What is a wall-mounted double-circuit gas boiler? What are double-circuit gas boilers? Double-circuit gas boiler for what

In the heating equipment market, gas-fired boilers are in great demand. At the same time, a double-circuit boiler differs significantly from a single-circuit one, and these models are used in different conditions.

For the arrangement of a residential building or apartment, it is necessary to choose such units that will be optimal in terms of reliability, quality and economy.

Types of gas boilers

Heating units have individual parameters that will help you choose the perfect option. When choosing equipment, the area of the heated room plays an important role.

Depending on this, specific models should be considered.

Single-circuit and double-circuit

Single-circuit type heaters are designed specifically for small spaces. Heating equipment is designed to heat the coolant with autonomous heating. A big advantage - wall models take up little space. The system has two important functions:

heating of a private house;
water heating.

Due to the presence of such possibilities in one device, the double-circuit boiler is in great demand and is considered the best-selling device. Its shape is compact and does not take up much space.

The cost of the unit is low, and there is no need to buy additional hot water systems.

Wall and floor

Gas heating double-circuit boilers are found in two types:

wall-mounted;
floor.

They differ in parameters, but the functions remain practically the same. Wall-mounted boilers of the double-circuit type are small in size, spacious and have a good ability to heat both housing and water. However, such a device is more suitable for an apartment or a cozy cottage.

Floor structures are large units that require installation in a separate room. The connection of the boiler itself is simple, as is the operation. Usually, floor equipment is used only for heating a large private house, where water is heated using an additional boiler.

Condensing and convection (traditional)

A double-circuit condensing boiler is a relatively new piece of equipment. The principle of operation is the deliberate formation of condensation. Moisture turns into a gaseous state, and the heat energy released in this case is spent on heating the coolant. Thus, the cost of generating energy due to fuel combustion is significantly reduced.

The convection device works according to a simple principle: how much gas is burned, so much energy is released. Unlike in this model, the release of even a small amount of moisture can damage all equipment.

With a combustion chamber of open and closed types

Heating devices with an open combustion chamber are called atmospheric burners. They have found application in boilers up to 70 kW. The heat exchanger is installed above the combustion chamber. Modern models are equipped with automation that reduces the risk of fire. Wall-mounted double-circuit boilers are equipped exclusively with atmospheric burners.

Fan burners or with a closed combustion chamber can be used to heat residential and industrial buildings. Water flows between the walls of the tank (burner). Complete flame insulation makes the device safer. A large amount of energy is expended on the operation of the fan, therefore boilers of this type will increase material costs.

But also for household / hygienic purposes. The boiler solves both problems. Consider the device of a single-circuit and double-circuit gas boiler, the pros and cons of both designs.

Features of boilers

What is the difference between a single-circuit gas boiler and a double-circuit one? A single-circuit is responsible only for heating: one or more pipelines provide radiators and / or with a coolant.

The DHW problem has to be solved separately. There are two solutions, about them below.

What does a double-circuit gas boiler mean: it is possible, using the same unit, to heat water both for heating and for household needs (). This is due to a double heat exchanger or two separate heat exchangers in the boiler structure.

Heat exchangers of double-circuit models are of flow-through and boiler type. Flow-through, as a rule, are low-power, they are suitable for houses or apartments with a small number of users.

Boiler models are supplied with a water tank with a capacity of up to 180 liters. Water in such boilers is heated both in storage and in flow mode. Running water is colder, because does not have time to heat up.

The second constructive difference between two-circuit units is the structure of the heat exchanger. The combined heat exchanger consists of two tanks of different sizes, one built into the other. The water in the internal tank, intended for the needs of hot water supply, is heated by the coolant in the external (heating) heat exchanger. In separate heat exchangers, these two tanks are located side by side.

The main thing is how a single-circuit boiler differs from a double-circuit one: the use of hot water from the boiler does not affect the heating process. In double-circuit models, DHW is priority: when hot water is required for a shower or a kitchen, the boiler switches to their maintenance, while the coolant is not supplied to the heating circuits.

The switching of the circuits is performed by a three-way valve that responds to the opening / closing of the hot tap: in the open position of the tap, the valve switches the boiler to supply hot water, in the closed position - to the heating circuit. Both circuits cannot work at the same time.

The second limitation is the number of draw-off points. The boiler operates on DHW efficiently if there are no more than two of them, and the distance to both is small. When there are two points (shower and kitchen faucet), they try to place the unit between them. With a large distance from the boiler to the hot water tap, you have to wait a long time.

Single-circuit or double-circuit heating boiler - what's the difference? The single-circuit model has only one heat exchanger, located above the burner ().

In this case, the DHW problem can be solved in one of two ways:

installation of an indirect heating boiler;
installation of a separate heating element water heater.

When using an indirect heating boiler, the principle of operation of a single-circuit boiler becomes similar to the functioning of a double-circuit: the movement of the coolant between the circuits is regulated by a special valve (). In this case, the pipeline is oriented so that, if necessary, the coolant can flow from the boiler into the heating circuit, bypassing the boiler.

Points for and against

Which is better for a private house - single-circuit or double-circuit? Both models can provide a house with hot water. In what cases is it better to prefer this or that option?

Differences between a single-circuit gas boiler and a double-circuit one:

low price. Buying and installing a single-circuit boiler will be cheaper than a double-circuit one;
heat efficiency is higher, especially if you purchase a floor-standing model (). Floor standing boilers are made of cast iron, it keeps heat longer than steel;
less required power - for the operation of the second circuit, when buying a boiler, you have to add about 25% of the power additionally;
if the problems of heating and hot water supply are solved separately (to obtain hot water, not a boiler, but a separate heater is used), an antifreeze liquid can be used instead of water in the heating circuit.

When you need to decide which is better - a single-circuit boiler with a boiler or a double-circuit one, the main advantage of the latter is taken into account - compactness. It takes up much less space than a single-circuit boiler + boiler (or an autonomous heater). This is important for a small house or apartment.

But the best application for a boiler with two circuits is a large house and a small family. The larger the house, the longer the heating circuits, the higher the inertia of the system. In a long circuit, the coolant cools more slowly than in a short circuit (this is inevitable when hot water is turned on). Accordingly, the more users, the more often it is turned on, the longer the heating is turned off.

The advantage of the dual-contour model is that the contours can be used separately. For example, heating is not needed in summer, the boiler can only operate on hot water supply.

To decide whether to choose a double-circuit gas boiler or a single-circuit boiler, you need to take into account other disadvantages of double-circuit models.:

unstable temperature, especially when there are two points of water intake. The pressure is also unstable. There may not be enough pressure or the water in the tap / shower will not be hot enough;
the DHW heat exchanger suffers from limescale deposits. Some models are difficult to clean;
antifreeze cannot be used for heating, only water;
if the family is large, the need for hot water is high. The boiler's own capacity is not enough and you still have to supplement the system with a boiler. A single-circuit boiler with a boiler or a double-circuit boiler with a boiler take up the same amount of space, it will not work to place the system in the kitchen, you will have to allocate a room for a boiler room.

Finally, a single-circuit boiler and a double-circuit boiler differ in the configuration. An additional advantage of two circuits over one is that the package usually includes everything you need: a pump, a three-way valve, an expansion tank.

A single-circuit boiler is often sold in a basic configuration: a boiler, a pump and other necessary system elements have to be purchased separately. It is easier to install a double-circuit boiler than a single-circuit boiler and a boiler.

Video about choosing between a single-circuit boiler and a double-circuit boiler.

Today, the most popular gas boiler can not only heat a house, but also prepare hot water in a flow-through mode. have firmly occupied the niche of high-quality, efficient, relatively inexpensive heating equipment and, since in our country natural gas belongs to the category of the most inexpensive fuel, this niche will not be left soon.

The range of capacities of wall-mounted double-circuit gas boilers ranges from 13 to 36 kW. This range will perfectly cope with heating a room up to 300-350 m2.

For the preparation of hot water, a gas double-circuit boiler is in no way inferior to gas water heaters in terms of comfort, speed and volume of preparation of hot water. The productivity of hot water preparation of double-circuit boilers is on average 8-12 liters per minute.

The preparation of hot water in a double-circuit boiler can take place in various ways:

via a secondary plate heat exchanger;
through a bithermal heat exchanger;
through an indirect heating boiler built into the boiler (this option is a combination of a single-circuit boiler and a boiler located in it).

What is a boiler heat exchanger and what is it for?

A heat exchanger is a device in which heat exchange is carried out between two heat carriers having different temperatures. The heat exchanger of a gas boiler is designed to transfer heat released during fuel combustion. The heat exchanger is located above the gas burner and when the gas is burned, heat is generated, which is transferred to its metal walls. Inside these walls there is a coolant that moves in a closed circuit of the heating system and transfers heat to radiators, which in turn transfer heat to the room.

Double-circuit gas boilers are divided by types of heat exchangers into two types:

boilers with a primary heat exchanger (for heating) and a secondary heat exchanger (for preparing hot water);
boilers with bithermal heat exchanger (for heating and hot water preparation)

The main function of the primary heat exchanger [Fig. 1] is to transfer heat generated from gas combustion in the burner to the heating medium of the heating system. It consists of copper pipes and copper plates. For high temperature resistance and corrosion protection, the surface of the primary heat exchanger is covered with a protective layer.

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The main function of the secondary heat exchanger [Fig. 2] is to transfer heat from the heating medium of the heat carrier to the heated medium, namely the preparation of hot water supply. This is done through thin plates, due to which the secondary heat exchanger is called plate.

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Structurally, a bithermal heat exchanger [Fig. 3] is a pipe in a pipe, on the surface of which copper plates are soldered - the fins of the heat exchanger. The inner pipe of the heat exchanger is designed for preparing hot water supply, and the outer pipe is for heating the heating medium of the heating system.

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Let us consider the options for double-circuit gas boilers with various types of heat exchangers when they work for heating the system and for preparing hot water supply.

1. Double-circuit boiler with a secondary heat exchanger when operating on a heating circuit.

A schematic diagram of the device and operation of such a boiler is shown in [Fig. 4].

Essential elements:

A - heating supply line;
B - hot water DHW;
C - cold hot water supply;
D - heating return line;
1 - gas burner;
2 - circulation pump;
3 - three-way valve;
4 - secondary heat exchanger;
5 - primary heat exchanger.

When the boiler is operating in heating mode, the gas burner (1) transfers heat to the primary heat exchanger (5). The circulation of the coolant is provided by the pump (2). A three-way valve (3) shuts off the entry of liquid into the secondary heat exchanger. Hot heating medium for the heating system leaves through the heating supply line (A) and returns to the boiler for further heating through the heating return line (D).

2. Double-circuit boiler with a secondary heat exchanger when operating on a hot water supply circuit.

A schematic diagram of the device and operation of such a boiler is shown in [Fig. 5].

When the boiler is operating for DHW heating, the three-way valve (3) shuts off the heating line (A). The hot heat carrier from the primary heat exchanger moves to the secondary heat exchanger (4). Cold water from the water supply (C) passes through the secondary heat exchanger, heats up and enters the hot water supply line (B).

3. Double-circuit boiler with a bithermic heat exchanger when working on the heating circuit.

A schematic diagram of the device and operation of such a boiler is shown in [Fig. 6].

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Essential elements:

A - heating supply line;
B - hot water DHW;
C - cold hot water supply;
D - heating return line;
1 - gas burner;
3 - circulation pump.

When the boiler is operating in heating mode, the gas burner (1) transfers heat to the bithermal heat exchanger (2). The circulation of the coolant is provided by the pump (3). Hot heating medium for the heating system leaves through the heating supply line (A) and returns to the boiler for further heating through the heating return line (D).

4. Double-circuit boiler with a bithermic heat exchanger when operating on a hot water supply circuit.

A schematic diagram of the device and operation of such a boiler is shown in [Fig. 7].

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In the boiler operating mode for hot water preparation, the gas burner (1) transfers heat to the stationary heat carrier through the bithermal heat exchanger (2), and then to the DHW circuit. At this moment, the circulation in the heating circuit is stopped, the circulation pump (3) does not work. Liquid circulation should not occur simultaneously in both circuits.

Based on the above-described principles of operation of double-circuit gas boilers, it can be concluded that the use of two separate heat exchangers is more preferable.

In the event of a sudden failure of the secondary heat exchanger, the boiler can freely operate in heating mode, and this is a very significant factor, especially during the cold season in the conditions of our winter period.

Replacing the secondary heat exchanger is also significantly cheaper than replacing the entire bithermic heat exchanger.

The disadvantage of a bithermal heat exchanger is the constant double load in the form of preparation of both hot heat carrier for the heating system and hot water supply.

The advantage of boilers with a bithermal heat exchanger is their relatively inexpensive price compared to gas boilers with two heat exchangers, as well as a larger volume of hot water preparation due to the large area of the heat exchanger (in comparison with the plate one).

Selection of goods

In addition to heating, heat generation devices in our house are designed to provide heating of water in the hot water supply (DHW) system. The consumer can choose between the two most common options for heating equipment: these are single-circuit boilers paired with a separate storage water heater (boiler) of indirect heating with a capacity of 100-300 liters or more, or combined double-circuit heating boilers.

To understand what are good and what are not very double-circuit heating boilers, their characteristics and capabilities should be compared with an alternative system: a single-circuit boiler and a boiler. It should be mentioned that manufacturers also offer heating boilers with a built-in indirect heating boiler, which are sometimes conventionally referred to as double-circuit, but they find much less use, because the volume of the boiler is small (only 15-60 liters), and the price, on the contrary, is quite high. Their only serious advantage over the option with a separate water heater is compactness.

A boiler with a built-in boiler (it is at the bottom) cannot be hung over the kitchen countertop, it is comparable in size to a refrigerator. But still it is not as bulky as a water heater for hundreds of liters.

Cons of double-circuit boilers

Let's make a reservation right away: the disadvantages listed below are inherent in double-circuit boilers to varying degrees, depending on the design of the heat exchanger. In the best (more expensive) models, they are kept to a minimum.

When using a double-circuit boiler, it is necessary to observe the predetermined balance of hot water and gas consumption. The power of the jet is limited, a decrease in the flow of hot water without gas regulation leads to a noticeable increase in its temperature.

It is recommended to use only one tap at a time, opening hot water to the set maximum (with this design, the flow is regulated and limited on the DHW line of the boiler itself), otherwise overheating may occur. If you open hot water in several taps, the temperature of the water in them can vary greatly, in the one closest to the boiler it will be too hot, in the far one it will be cold.

A large-capacity indirect heating boiler, integrated into a system with a single-circuit boiler, is capable of providing several taps with hot water without any temperature fluctuations; you can use all mixers at the same time.

When the pressure in the water supply system changes, the heating temperature (balance of water and gas consumption) of the double-circuit device will have to be re-adjusted.
DHW heat exchangers in double-circuit boilers are prone to the accumulation of salt carbonate deposits, provided that they use hard water. This can lead to a decrease in performance or even failure of the heat exchanger.

The way out is to install an expensive water softening station or regularly descale with special reagents, which also costs money and is quite troublesome.

In the boiler, indirect heating of the accumulation of salts does not occur, the temperature of the coil does not rise above the level at which they are deposited.

The first minute or half a minute after turning on the mixer, cold water will flow in vain until the heat exchanger heats up. Systems with a storage boiler are more economical in terms of water consumption.

The boiler itself also does not provide instant hot water supply, but if there is a return circuit and forced circulation in the DHW system, it will always be warm.

Advantages of double-circuit boilers

Having two heat exchangers, a double-circuit boiler is capable of simultaneously heating the coolant and hot water, which is not possible with single-circuit ones.
In the maintenance of hot water supply, a double-circuit boiler is a little more economical in terms of gas consumption.
A double-circuit heat generator is more expensive than a single-circuit, but much cheaper than a set of a single-circuit and a large-capacity boiler integrated with it.
The wall-mounted double-circuit boiler has compact dimensions and, unlike the bulky set of boiler + storage water heater, takes up a minimum of space, can be installed both in the furnace and in the kitchen, in other non-residential premises, subject to certain conditions.

Although in terms of comfort, double-circuit boilers are significantly inferior to systems with an indirect heating boiler, their compactness and relative cheapness provide them with stable popularity. This is the most practical option for an apartment or small private house with local heating. True, a boiler with a built-in boiler is preferable, but it costs much more.

Gas double-circuit boilers

Unlike single-circuit gas boilers, equipped with a single heat exchanger, there are two of them in double-circuit ones. By design, additional heat exchangers for hot water supply can be divided into three types:

Separate additional primary heat exchanger. Primary - means that heating occurs directly by the flame. In fact, it is a smaller analogue of a heating heat exchanger. This design is most characterized by the disadvantages mentioned above. But this is the simplest and most inexpensive option, moreover, in the event of failure of one of the heat exchangers, each of them is repaired or replaced independently of the other.

The primary heat exchanger of a gas heat generator is very similar in design to a car radiator

The bithermal heat exchanger is a "tube in a tube" and is also the primary one. A coolant circulates in the outer part of the pipe, the inner one is intended for hot water supply. Such a scheme provides a more stable temperature regime, but it is more expensive to maintain and repair such boilers.

This shape of the bithermal pipe ensures its rigidity with uniform heating.

The secondary heat exchanger receives heat not from fuel combustion, but from the heat carrier heated in the primary heating heat exchanger.

Plate secondary DHW heat exchangers. A coolant circulates through two pipes, hot water circulates through a couple of others, heat is transferred by many thin steel plates

There is no need to strongly "clamp" the water flow in the secondary heat exchanger, therefore, with this design, the use of several mixers at the same time does not lead to a large temperature difference in the taps, the temperature drops are not so sharp. In addition, the secondary heat exchanger in some models can be integrated into DHW circulation. Alas, you have to pay for comfort and similar boilers are more expensive.

Scheme of operation of a double-circuit boiler in heating and hot water supply mode. Please note that the heating is temporarily switched off when heating hot water, as in a system with an indirect heating boiler.

Double-circuit boilers for other types of fuel

Liquid fuel double-circuit heating boilers, as a rule, have an autonomous primary heat exchanger for hot water supply, less often a secondary one. Accordingly, the system has the same pros and cons. There are also options with a built-in boiler.

The DHW coil heat exchanger of the liquid fuel heat generator operates independently from the heating

Solid fuel double-circuit heating boilers, despite a serious design difference with respect to gas and liquid fuel, heat hot water supply according to a similar principle, using a separate (primary) heat exchanger or built-in (secondary) coil, or in a small built-in storage boiler. The secondary heat exchanger and boiler can be connected to the hot water circulation system. Unfortunately, a solid fuel boiler is not able to fully provide a stable temperature due to the general unevenness of heat generation, with the exception of pellet boilers with automatic fuel loading.

In most solid fuel double-circuit boilers with a storage tank for hot water supply, the water in the tank is heated directly, by primary heat

Modern double-circuit electric heating boilers are equipped with a secondary heat exchanger and a DHW circulation pump, so the mode of their use is quite comfortable, although it does not reach the level of the boiler + indirect heating boiler system. Alas, heating with electricity is expensive.

To prepare hot water in double-circuit electric boilers, plate heat exchangers are also used.

How to connect the equipment correctly

The connection diagram for a double-circuit heating boiler is determined not by the type of fuel on which the heat generator operates, but by the type of heating system (with forced or natural circulation, single-circuit or double-circuit, etc.), and by the boiler equipment. For example, double-circuit gas and electric boilers for heating a house with a secondary heat exchanger are often already equipped with pumps, which allows them to be immediately connected to the circulation system of both heating and hot water supply. Liquid and solid fuel boilers, more often do not have pumps, they are installed separately if necessary.

A double-circuit boiler with a primary heat exchanger, in addition to the inputs of the supply and return heating lines, has two more connections: an inlet for cold water and an outlet for already heated one.

Connection diagram of a double-circuit gas boiler to a heating system and hot water supply without circulation. You should strive that the length of the hot water pipes from the heat generator to the mixer is as equal as possible, this will reduce the temperature difference when using several taps at the same time.

The piping of a double-circuit heating boiler, the scheme of which provides for the possibility of connecting to hot water supply with circulation, will be slightly different, a connection of the return line (circulation line) of hot water supply is added.

Diagram of connecting a solid fuel boiler to the hot water supply with a storage boiler and hot water circulation. Please note that check valves are installed on the hot and cold water supply

Connecting a heating boiler is a serious task. For all types of heat generators, this means design and installation of piping, integration of the boiler into the heating system. And for gas equipment there is also connection to the natural gas supply pipeline, which requires special approvals and licenses. Work in a boiler room is technically more difficult than laying heating communications in rooms; an error in calculations and installation can lead to improper operation of the system and even a serious accident. To be sure of the reliability and safety of home heating, responsible work should be entrusted to certified specialists.

Video: two-room heating boilers

Today gas heating is still the cheapest. Therefore, if there is a gas pipeline nearby and technical capabilities, it makes sense to install a double-circuit gas boiler. Why double-circuit? Because one device will provide both heat and hot water.

When choosing a double-circuit boiler, be sure to pay attention to several parameters:

installation method - floor wall;
power;
combustion chamber type (open, closed);
the type of heat exchanger and the material from which it is made;
set of service functions.

There are many other points, but these are the main ones. Without them, it is impossible to choose a double-circuit gas boiler, and we will talk about them further. And first of all, let's get acquainted with the structure of this equipment and the principle of its operation. Then all the stages of choosing a gas boiler for a house, apartment or summer cottage will be clear.

Structure and main differences

The gas boiler consists of three main modules - burner, heat exchanger, control automation. The burner is located in the combustion chamber, above it there is a heat exchanger, in which the coolant is heated. The whole process is controlled by automation. It provides safety and changes the operating modes of the equipment.

Heat exchanger types

A double-circuit boiler differs in that it can heat both water for heating and for water supply. This must be done separately, because special heat exchangers are needed. There are two types of them:

Double heat exchanger. Consists of two separate modules - primary and plate. In the primary, the coolant from the heating system is heated, in the secondary - plate - water for domestic needs. The primary heat exchanger is a finned tube, the secondary is a set of plates. They are located in different parts of the boiler - primary at the top, lamellar at the bottom, but they are interconnected because they are read as a single piece.
Bithermal heat exchanger. It consists of two metal tubes of different diameters, inserted one into the other. In the inner tube, hot water is heated, in the outer tube, for the heating system.

The system with a double heat exchanger is more reliable. Since the heating is a closed system and the coolant circulates in a circle, little scale is formed. When heating water for hot water supply, the situation is the opposite - running water heats up, which means there is a lot of scale. This part of the heat exchanger periodically requires repair or replacement. If in a double heat exchanger it is possible to replace only that part that heats water for domestic needs, then in bithermal separation is not provided, you have to change the entire device, and this is much more expensive. There is one more thing: a double-circuit gas boiler with a double heat exchanger normally works for heating, with a bithermic one the situation is different - it does not work at all.

Heat exchanger material

The choice of a double-circuit gas boiler can also be influenced by the material from which the heat exchanger is made. This could be:

It is not so difficult to choose a double-circuit gas boiler for this parameter. Copper seems to be the best option. Not without drawbacks - high chemical activity and low melting point - but they learned to compensate for them long ago. The boiler automation controls that there is no overheating. Chemical activity is neutralized by using chemically neutral materials in the heating system - using polymer pipes - polypropylene or cross-linked polyethylene.

Types of burners for gas boilers

In wall-mounted double-circuit gas boilers, atmospheric gas burners are installed. According to the method of controlling the flame, they are:

If we talk about the optimal choice, then these are modulating burners. They allow not only to maintain the heating temperature accurately, but also heat the water exactly to the specified parameters. If you want to choose an economical double-circuit gas boiler, it must have a modulating burner.

Automation

Automation in gas boilers is a must - it ensures safety, switches operating modes. There are three main parameters that are constantly monitored:

the presence of draft in the chimney;
gas pressure;
flame control.

These are key points that just need to be controlled. If at least one of these parameters is not normal, the boiler will not turn on. In addition, there is an extensive list of additional functions:

These are the functions that are common, but there are also specific ones: the ability to connect (and control) solar panels, floor heating systems. There is a weather-dependent automation. In this case, there are remote sensors that are installed outdoors. According to their data, the operation of the boiler is adjusted.

All these functions are embedded in the microprocessor, which controls everything. An ordinary user from all automation only comes across a remote thermostat, which can be installed in any room and according to the indications of which the temperature can be adjusted (another additional option). Basically, all interaction with the boiler and its automation is limited to a small socket. All necessary information is displayed on the screen. There are also buttons with which you change modes, set the temperature.

Principle of operation

A double-circuit gas boiler can operate in two modes - heating and water heating. In the boiler itself there are two circuits along which the coolant moves. One of them - with a primary heat exchanger - works for heating, the second - with a plate heat exchanger - for preparing hot water. The changeover takes place using a three-way valve.

The exact mode of operation of a double-circuit boiler is set by the manufacturer, but usually the mechanism of operation for heating is as follows:

With some variations, this algorithm of operation is repeated in different boilers. When heating water for domestic needs, everything happens in about the same way, only the signal to turn on the burner is the appearance of a water flow in the circuit. That is, you open the hot water tap, the burner ignites. Only in this operating mode, the three-way valve switches and closes the coolant inside the boiler. The secondary heat exchanger is heated from the hot coolant, and running water is heated from it. Heating stops when the water overheats (when the threshold is reached) or after the tap is closed. The burner goes out, the circulation pump runs until the heat exchanger cools down, then it turns off.

Installation method

According to the method of installation, gas boilers are floor-standing and wall-mounted. Wall-mounted - compact units, the size of a small kitchen cabinet. They do not require the equipment of a separate room, they can be installed in the kitchen or in another suitable room. The maximum power of a wall-mounted gas boiler is 30-35 kW. This is usually enough to heat rooms with a total area of 250-350 sq. m.

Floor standing gas boilers are more powerful, respectively, have larger dimensions and weight. There are models that can stand in a residential area, others require a dedicated room - a boiler room. The requirements for the installation are prescribed by each manufacturer separately, but usually the distance from the top of the boiler to the ceiling, the volume of the room and the presence of ventilation are stipulated.

Regardless of the type, a certified project is required for the installation of gas boilers. A gas meter is necessarily present in the circuit, so if it is not there, it will have to be purchased. Connection work must be carried out by a campaign licensed for this type of activity. Only in this case the boiler will be put into operation.

It is easy to choose a double-circuit gas boiler according to the installation method. If there is enough power, they usually take the wall version, if not, the floor version.

Combustion chamber type

The gas burner is located in the combustion chamber. There are two types of it - open (atmospheric) and closed (with a turbine, forced). A double-circuit gas boiler with an open combustion chamber can only be installed in rooms with good ventilation. During operation, the oxygen necessary for combustion is taken from the room, and the combustion products are discharged into the chimney with good draft. Therefore, you need a good air flow and a properly working exhaust ventilation duct.

Gas boilers with a closed combustion chamber are distinguished by the fact that at the outlet of the chamber there is a coaxial chimney (pipe in pipe) equipped with a fan. They bring the chimney out into the street, you can - into the wall near the boiler. Air is taken from the street through one pipe, combustion products are removed through the second, their movement is provided by a fan-turbine.

Which combustion chamber is the best? A boiler with a closed combustion chamber works more stably - air flows directly into the combustion zone. But there is also a minus in this: with a crosswind, the air flow can be so strong that it blows out the burner, the boiler turns off. The second disadvantage of this solution is freezing and ice formation in winter. Well, and the third drawback - such a boiler works only if there is electricity - it turns off without a turbine. Well, and another small minus - the turbine is not silent. It is almost inaudible, but it is “almost”. Apparently for these reasons, if there is a possibility (a serviceable ventilation duct), they put boilers with an open combustion chamber. After all, it is much easier to ensure a constant flow of air.

Boiler power

One of the key points in choosing a heating boiler is determining the required power. If we approach this with full responsibility, it is necessary to consider the heat loss of each room, if we are talking about an apartment or a building as a whole, if the boiler is selected for heating a private house. The calculations take into account the materials of the walls, their thickness, the area of windows and doors, the degree of their insulation, the presence / absence of an unheated room below / above, the type of roof and roofing material. It takes into account the geographical location and a whole bunch of factors.

Such a calculation can be ordered in a specialized organization (even in GorGaz or a design bureau), if you wish, you can master it yourself, or you can follow the path of least resistance - calculate it based on average rates.

Based on the results of all calculations, the norm was derived: for heating 10 square meters of area, 1 kW of heating power is required. This standard is suitable for rooms with 2.5 m ceilings, with walls with an average degree of thermal insulation. If your room falls into this category, divide the total area that needs to be heated by 10. You get the required boiler power. Then you can make adjustments - increase or decrease the resulting figure, depending on real conditions. It is necessary to increase the power of the heating boiler in the following cases:

The walls are made of a material with high thermal conductivity and are not insulated. Brick, concrete fall into this category for sure, the rest - according to the circumstances. If you are choosing a boiler for an apartment, you need to add power if the apartment is corner. For "internal" heat losses through them are not so terrible.
The windows are large and do not provide airtightness (old wooden frames).
If the ceilings in the room are higher than 2.7 m.
If in a private house the attic is not heated and poorly insulated.
If the apartment is on the first or last floor.

Reduce the design power if the walls, roof, floor are well insulated, energy-saving double-glazed windows are installed on the windows. The resulting figure will be the required boiler power. When looking for a suitable model, make sure that the maximum power of the unit is not less than your figure.

With or without boiler

It's about how the water is heated. A conventional double-circuit gas boiler acts as an instantaneous water heater. Hot water is often not needed all the time, but in small portions, which leads to frequent switching on / off of the boiler. This mode leads to rapid wear of the equipment, but it is not too expensive to turn off the water. The solution to this problem is a double-circuit gas boiler with a boiler.

A gas-fired boiler has a small built-in storage tank that stores a certain amount of heated water. When the hot water tap opens, the flow comes from the tank, when the stock comes to an end, the burner turns on and continues to heat the water. After the tap was closed, the boiler works for some time, filling the boiler, then turns off. This mode of operation leads to less wear and tear on the equipment. The disadvantage of gas boilers with built-in boilers is their large size, because you need to place the boiler somewhere else. There are models with a remote boiler, then the container is connected to the boiler, and the floor can be installed by the boiler or next to it.

Double-circuit gas boilers: manufacturers

Having decided on the technical characteristics, it remains to find a suitable model and choose a manufacturer. This is not easy at all - there are many firms on the market, prices differ decently. As usual, there are three segments - expensive, mid-priced and cheap.

Dear ones, these are products of European manufacturers:

Italian gas boilers - Ferroli (Ferroli), Beretta (Beretta), Ariston, Baxi (Baksi).
German ones are not inferior to them in quality: Viessmann (Weismann), Wolf (Wolf), Vaillant (Vialant).
Korean Navien (Navien) are a worthy competitor to the leaders.

This equipment works reliably and without interruptions, but only under certain conditions. The first is a stable power supply, without significant fluctuations in frequency and voltage. Our networks do not sin with stability, therefore a voltage stabilizer is needed, and better - an electronic one. The second condition for normal operation is a certain gas pressure in the line. Most of the German and Italian gas boilers work if the gas pressure is 2 atm or more. An exception is the boilers Ariston and Navien.

Wall-mounted double-circuit gas boilers of Russian production - Danko, Protherm (Proterm) - have proven themselves quite well in the market. They have approximately the same functionality as the "Europeans", but they are less sensitive to deviations in the power supply, they work at low gas pressure. What is not encouraging is the Russian "service".

There are also Bosch boilers (Bosch). The company itself is German, but there are factories in Russia, so it is not easy to determine the geographical origin of these boilers - some are produced in Russia, some at other factories in other countries. The Bosh campaign specialists have developed a new boiler model adapted to our conditions - Gaz 6000 W.