Connecting a double-circuit gas boiler to a heating system: requirements and standards + installation stages

Gas equipment of the boiler + water heater type is a suitable solution for owners of apartments and private houses: heat is provided, hot water is available, and it is economical. And connecting a double-circuit gas boiler to the heating system is not as complicated as it seems. But before embarking on the implementation of such a project, it would be a good idea to familiarize yourself with the theory, don’t you agree?

In this publication, we will talk about the features of the connection process: what requirements of service organizations need to be taken into account and what technical nuances of installing wall and floor models should be paid special attention to. We will supplement the presented material with visual photos and videos, which will help you complete all the work as quickly as possible and without errors.

Equipment installation rules

Installation and connection of the boiler to the system should begin after passing the design stage, when a place in the house has been prepared for the unit. If you install it in violation of the requirements, the specialists of the gas distribution company will not connect the equipment to the gas main.

General requirements at the design stage

The basic standards for installing gas equipment are prescribed in SNiP 42-01-2002. Supporting information is also contained in the already invalid, but useful SNiP 2.04.08-87.

Usually all the rules are taken into account by the design engineer, but it is also useful to know them for yourself. The room for the boiler can be a kitchen if the power of the device ranges up to 60 kW. A separate or attached combustion chamber is relevant for units with a power rating of up to 150 kW.

Additional standards for the installation of gas equipment are given in SNiP on boiler installations, as well as on heating, ventilation, and air conditioning

The premises requirements are as follows:

1. The minimum room height is 2 m, volume is 7.5 m³. If there are two or more gas appliances, the parameters change to 2.5 m and 13.5 m³ respectively.
2. Not suitable for installation: basements, balconies, bathrooms, corridors, rooms without windows.
3. The walls of the room must be covered with non-flammable materials or protected with special panels.
4. Lighting: at 10 m³ rooms are at least 0.3 m² window. In the event of a gas explosion, the windows are an easily removable structure, which increases safety of equipment operation.
5. It is necessary to have grounding and a cold water pipeline.
6. The cross-section of the chimney corresponds to the power of the installed equipment.
7. The space left around the device is: in front - from 1.25 m, on the sides (if maintenance is necessary) - from 0.7 m.
8. The distance from the vertical chimney to the unit is maintained - no more than 3 m.

Ventilation must also be provided. Natural is calculated at the rate of 3 room volumes per hour. When organizing a supply air system, combustion air is added to this value (the parameter is indicated in the boiler passport).

The requirements apply not only to premises. The distance from the attachment to the nearest structures is also regulated.This information is indicated by the manufacturer in the equipment instructions.

If a double-circuit boiler is installed on a wooden wall, a sheet of roofing steel (0.8 - 1 mm) or a mineralite slab is attached to it. If the equipment is not located in the kitchen, asbestos is also possible

Floor-standing boiler models are installed on non-combustible bases. If the surface is wooden, a metal backing is required.

It is recommended to place the device as close to the gas pipe as possible. The use of special hoses is acceptable, but they should not be very long. Bellows hoses up to 5 m are available on sale; they are allowed for installation, but according to European standards, the length is limited to two meters.

Documentation preparation process

After a general familiarization with how to technically correctly connect double-circuit gas boilers, you can begin preparing documentation. First stage - obtaining technical specifications. It is necessary to contact the regional gas service with a statement indicating the expected volume of blue fuel consumption per hour.

Technical specifications are issued in 1-2 weeks. The document is a permit to connect housing to the gas main.

The second stage - according to the technical specifications, it is developed equipment installation project. Third - statement prepared documentation by engineers of the gas distribution company.

The project includes both the installation diagram of the boiler itself and the laying of a gas pipeline from the connection point to the main line. If we are talking about a private house, a drawing of communications on the site is added

The boiler technical passport, operating instructions, certificates, and an expert opinion on the compliance of the device with all standards are submitted to the regulatory organization.The necessary papers are provided by the manufacturer of the double-circuit boiler.

Coordination of documentation can happen in a week or last up to 3 months, it all depends on the complexity of the project. In case of refusal, the inspection is obliged to provide a list of edits to eliminate the deficiencies. If all requirements are met, stamps are affixed and you can begin connecting the equipment.

Features of the wall-mounted model

First you need to make connections to the heating system, water supply and electrical network, if the device has control and regulation elements. Connection to the gas main is carried out by an employee of the relevant service or a licensed company. The home owner only needs buy a meter and gas filter.

The device has 5 connection pipes: heating system supply and return, cold water inlet and hot water outlet plus gas supply. It is convenient to screw all the fittings before hanging the device on the wall. The handles that interfere with rotation can be removed by unscrewing the nut on the rod. Installation of a gas valve cannot be done without a dielectric gasket

What products and materials will be needed during the work process:

• 3 ball valves with American sizes 1/2″ and 4 of the same size 3/4″;
• 2 mud traps (mechanical or self-flushing) - installed on the cold water supply and return of the heating pipe;
• gas filter;
• expansion tank (if its volume is not enough for a large pipeline network, a membrane tank is also needed);
• fittings for pipelines - elbows, tees;
• three-core cable (brand VVG, cross-section 2.5 mm²);
• automatic two-pole switch 20 A.

This list is suitable for heat generators of simple design with an open combustion chamber.Expensive models are equipped with an expansion tank and a gas filter.

If the water pressure is less than 1 atm, it is worth installing pressure boosting station. It is useless if the water pressure is constant within 2-3 atm.

Additionally, the system may include: a third fine cartridge filter, pressure gauges for monitoring pressure in different places of the circuit, an automatic air vent, a circulation pump, a voltage stabilizer

In the case of a separate boiler room, you will need a heating radiator, which will ensure normal temperature conditions for the boiler to operate and protect it from the formation of condensation

Next, we hang the boiler on the wall, determining the optimal height. You shouldn’t hang it from the ceiling - ease of use is important. The minimum distance from the ceiling to the outlet pipe is 15 cm, from the floor - 80 cm, from the wall - 20 cm.

To mount the device you will need two special brackets, which are supplied in the kit. They are attached to the wall with plastic dowels and screws. To set them correctly, it is recommended to use a level and plumb line.

Stage #1 - connection to the heating system

All Ball Valves to shut off the pipeline, they are installed more for servicing the system than taking into account its possible cutting and dismantling during operation. Heating equipment is characterized by reliability. Example: a shut-off valve on the heating return is designed to clean the filter without draining the coolant.

The standard connection diagram is in the passport of any double-circuit boiler. This is what you should use to navigate when tying up the device.

Recommendations for connection:

1. Half-inch taps are installed on water fittings and gas supply. And DN20 are mounted on pipes with coolant.
2. The fittings must be screwed with the pipes down.
3. The filters are attached horizontally, with the “spouts” facing the floor. In this position it is convenient to clean them.
4. The external expansion tank is connected to the return line using additional fittings.
5. The drain pipe is installed at the lowest point of the system.

If you plan to fill the system as coolant non-freezing antifreeze; to be on the safe side, additional valves for supply and return should be added to the circuit. This makes it possible to dismantle the boiler without draining the antifreeze.

Stage #2 - connecting the boiler to the electrical network

There are usually no difficulties with supplying electricity - just plug the device into an outlet. But there are also rules and safety requirements.

If the boiler is heavily dependent on electricity and its supply is often turned off in the region of installation, the circuit is supplemented with an uninterruptible power supply

The main requirement when connecting the device to the network is grounding and the presence of a circuit breaker. The latter is located so that in case of an emergency water does not get on it.

Primary requirements:

• You need a wire connected to the ground loop. If such a cord is not included in the kit, the conductor is connected to the body of the device itself.
• It is prohibited to use steel pipes of the hot water supply system as grounding conductors.
• The cable is laid in a protective “corrugation”.

When connecting turbocharged boilers from European manufacturers it is important not to confuse phase with zero. Otherwise, the electronic unit will not start the system.

Stage #3 - connecting the unit to the chimney

In 95% of modern houses, wall-mounted boilers with closed combustion chambers are installed and coaxial chimney. It is discharged horizontally through the wall with a slope of 3-5% towards the street to allow condensation to escape.

Pipe sections of several elements are mounted inside each other in the direction of the flow of combustion products. In a vertical channel, joints must be sealed

For a high-power floor-mounted unit, only a vertical design is suitable, which can cope with a large volume of combustion products. It should have as few turns as possible and protrude beyond the boundaries of the roof at a distance of 0.5 m.

Installation of a floor-standing device

If a double-circuit heat generator requires power supply, then it is connected in the same way as a wall-mounted “colleague”. The energy-independent device has a built-in copper or stainless steel coil for heating water. Apart from the burner, automation and heat exchanger, nothing is supplied with this equipment.

To install a non-volatile unit, you will need a set from the previous list plus the following system elements:

• security group, the safety valve of which is designed for the operating pressure of the boiler (data is in the passport);
• expansion tank with a volume of 10% of the total amount of coolant;
• circulation pump.

A safety group is always installed on the supply pipe next to the heating device to protect the most expensive part of the system from destruction during a sudden pressure surge.

The distance from the boiler to the device should be no more than 50 cm. Taps and tees must not be installed on the pipe section between the heater and the element; the line must be left clean

If the floor-standing device is connected to a gravity system, only an open-type expansion tank with overflow is installed. The pump and safety group are excluded from the diagram.

In this situation, pipes with a diameter of 40 mm or more are needed, which are laid at a slope of 5 mm for each linear meter of the main line. The heat generator remains at the lowest point, the tank is located at the highest.

If electricity is connected, it is permissible to organize forced circulation using a pump. In this case, its installation is carried out through a bypass

Most modern systems include circulation pump, which is effective, but dependent on electricity. When the lights are turned off, heating and water heating are turned off. It is wise to organize an alternative natural circulation method for force majeure.

Options for schemes with a boiler

When the standard power of the device of 9-13 liters is not enough to meet the needs of the residents (example: there is a bath in the bathroom), the system is supplemented with a boiler. If selected indirect heating boiler, then it is impossible to simulate the flow with an additional circulation pump, which is turned on and stopped by a thermostat signal.

An incorrect circuit leads to a problem in the form of prolonged heating of the boiler. During this time (up to 2 hours), the house is not heated and the rooms cool down. Plus, the boiler life is reduced due to the “clocking” effect and hot water entering the second circuit rather than cold. Bacteria multiply in the boiler itself.

The correct scheme is to connect an indirect boiler to the heating circuit. The thermostat is connected to the boiler automation. The DHW outlet pipes are simply plugged

In this scheme, heating between the circuits is provided by a three-way valve.The boiler loads in 20-25 minutes. The plugs do not affect the life of the heat generator.

More practical options are installing a layer-by-layer heating boiler (there are models for dual-circuit systems) or an electric storage tank. The first does not have a heat exchanger, which reduces the cost of the system. The second significantly improves the comfort of using hot water.

In a circuit with an electric boiler, check valves and safety valves are mounted on the supply pipe. The latter sometimes leaks water that needs to be disposed of. The safety valve requires manual inspection 2 times a month

In the case of an electric boiler, it is recommended to additionally install an expansion tank. And if the pressure in the system is more than 6-8 bar, you will need a pressure relief valve to reduce it.

Additional installation recommendations

Categorically it is impossible to reduce the diameter of the internal section of the connected pipes. The optimal value for a boiler up to 28 kW is at least 20 mm for heating and at least 15 mm for water supply.

If the boiler is not included in the circuit, it is wiser to install the device closer to the hot water tap, which is often used.

In case of connection heated floors, the system is complemented by a separate branch with a collector and a circulation pump.

Conclusions and useful video on the topic

The operating principle of a double-circuit boiler. Advantages and limitations of the model.

Analysis of the connection diagram of a double-circuit heat generator with recommendations on the nuances of installation.

Connecting a boiler to the system is a consequence of improper installation.

After collecting and preparing documentation, it is necessary to connect the double-circuit boiler to heating, electricity and the chimney. The devices are different, but the requirements for their installation are the same.Features of a specific model are indicated in the operating instructions.

It is wiser to entrust the first start-up of the unit to a gas service specialist. He will test the double-circuit, check all the blocks, set the modes and instruct the owner on the operation of the equipment.

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