How the gas heating boilers are carried out: schemes for single and double-circuit boilers

An effective heating system is essential for keeping your house warm and comfortable during the winter. Because they consistently provide warmth and hot water when needed, gas heating boilers are a popular option for many households. Gaining an understanding of the functioning of these boilers is crucial to guaranteeing their correct operation and optimizing their efficiency.

A gas heating boiler heats water by burning natural gas, which is then distributed throughout the house through radiators and pipes. Gas boilers come in two primary varieties: single- and double-circuit models. Every variety has a special layout and features.

Often referred to as a "heat-only" boiler, a single-circuit gas boiler is made exclusively for home heating. It warms water and distributes it to underfloor heating systems or radiators, warming various parts of the house. For homes where hot water is supplied by an independent system—such as an immersion heater or water heater—this kind of boiler is perfect.

In contrast, a double-circuit gas boiler, sometimes referred to as a "combi" boiler, provides hot water as well as heating, fulfilling two purposes. It not only heats the house but also heats water on demand, doing away with the need for an additional hot water tank or cylinder. This is a popular option for smaller homes or properties with limited space because it can save energy and space.

Both heating engineers and homeowners should be familiar with the schematics of these boilers. The boiler’s operation, including the water flow, the parts involved, and the control mechanisms, are shown in the schematics. Homeowners can diagnose potential problems with their heating system and gain a better understanding of how it works by becoming familiar with these schematics.

To sum up, gas heating boilers are essential to maintaining a warm and cozy atmosphere in our houses. Knowing how single- and double-circuit boilers operate is crucial for preserving efficiency and guaranteeing consistent warmth all year long, regardless of which type you choose.

Single-circuit boiler scheme Double-circuit boiler scheme
A single-circuit boiler heats water for either the central heating system or hot water taps. A double-circuit boiler heats water for both the central heating system and hot water taps separately.

It’s important to comprehend how gas heating boilers operate when it comes to insulation and home heating. There are two primary varieties of these boilers: single- and double-circuit boilers. While double-circuit boilers also supply hot water for showers and faucets, single-circuit boilers only heat water for your home’s heating system. In order to provide warmth and hot water when needed, both systems heat water by burning gas. The heated water then travels through pipes to radiators or faucets. Double-circuit boilers provide the convenience of hot water on demand, but single-circuit boilers are simpler and frequently less expensive. Comprehending these programs enables homeowners to make knowledgeable choices regarding their heating systems, guaranteeing year-round comfort and effectiveness.

Functions of strapping

A collection of pipes, equipment, and devices known as binding are used to move coolant to heating batteries. With the exception of radiators, the whole heat supply system is part of its structure.

Any equipment that uses gas could be hazardous. Errors in the installation process result in both explosive situations and issues with the home’s heating. It is imperative to adhere strictly to the safety regulations and standards of SNiP 41-01-2003, "Heating, ventilation, and air conditioning," when assembling a project and installing it.

The kind of installed boiler, the building’s structural and functional characteristics, and the kind of heat supply system all influence the circuit choice. The plan needs to be designed ahead of time, with the best locations for equipment installation selected and the subtleties of pipeline layout determined.

The primary component of the heat supply system is the boiler.

The strapping carries out these crucial tasks:

  1. Pressure control. With a properly arranged strapping, thermal expansion is leveled, therefore, the pressure will not reach dangerous values.
  2. Prevention of importance. Traffic jams in the pipeline are formed due to air bubbles. The heating efficiency is reduced, since the batteries do not completely heat up with a constant fuel consumption.
  3. Blocking warning. With the improper strapping of the boiler in pipes and batteries, the risk of rust and scale formation is great. The presence of even small particles in the liquid leads to contamination of the entire system. This leads to an increase in fuel consumption and, accordingly, the cost of heat supply in case of loss of its quality.
  4. Connecting additional contours. It is allowed to install a "warm floor", a cumulative boiler.

Because the strapping plan needs to be chosen and developed in advance, the way the gas heater is connected to the pipes and other components affects the quality of the heating in the house.

Choosing pipes

In order to install a gas boiler and its wiring, metal-plastic or PP-pipe should be used. Their qualities are on par with those of copper or galvanized steel, they are less expensive, and installation is fairly easy.

Metal-plastic pipes reinforced with aluminum are used to heat batteries through press-fittings or polypropylene. Absence of press-fitting sensitivity to installation quality: even the smallest placement error can result in a leak. Pipelines made of polypropylene lengthen when exposed to temperatures higher than 50°C. Pipes made of polyethylene or metal-plastic can be used to install a "warm floor."

Binding of a single -circuit gas boiler

Essential elements

These components are typically found in a single-circuit boiler’s assembly set:

  • radiators;
  • expansion tank;
  • circulation pump;
  • safety valve;
  • Air removal devices;
  • KN boiler;
  • filter-gryazevik;
  • Hydrofoil.

When the circuit pressure suddenly increases, the safety valve is intended to release an excessive amount of coolant. A drainage pipe allows the system’s excess water to be released into the sewer.

The majority of gas boiler units come with a separate tank that is intended to collect extra coolant from the heat supply circuit. 10% or so of the system’s total water or antifreeze content should be the capacity. Installing a second tank is required if the one that comes with the unit is insufficient.

The binding kit includes an air discharge to stop the circuit from outfitting after the coolant is removed.

An indirect heating boiler is installed in order to "turn" a single-circuit boiler into a dual-circuit boiler and provide hot water in addition to heating.

Together with the gas heater, the circulation pump adds to the strapping’s incapacity to generate the necessary pressure due to the pump’s inadequate power. Normally, the pump’s power requirement is between 50 and 200 W, but it can be raised if needed.

Removal using a hydraulic shotgun that has nozzles made to link extra circuits. With the element, multiple heating devices with varying coolant pressures and temperatures can be integrated into a single system.

A supply pipe is struck by the filter-gryazevik. It is intended to keep suspended particles from the heat supply system from penetrating the boiler heat exchanger, which could negatively impact the unit’s operation.

The system is put together.

The security unit combines air-outlet cranes and safety functions. It is set up on a pipe that draws heated coolant out of the heater, where the maximum values of pressure and temperature are reached. The boiler’s pump is positioned where the coolant temperature is the lowest. Anywhere along the contour, not far from the heater, is where you’ll find the expanding tank.

Such strapping techniques are employed in order to insert the gas heater system with a single contour:

  • with gravitational circulation of the coolant;
  • with forced movement;
  • together with an indirect heating boiler.

Any single-circuit boiler, regardless of brand or model, has three pipes at the bottom. They’re linked to them:

  • supply of heated coolant to the heating battery;
  • gas supply;
  • Cold heat carrier from batteries back to the boiler.

Gas boiler connection

The binding circuits for wall and floor installation apparatuses are the same.

Natural circulation

Complete energy dependence is a feature of the heat supply system using the coolant’s natural current. All that’s inside the security unit is the expansion tank. The majority of the time, a reset is mounted in front of the heat exchanger to allow the coolant to drain completely. Any sealed metal or plastic capacity may be used in place of a membrane tank.

The heating unit should be placed in the lower section of the system to allow for the natural movement of coolant at the highest point, where the expanding tank is installed. The roser is designed with a constant slope to allow coolant to freely rise to the expansion tank and then descend to the boiler. In such a scheme, the height differential between the heat exchanger and batteries creates hydraulic pressure.

The minimum pipe diameter needed to guarantee the coolant moves at the necessary speed is 32 mm.

You can also add a pump to the circuit to distribute the coolant, but in order for it to work, you must connect it to the mains. The pump is connected in line with the primary contour and is shut off by a ball or check valve. They overlap and the coolant flows freely, following the laws of gravity, when the pump is turned off.

Binding with forced circulation

The simplicity of control with this option is different. Warmth and comfort in every room are achieved at the same time as installation becomes more costly and intricate.

Binding in the system that requires forced movement

Because the heating system depends on energy, it is best to provide it with insurance so that in the event of an electrical outage, the coolant circulation can be converted to a gravitational regime.

The installation of auxiliary devices complicates the strapping scheme and necessitates routine maintenance and inspection during operation. In the absence of prior experience managing these devices, it is necessary to entice outside experts and compensate them for their services.

Plan featuring a hydraulic carrier

If the scheme needs to create multiple contours that work simultaneously, a hydraulic carrier is added. For their connection, the boiler draws 50 kW of power.

The heater can be connected using a combined scheme, which consists of primary and secondary rings, to minimize the number of devices. They all have their own circulation pump settings. In order to prevent uneven radiator heating, collectors are also added to the outline at boiler powers of less than 50 kW.

Schemes of combined types are cost-effective. especially good at warming the rooms thanks to the "warm floor," which runs off the heat returned by radiators. Energy resources are used in the most sensible way as a result.

Binding with a boiler

It must be connected to the boiler in order to guarantee a hot water supply from a single-circuit boiler. The apparatus functions as a secondary circuit and has its own heat exchanger. It is passed through a gas boiler that heats the coolant.

The BCN connection is made in parallel with the heat supply system to the feed and return pipes. The boiler tank is connected to pipes; cold water enters the device through one pipe, and hot water exits the other.

Binding of a double -circuit gas boiler


Boiler rooms include the gas double-circuit boiler type. It consists of:

  1. Heat exchangers. The main one is used to warm up the coolant, the second – for the transfer of hot water to the DIS system.
  2. Circulation pump. The device is built into the boiler, so to look for a pump suitable in power and do not need to engage in a separate installation.
  3. The tank is extensive. It is selected according to the size of the heat supply and performance of the boiler.

The principles of strapping

The double-circuit boiler is connected to five pipes, four of which are intended for the input and output of water. Gas is used on the fifth pipe, which is connected to the burner by a gas valve.

Water pipes present more challenges:

  • One connects the return system to the pipe for the first coolant;
  • The second connects the same pipe to the feed pipe on the back;
  • The third pipe is used to connect the water supply with the pipe of the secondary heat exchanger;
  • The fourth is the second pipe of the heat exchanger with a pipe for feeding heated water to the DIS system.

A boiler connection example

The boiler pipeline for the dual circuit is equipped with a three-way valve that is controlled by heater automation. Heating is turned off when the hot water is turned on.

The following is a description of the process:

  1. Redistribution of the coolant from the main heat exchanger.
  2. The three -way valve overlaps the heat supply circuit and redirects the fluid flow into a secondary heat exchanger. Cold water heats up in it.
  3. When consuming hot water, the valve is in a locking position. After closing the mixer, it automatically switches to heat supply.

The work schedule is not totally practical because there is obviously insufficient hot water produced for a large family. In this instance, there is just one water consumption point—a kitchen or shower, for instance. The boiler will not have enough time to heat the water to the proper temperature, so it will only come out as warm.

Installing a second boiler, any capacity, is the exit.

Boiler strapping with a boiler

There are always the same number of conclusions needed to connect pipes. The secondary heat exchanger closes with the boiler contour in the evolving district heating and cooling scheme.

Strapping a boilerand using a boiler

Modifications to the plan:

  • The first output of the secondary heat exchanger is connected to the input pipe of the boiler;
  • The second output is connected to the water heater.

The water heater is in direct contact with the heat exchanger’s water supply rather than being connected. Water flows out of it and into the hot water’s contour. The boiler thus approaches the same quartet of water pipes.

  1. Water water does not differ in cleanliness, which leads to rapid clogging of heat exchangers. After a year of using the boiler, they require cleaning or repair.
  2. A three -way valve does not need to switch. When the mixer is operating and the consumption of heated water, the heating system functions as usual as usual.

This plan is appropriate for homes with double-circuit boilers already installed, but insufficient hot water supply. Alternatively, you can buy a suitable boiler and integrate it into an existing scheme to avoid having to buy a single-circuit unit and redo the entire system.

Electric water heater

You can heat water in the necessary volumes and at the necessary temperature using a different method. An electric storage water heater is used for this.

The strapping scheme is essentially the same as the previous one, with a few minor differences:

  • The first output of the secondary heat exchanger is attached to cold water supply;
  • another pipe is connected to the electric heater;
  • The pipe from the water heater is assigned to the DHW system.

The boiler operates in the same manner as direct feed when the hot water crane in the kitchen or shower is turned on; a three-way valve is activated. However, the drive receives water first, and the heating element there warms up to the desired temperature.

Connecting an electric water heater

  • the constant presence of hot water for home needs in the required volume;
  • decrease in fuel consumption on water heating.

Particularly in the winter, gas heating boilers are essential to maintaining a warm and cozy environment in our homes. It is crucial to comprehend the operation of these boilers, whether they are single- or double-circuit, in order to guarantee effective insulation and heating.

The less complicated of the two boiler types, single-circuit boilers are only in charge of heating water for the central heating system. They provide warmth to the entire house by heating water and distributing it through underfloor heating systems or radiators. They might not be able to simultaneously supply hot water for household use, despite the fact that they are typically less complicated and more economical.

Double-circuit boilers, sometimes referred to as combination boilers, on the other hand, serve two purposes. They provide hot water for showers and faucets in addition to heating the water for the central heating system. Because there is no need for a separate hot water cylinder, this integrated system offers the advantages of convenience and space savings. They might, however, need more complex installation and upkeep.

It’s important to evaluate your household’s unique needs before installing a gas heating boiler. The choice between single and double-circuit boilers will depend on a number of factors, including your home’s size, the amount of hot water you require, and your budget. Additionally, optimizing the efficiency of your heating system is greatly influenced by proper insulation of your home.

Proper insulation keeps the heat produced by the boiler inside the house, minimizing heat loss and cutting down on energy use. By lowering carbon emissions, this not only lowers utility bills but also promotes environmental sustainability. Double-glazed windows, loft insulation, and cavity wall insulation are a few examples of insulation techniques that work well to keep heat in and keep interior temperatures comfortable.

In conclusion, for effective home heating, it is critical to comprehend the operating principles of single- and double-circuit gas heating boilers. Homeowners can lessen their carbon footprint and create a warm, energy-efficient living space by selecting the appropriate boiler type and making sure they have enough insulation.

Video on the topic

Wall boiler strapping errors.

Binding and installation of a double -circuit gas boiler Ariston Cares X 15 CF

Binding of a biped gas boiler Baxi.

Proper binding of a double -circuit gas boiler

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