What is a double-circuit gas boiler? How to choose double-circuit gas boilers among the variety of models? What is a double-circuit heating boiler

It is impossible to imagine a house or apartment without heating. Man has invented many devices for heating homes, but gas double-circuit boilers heating systems with unique consumer properties, are extremely common and occupy up to 75% of the market heating equipment. The market offers imported and domestic production, selection of products from different manufacturers huge. How to choose the most efficient, safe and durable home heating unit? For example, if you choose a double-circuit gas boiler, what is it and why is it better than other appliances?

For comfort in the house, heating alone is not enough, because you also need hot water for household needs, and its supply can be provided by a double-circuit gas boiler for heating, which needs to be selected correctly. This device is quite complex, expensive and can be purchased at long years, therefore, gross mistakes when choosing a boiler are unacceptable. The question of how to choose double-circuit gas boilers, which are the best and most reliable, is difficult to answer unequivocally, because many different factors should be taken into account when purchasing.

The modern one is a high-tech product that heats the home and supplies hot water for the hot water circuit. To minimize human intervention in the operation of the heating system, the units are equipped with complex automatic systems.

The power of boilers offered on the market varies, from tens to hundreds of kilowatts, which makes it possible to select a heating unit for a house of any size and number of floors. The price for gas boilers depends on the manufacturer’s brand, power and model of the boiler. The design of most models fits perfectly into the interior of the premises.

Double-circuit boilers at the installation site are divided into two large groups:

  1. floor-mounted double-circuit units with high power and weight;
  2. wall-mounted double-circuit gas appliances.

Floor-standing double-circuit boilers

For private houses with a large area and several floors, in specialized stores or online stores you can select and buy a double-circuit floor-standing gas boiler with the estimated power required to heat a particular home. These units have significant weight and size, so their installation requires separate room– boiler room.

Models are available that are network-dependent and non-volatile. This criterion should be taken into account first of all before buying a heating gas boiler, because the electrical network may be unreliable or completely absent. It should be taken into account that closed systems heating systems of complex configuration do not work without, so for uninterrupted operation need to install source uninterruptible power supply(UPS) or gasoline generator. For simple open systems, in which the coolant moves due to gravity, depending on electrical network absent.

Types of floor-standing gas boilers:


Wall-mounted gas double-circuit boilers

Not so long ago Russian consumer got the opportunity to purchase a double-circuit wall-mounted heating boiler. Products of this type have earned consumer recognition for short term became popular for autonomous heating. extremely compact, they can fit into any interior or be built into a closet, making it invisible. The power of mounted boilers, depending on the model, ranges from 13 to 55 kW.

Wall-mounted models of gas boilers, despite their small size, contain the following components and devices:

When choosing a wall-mounted double-circuit boiler, you need to try to take into account many characteristics for the optimal choice of unit model that will provide heating for the house and hot water.

You should not choose a double-circuit wall-mounted gas heating boiler with a power significantly exceeding the calculated value.

Typically, 20% is added to the design power, and for areas with extremely low temperatures in winter time up to 50%.

The main advantages of double-circuit wall-mounted boilers:

Leaders in the heating equipment market

To understand the development trends and demand for heating equipment, leading company specialists make analytical reviews in which they present a rating of gas double-circuit boilers, those that had the greatest demand and popularity. Reviews explain in detail why on the list the best products included the most popular models of heating equipment.

IN Lately there is a stable trend - the demand and sale of double-circuit gas boilers has increased significantly, especially the new generation boilers. Many companies offer completely new innovative solutions that will create even more advanced products.

The most popular gas boilers in Russia

The popular Ross gas boiler is produced at the Kharkov plant in the form of wall-mounted, floor-standing and parapet models. They differ in power and quantity additional functions. The popularity of Ross boilers is due to affordable price And high quality units. You can order a boiler at the factory without intermediaries, which will significantly reduce costs.

Wall-mounted double-circuit gas boiler Avangard with a rated power of 24 kW. The boiler meets European standards in its technical characteristics and has all the necessary certificates. The device is non-volatile with a cast iron heat exchanger and comes with a 10-year manufacturer’s warranty. The unit is equipped with Italian non-volatile automation. All components from leading European companies.

The Vulcan wall-mounted gas boiler is one of the ten best-selling units in Europe. Models with power from 7 to 20 kW are available. All models of Vulcan boilers are equipped with imported automatic equipment, they are relatively inexpensive and are designed for heating small houses and apartments.

The popular gas boiler Termotechnik is a standard heating device simple design. Its technical data is lower than that of advanced foreign models. But the fact that its price is several times lower than that of imported products, it works stably and reliably in operation, and determined its extraordinary popularity in Russia.

From all of the above, we can assume that the popularity of wall-mounted double-circuit boilers will increase.

Many manufacturers are working to improve the performance, efficiency, safety and reliability of their products.

Many companies that produce heating equipment have the main part of their product range in wall-mounted double-circuit boilers designed for organizing hot water supply systems and heating homes. It seems that this trend will continue in the foreseeable future.

Can one device both heat a house and provide hot water in the tap? Yes, if this device is a double-circuit boiler with a built-in boiler (otherwise “built-in DHW boiler”).

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On the picture:

Diagram of a “double-circuit” boiler: one part is responsible for heating water in the heating system, the other for hot water from the tap.

The concept of “double-circuit boiler” implies that the unit works for the needs of two systems at once: hot water supply (DHW) and heating. Moreover, many models are designed according to the principle of hot water priority. That is, when water begins to be consumed (the water tap is opened), the boiler power is redistributed in favor of the DHW circuit. The coolant in the heating system does not heat up.

However, there is nothing wrong with such a scheme of work: even with active use of water for some time, the temperature in the house will drop by no more than 1-3 degrees.

Double-circuit boilers are wall-mounted and floor-mounted.

Wall-mounted double-circuit boiler characterized by relatively low power and performance. Its advantages are compactness and light weight. Wall-mounted double-circuit boilers are well suited for small houses with 2-3 water points.

The hot water preparation system in these devices is similar to instantaneous water heaters: they also use plate heat exchanger, heated by the operation of a gas or diesel burner. There are storage models of double-circuit boilers: a small container of several tens of liters is installed inside the boiler. However, the tank volume of the built-in boiler is small. Such a unit, unlike a flow-through unit, is unable to fully meet the needs big family in hot water. A double-circuit storage boiler can only be installed in a country house.


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On the picture:

A wall-mounted double-circuit boiler will be located in small room and will not spoil the interior with its appearance.

Floor-standing double-circuit boiler has a much more spacious storage tank for the DHW system. However, its capacity rarely exceeds 100-150 liters (otherwise the device body would be unreasonably large).

Hot water is prepared in the same way as in water heaters indirect heating. A floor-standing double-circuit boiler allows you to meet the needs of a family of 4-6 people, despite the fact that the house is equipped with 2-3 bathrooms. If there are more water points, the water supply from the built-in boiler will be insufficient. In this case, you will have to use additional water heaters or completely abandon the double-circuit boiler, giving preference to an independent DHW scheme based on a free-standing water heater.


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On the picture:

A floor-standing double-circuit boiler will have to be moved to a separate utility room, but at the same time it will provide water and heat to the whole house.

What is better: to have an independent hot water supply and heating system or to buy a double-circuit boiler?

Advantages of a double-circuit boiler:

  • Space saving.
  • Lower costs for equipment installation and maintenance. Maintenance of only one device (even a combined one) is much cheaper.
  • Two on one DHW systems and heating will operate on the same fuel line, chimney. They only need one complex of automatic control and security.
  • All inclusive. In most cases, such units are supplied complete with all the necessary additional devices (piping) - circulation, expansion tanks etc.
  • Doesn’t “drown” in summer . It is very easy to switch a double-circuit boiler from the “heating and DHW” mode to the “DHW only” mode.

Disadvantages of a double-circuit boiler:

  • Low hot water productivity in a double-circuit boiler of any type.
  • Forces you to save water. Due to the strict limitation of its volume, hot water has to be used very sparingly.
  • Hot water / heating = not proportional. If you increase the tank capacity, you will need a more powerful (more expensive) boiler. And these are completely unjustified costs. Indeed, to heat a house, sometimes even a quarter of the rated power of the device is enough.

The article uses images from sankon.com.ua, sogreemdom.com,

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Double-circuit boilers

Korean heating boilers

Don't depend on quality central heating and hot water supply is quite simple. All you have to do is install the boiler at home and independently regulate the temperature and duration heating season. And if in apartment buildings installation of autonomous heating for safety reasons may be prohibited, depending on the number of storeys, then in one-story cottages and private houses, this The best decision heating and hot water problems.

The main thing in an autonomous heating system is, of course, the boiler. There are several types of them. For fuel they use both traditional fuel - gas and coal, so alternative fuel- wood chips and briquettes. Single- and double-circuit boilers are most preferable for installation in a cottage.

Single-circuit heating boilers

A single-circuit boiler primarily works to heat rooms and create comfortable temperature. As the name suggests, one coolant circuit passes through the boiler. If desired, a heat exchanger can be connected to the heat source to heat the water. Principle of operation single-circuit boiler extremely simple. Fuel enters the firebox, which heats the coolant circulating through the pipelines inside the boiler. Coolant circulation through heating circuit occurs either due to temperature differences or using a circulation pump. For high-quality heating of premises, water circulation in the circuit must be constant.

single-circuit boiler with a connected boiler, hot water comes from the boiler


As for connecting an additional heating circuit, which is located outside the boiler, it will not be difficult to connect it. But is there any benefit to this? The thing is that connecting a boiler to heat water will make the operation of the boiler unstable. This is due to the fact that the amount of heat required to heat water is not constant throughout the day. Maximum water withdrawal occurs in the morning and evening hours. The boiler needs to be rebuilt and more fuel supplied to the burner. After cessation of consumption, the boiler remains to work only for the heating system. Such operation of a single-circuit boiler will not be economical and will lead to excessive fuel consumption.

Advantages of a single-circuit boiler:

  • Such boilers are equipped automatic system security. It is this that allows you to select the optimal operating mode of the equipment and fuel consumption.
  • On the basis of single-circuit boilers, you can create a variety of heating systems with different wiring in rooms. Right choice allows you to increase the service life of the boiler, as well as improve it specifications.
  • New models of single-circuit boilers have built-in weather control sensors. This means that the outside air temperature regulates the fuel supply to the burner, and consequently reduces or increases the temperature in the supply pipe.
  • The simplicity of the design makes single-circuit boiler models very reliable and easy to control and regulate.

Double-circuit boilers

If living without hot water is not part of your plans, then you should think about purchasing a double-circuit boiler. It differs from a single-circuit one in that its design includes an additional heat exchanger for heating water. Depending on the power of the boiler, it is possible to organize heating of water and supplying it to two water points at the same time. To minimize the cooling of water on the way to the points of analysis, it is advisable to place the boiler closer to them.

There are two types of double-circuit boilers: with one or two heat exchangers. In the first case, coolant passes through the heat exchanger for heating needs. If it is necessary to heat cold water, the supply of coolant to the heat exchanger is shut off, and the supply of cold water for heating is opened. This is not very convenient, especially in the cold season.

Boilers with two heat exchangers are more popular. They work independently of each other. In one heat exchanger, heating water is heated, and in the other, cold water is heated for the needs of hot water supply. Modern double-circuit boilers are equipped with steel heaters that heat water in a short period of time.

double-circuit boiler, hot water comes from the boiler


Advantages of a double-circuit boiler:
  • Purchasing such a boiler will cost less than a set consisting of a single-circuit boiler and a boiler.
  • The boiler is quite compact.
  • Water is not collected into the storage tank, but exactly the amount of water that is needed is heated. this moment. This reduces heat loss due to cooling.

How to choose a boiler of appropriate power

If the choice in favor of a single- or double-circuit boiler has already been made, then it is necessary to select a boiler of appropriate performance. In order to ensure that the air temperature in the rooms is comfortable and the hot water temperature is about 50 degrees Celsius, you can make a simple calculation of the power of the installed boiler. To do this, the area of ​​all heated rooms is summed up and divided by 10. This gives an approximate heating load. By increasing it by about 15-20%, we have the total power of the boiler, taking into account the hot water supply. However, as professionals advise, it is worth purchasing a boiler with a slightly higher productivity than that obtained by calculation. The thing is that over time, the performance of the equipment decreases, the heat transfer from the fuel to the coolant decreases, due to contamination of the heating surfaces. In addition, when selecting equipment, one should take into account the amount of heat loss from pipelines and possible voltage drops.

Boiler manufacturers - which model is better?

It’s easy to get confused in the variety of brands offering their products. How to choose a boiler and not make a mistake with the choice. Currently, the heat and power products market mainly offers equipment from several countries. These are Germany, Italy, Korea and Russia. All boilers have some differences associated with the technical characteristics of their work and also significant differences in cost.
German heating boilers.


Bosh boilers have proven themselves for a long time with the best side. Their design is constantly being improved. The boiler is equipped with automation and safety devices that regulate the fuel supply to the burner and are activated in the event of an emergency. To improve heat removal during boiler operation, all heat exchangers are made of copper, which are coated with a special composition to prevent corrosion. The estimated service life of such a boiler is 20 years.

Another German company producing boilers high class, This Viessmann company. They specialize in the production of both single- and double-circuit boilers. Their equipment is characterized by excellent assembly and technical characteristics. According to the stated characteristics, the efficiency of such boilers reaches 93%. In addition, the company's engineers have developed a unique chimney design that prevents condensation of flue gases in the pipe and, as a result, their freezing.

Italian heating boilers

Boilers from Italian companies also differ good quality assemblies. One of the most famous Italian brands– Beretta, produces high-power boilers. In the model range you can select heating equipment with a power of up to 24 kW. These can be single-circuit, double-circuit boilers, boilers with a built-in or free-standing boiler. A distinctive feature of Beretta equipment is that it can operate even in very low temperatures outside air.

Baxi has been on the heating equipment market for several years. During this time, specialists are constantly developing and implementing new solutions. Fifth generation boilers have a burner atmospheric type, which operates almost silently. Baxi equipment is represented by a wide range model range power from 10 to 80 kW. The boilers have relatively small sizes and a high coefficient useful action– up to 90%.

Korean heating boilers

Korean-made boilers combine modern technologies and reliability. They are equipped with protection systems against voltage surges, increased pressure and temperature in the collectors. The boiler also has a built-in natural gas leak detector. If it is detected, the boiler automation will shut off the gas supply to the burner device.

Navien is a leading manufacturer of boilers. It produces boilers operating on various types of fuel with varying amounts contours. The equipment is equipped with burner devices that operate even at low natural gas pressure. In addition, a voltage stabilizer is built into the boiler, which protects the system from overloads.

The Olympia company specializes in the production of double-circuit boilers equipped with a weather control system. The power range of models of this brand is quite wide, which allows you to choose a boiler for a room of any size. All boiler models are equipped the latest system automation systems that allow you to smoothly regulate the operation of equipment and even protect the system from freezing.
Domestic boilers.

Danko boiler equipment regularly receives good feedback from users and experts. From the model range presented by the company in the range from 7 to 15 kW, you can easily select a boiler for heating a small country house or apartments, subject to permission. The boiler unit is equipped with a gas filter, a steel heat exchanger and an economical micro-torch burner.

Another company that produces competitive boiler equipment is OJSC Borinskoye ISHMA BSK. Distinctive feature The advantage of these boilers is that they are produced with a built-in circulation pump. In this case, the boiler can operate both with and without a working pump. This is very convenient when there are frequent power outages.

What to look for when buying a boiler

  1. Burner. The economical operation of the boiler depends on it. It is important that the burner design facilitates high-quality mixing of gas and air, and therefore complete combustion of the fuel without chemical underburning. The most economical are automatic burners with a built-in fan. Before being fed into the furnace, the gas is mixed with air and then fed into the boiler. The disadvantage of such a burner is the additional noise created by the fan.
  2. Heat exchanger. The quality of heat transfer from combustion products to the environment depends on the material of the heat exchanger. Optimal choice there will be a heat exchanger made of steel or copper. They are distinguished by high thermal conductivity and resistance to aggressive environmental influences. In addition, it should be taken into account that under the influence of high temperatures and corrosion, its elements often fail. The more famous the boiler brand, the easier it will be to select a replacement part.
  3. Electronics and automation. The boiler, equipped with sensors and allowing operation to be adjusted by just pressing a few buttons, is simple and easy to use. But it is worth considering that if there is a power outage, the boiler protection will work and the fuel supply to it will stop. You should choose equipment that has the ability to manually regulate its operation in any case.
According to customer reviews, boilers of German and domestic production are considered the best. They are easy to maintain. Repair is also not difficult, since there are many service centers who order components and repair parts directly from the manufacturer. Boilers of Italian brands, on the contrary, have caused complaints from consumers due to a short warranty period, difficulties in repair and selection of spare parts.
It is important to be careful when choosing a boiler. After all, it will last for decades and will create a feeling of comfort and coziness on winter evenings.

Today, the most popular gas boiler can not only heat a house, but also prepare hot water in running mode. have tightly 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 abandoned soon.

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

When it comes to preparing hot water, a gas double-circuit boiler is in no way inferior geysers in terms of comfort, speed and volume of hot water preparation. The hot water production capacity of double-circuit boilers averages 8-12 liters per minute.

Hot water can be prepared in a double-circuit boiler various options:

  • through a secondary plate heat exchanger;
  • through a bithermic 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 intended for?

A heat exchanger is a device in which heat is exchanged between two coolants having different temperatures. Heat exchanger gas boiler designed to transfer heat released during fuel combustion. The heat exchanger is located above the gas burner and when the gas burns, 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 into two types according to the types of heat exchangers:

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

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

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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. Inner pipe The heat exchanger is intended for the preparation of hot water supply, and the external one is for heating the coolant of the heating system.

What are double-circuit gas boilers? 200 111 What are double-circuit gas boilers? What are double-circuit gas boilers?

Let's consider options for double-circuit gas boilers with various types heat exchangers during their operation for heating the system and preparing hot water supply.

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

Schematic diagram The design and operation of such a boiler is presented in [Fig. 4].

Essential elements:

While the boiler is operating in heating mode, the gas burner (1) transfers heat to the primary heat exchanger (5). Coolant circulation is ensured by a pump (2). The three-way valve (3) prevents liquid from entering the secondary heat exchanger. The hot heating fluid 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 design and operation of such a boiler is presented in [Fig. 5].

When the boiler is operating to prepare hot water, the three-way valve (3) closes the heating line (A). The hot coolant 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, warms up and enters the hot water supply line (B).

3. Double-circuit boiler with a bithermal heat exchanger when operating on a heating circuit.

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

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Essential elements:

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

While the boiler is operating in heating mode, the gas burner (1) transfers heat to the bithermal heat exchanger (2). Coolant circulation is ensured by a pump (3). The hot heating fluid 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 bithermal heat exchanger when operating on a hot water supply circuit.

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

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

Based on the principles of operation of double-circuit gas boilers described above, we can conclude 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 our conditions. winter period.

Also, replacing a secondary heat exchanger costs significantly less than replacing the entire bithermal heat exchanger.

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

The advantage of boilers with a bithermic heat exchanger is their relatively inexpensive price compared to gas boilers with two heat exchangers, as well as a larger capacity for preparing hot water due to large area heat exchanger (compared to plate heat exchanger).


Product selection

From the question asked, it is clear that the dacha is supposed to be heated. That is, the facility is located outside the city, far from hot water mains. Hot water is always needed for various household needs, so the speed and availability of its heating is not the least important for everyone. A special feature of a double-circuit gas boiler is that it has two functions: heating the room and heating water for water supply. It performs both of these tasks independently of each other.

Design and principle of operation of a wall-mounted gas boiler with two circuits

Almost all boilers operating on natural gas, have a similar device. Each of them has a burner, heat exchanger and electronic automation. The burner is located in a combustion chamber, which can be either open or closed. The second is more practical and safe. The burner creates a flame of intensity specified electronically. This flame heats the heat exchanger in which the water circulates. The automation supports user-programmed combustion parameters and performs an emergency shutdown of the unit in the event of technical problems, including overheating, a decrease or increase in pressure in the system.

A double-circuit boiler differs from a single-circuit boiler only in the design of the heat exchanger. In the second, it looks like a single tube with ribs, inside which water flows from the heating system and is heated by the flame. In a double-circuit boiler, the heat exchanger is double, which allows you to use energy not only for heating, but also for heating water in the water supply. The heating circuit runs continuously unless it is turned off, which happens in the summer. The water circuit is activated when the hot water tap on the sink or shower is opened.

It should be borne in mind that double-circuit boilers have a flow-through water supply system, so you will only have to wait a few seconds until it is completely heated.

Advantages of a double-circuit wall-mounted boiler

Double-circuit boilers have a number of advantages:

  1. Use of gas for both heating and water heating. It is much cheaper than electricity. For a private home or cottage, you can’t imagine anything better.
  2. Simple installation, which a specialist will carry out very quickly. You can even install it yourself if you wish.
  3. Minimum inconvenience in operation. Anyone can master the clear controls. It's easier than the TV remote control.
  4. Excellent efficiency. At small sizes and low gas consumption, the boiler is able to heat large rooms.
  5. There is a market great amount boilers with different capacities, which allows you to choose the optimal one.

In conclusion, we can add that a double-circuit boiler is capable of automatically switching between heating and water supply modes. This is what a double-circuit gas boiler is. Whether or not to choose such a boiler is the user’s decision.