumulator, from which the coolant is already supplied to the closed system.

Such a network can operate in several modes:

• from two boilers simultaneously;
• only from gas;
• only from solid fuel through a heat accumulator;
• from solid fuel, bypassing the heat accumulator, with the gas boiler turned off.

How to connect two boilers to one heating system using this diagram. Shut-off valves are installed on the nozzles of the wood-burning boiler. An open expansion tank is installed at the highest point of this circuit and connected to the boiler supply pipe. Next, taps are cut into the supply/return pipes of the heat accumulator and connected with pipes to the rest of the circuit.

So that the boiler can be used without a heat accumulator, two pipes are cut in near the shut-off valves of the latter and shut-off valves are installed on them. The supply and return pipes are connected by a bypass: the supply jumper is attached to the supply by a fitting or welding, and to the return - through a three-way valve.

Between the three-pass valve and the boiler, a circulation pump with a filter is built into the circuit. It is also recommended to make a bypass in this area around the pump: if the electricity is turned off, the coolant will be able to move due to natural circulation.

Installation of the “gas” circuit is carried out as in a conventional circuit with a heat accumulator. An expansion tank with a safety valve is usually already included in the boiler design. A pipe leading to the heating appliances is connected to the supply pipe through a shut-off valve. The return line is also connected to the boiler through a shut-off valve. The pump is installed on the return pipe.

Jumpers are connected from both pipes to the heat accumulator: one - in front of the circulation pump, the second - in front of the heating devices. In these same places, connect the tubes that were installed in the primary circuit (for the movement of coolant from the boiler TD without a heat accumulator). All new connections are equipped with valves to shut off the flow.

Parallel closed circuit

How to connect a solid fuel boiler in parallel with a gas one?

In this case, a closed membrane tank and safety devices are used:

• air vent valve;
• safety valve (to normalize pressure);
• pressure gauge

Installation begins with the installation of shut-off valves on the supply/return pipes of both units. A safety group is installed at the supply of the TD boiler at a short distance from it.

When connecting a solid fuel boiler and a gas boiler in one system, on a branch from the TD unit, 1-2 meters from it, install a jumper to create a small circulation circle. The jumper is equipped with a check valve to prevent water from entering the “wood” part of the circuit if the solid fuel boiler is turned off.

The supply and return lines are carried out to the radiators. The return line branches into two pipes: one goes to the gas boiler, the second is connected to the jumper through a three-way valve. A closed membrane tank and a pump with a filter are installed in front of this branch.

The parallel scheme also does not exclude the use of a heat accumulator: supply and return pipes from both units are connected to it, and a direct and return line to the heating devices leaves from it. All components of the system are equipped with taps to shut off the flow, so that the boilers can be used both together and separately.

This is the same answer to the question of how to connect solid fuel and gas boilers into one system if not only heating is required, but also hot water supply: purchasing a double-circuit boiler when you already have one is irrational (). It is better to use a second single-circuit () and a buffer capacity.

Video about how to connect solid fuel and gas boilers to one heating system.