Boiler single or dual circuit. Which is better to choose a gas boiler - single or dual circuit?

The question of how the hot water supply will be organized in the house should be solved as soon as possible - even at the stage of choosing a gas boiler. The optimal solution takes into account all the features of the house.

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On the picture:

What is the difference?

In hot water supply (HWS).Single-boiler, if used without additional equipment, heats the water only for heating. Dual circuit - both for heating and for hot water supply for domestic needs.

Double boiler.   Its design provides for special devices for organizing hot water supply: an additional heat exchanger, in which a hot coolant heats the water from the cold water supply system (CWS), and a valve that controls the movement of the coolant. In one position, the valve directs the heated coolant to the central heating system (DH). But as soon as the hot water valve opens (someone begins to use it), the valve changes position: the coolant moves to the heat exchanger and heats the water for the DHW system. In all such devices, the priority of hot water is incorporated: while the hot water valve is open, the central heating system is disconnected from the boiler.

Single circuit boiler.Modern single-circuit boilers can also heat water for domestic needs, but this requires a boiler, which is purchased separately. This is a tank with a spiral heat exchanger inside; it passes the coolant from the boiler and heats the water for hot water supply. There is also a valve that controls the flow of coolant from the boiler, also based on the priority of the DHW. Almost all modern single-circuit boilers are equipped with devices for operating the boiler. If the boiler is purchased without these elements, then an expert must select and install them.

a) 1 - single-circuit boiler, 2 - central heating system, 3 - connection to the DHW system, 4 - indirect heating boiler, 5 - cold water; b) 1- double-circuit boiler, 2- DH system, 3- connection to the DHW system, 4- cold water

Dimensions and power

Double-circuit gas floor boilers. They require special attention to the choice of power - the “power” of the jet from the hot water tap depends on it. To prepare a hot bath, the minimum boiler power should be 18 kW, for a shower - not less than 10 kW. However, so that at the moment of opening the second hot water tap your shower doesn’t turn into a contrast one, choose a gas double-circuit heating boiler with a minimum power of 28 kW.

Single-circuit boilers.   In them the determining value is the volume of the boiler. The more tenants in the house and the more often they like to bask in the bathroom, the more volume is needed. The standard volume of the boiler complete with the boiler is 100-120 liters, however, a large bathroom with hydromassage will not be pulled by the boiler of 300 liters.

1) boiler body, 2) polyurethane foam insulation, 3) a pump that circulates coolant through a boiler heat exchanger, 4) a heat exchanger, 5) cold water supply nozzle, 6) expansion tank, 7) non-return valve, 8) hot water supply system, 9) circulation pipe, 10) circulation pump, 11) thermostat, 12) safety valve, 13) emergency drain

Completeness

In dual circuit - everything is there.As a rule, the double-circuit floor gas boiler for heating is already equipped with everything necessary: ​​a circulation pump, a safety valve, a diaphragm expansion tank and fittings. All that is needed to install such a mini-boiler room is to bring gas, pipes with water and a pipe for diverting combustion products.

In single - all separately.Not only do you need to buy additional equipment, you also need to install it in the boiler room, which requires a lot of space. In this sense, wall-mounted single-circuit boilers are more convenient - they already have a part of the required units, all that remains is to connect a water heating boiler for the DHW system with protection elements.

Single circuit.You need a place - both for the boiler itself, and for the expansion tank, pump, safety valve. Considering not only the size of the system, but also its unaesthetic appearance, it is better to place it away from the eyes. At the same time, the installation of both of these and other boilers is not difficult for a good specialist.

Which is more compact?

Dual circuit.If the house has a minimum of free space, then a double boiler will be the best choice. Because of the uselessness of the boiler and due to the valves already mounted in the housing, it is easier for it to find a place.

Which is better?

Dual circuit more economical. The double-circuit boiler is turned on only when the need for water arises. Single-circuit is always turned on when the water is cooled (in the boiler this happens after a couple of hours). And even if it is not used, it spends fuel on heating.

Single circuit is more convenient.Hot water flows from the tap immediately and evenly. It does not get colder if someone opens somewhere another tap. The boiler heats the entire volume of water at once, so you can use it without any special restrictions.

The following images were used in the article: viessmann.com

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The only task that can be solved by a single-circuit gas boiler is to heat the coolant in the heating system. Dual-circuit devices, in addition to this function, also heat water for technical, sanitary needs (for example, washing dishes). The principle of operation of the single-circuit device is simple: water is heated in the heat exchanger by means of gas and enters the heating system of the house. Dual boiler is more complicated.

In this type of apparatus there is a pair of circuits, plus a heat exchanger, with one of the circuits connected to the heating system, and the second to the hot water supply system (or HWS). When the heating system is operating, hot water is not supplied to the circuit connected to the DHW; This is prevented by a special valve. As soon as the tap or other consumer connected to the DHW opens, the automatic system is activated (due to the pressure drop) and the valve cuts off the hot water supply to the heating system of the house — the entire flow is sent to the DHW. As soon as hot water is no longer used, the opposite happens, it starts to flow again for heating needs.

Specific use of double-boiler

Dual-circuit devices are preferable in terms of comfort, because at the same time they heat the house and provide it with hot water for on-farm needs. However, there are situations when it is not economically feasible to use more complex in design and expensive “double-circuits”. For example, if the house already has a centralized DHW (this may be a thermal source). Another situation is a high, constant need for hot water. It is worth remembering that when the DHW consumers are working, the coolant in the heating system of the room will cool down without providing the required temperature. In these two cases, the advantage of single-boiler is obvious. However, such situations are rare and that is why “double-circuits” are popular among most homeowners as the most effective means of heating and supplying hot water.

In the Russian conditions, when the water pressure is not constant, double-boiler with a boiler is of particular attractiveness. Such devices do not depend on water pressure; in case of its decrease, the heating system will function with the same efficiency. The only minus of a double-circuit boiler with a boiler is a higher cost.

Gas boilers are common due to the low cost of gas and great ease of use. These factors are the reasons why people continue to equip their heating systems with such boiler equipment. But before installing such boilers, many home owners have to choose between a single-circuit and double-circuit boiler.

Design features

The structure of the single-circuit boiler is very simple. It is represented by:

1. Gas burner.
2. Automatics that controls the burner.
3. Special gas ignition device.
4. A pipe that is placed above the burner, and through which the coolant flows.

Thanks to this design, a single-circuit gas boiler can heat water only for the heating system. It can also be used for hot water supply, but this requires buying, which is often noted in various videos. They also tell about the difference between gas devices and which one is better to choose.

As for the structure, the difference between it and the design of the above-described unit is available:

1. Three way valve.
2. Small heat exchanger.
3. Expansion tank.
4. Security groups
5. Pump

The rest is the same. Of major importance among these additional nodes are the first two elements. The rest are necessary for the safe operation of the device and the entire heating system.

The three-way valve is able to change the direction of movement of the heated coolant. By default, it allows heated water in the heating system. If one of the residents of the house opens the hot water faucet, the duct sensor is activated, and at his command the valve closes the hole that supplies water to the heating system of the private house and opens the hole through which the heat carrier enters the heat exchanger with small dimensions.

It is a container with a spiral pipe. Inside the tank is running water, and the hot heat carrier moves in a spiral, which also heats the flow-through substance for hot water supply. The coolant will be sent to the heat exchanger as long as the hot water valve remains open. The heating system at home at this time remains without a source of heat. It is clear that it cools.

As can be seen from the above, the design of a double-circuit gas boiler allows you to heat the house and have hot water in the kitchen. This is one of the reasons why people want to choose it.

Pluses single-boiler

Its main advantage is that the price of one unit without much less than the cost of the second type. This is due to the simplicity of the structure. However, this plus turns into considerable difficulties, because you need to buy additional elements for binding and look for a specialist who can connect them.

If we consider the advantages of the boiler only in terms of the heating system, then it no longer has any advantages. However, they appear when an indirect heating boiler is connected to it. Of course, the additional node becomes part of the strapping. However, it is turned on so that, if necessary, the coolant can move around it. The positive aspects of a single boiler boiler are:

1. Independence of work from pressure in a water supply system.
2. Continuous supply of warm water. The good news is that the boiler allows you to create a circulation of heated water. This means that after opening the tap, hot liquid flows immediately.
3. You can use hot water without restriction (especially when taps are opened in the kitchen, bathroom and other rooms at the same time).

Cons of units with a single circuit

The downsides are:

1. To connect the heating system at home, you need to purchase a security group, a surge tank and a pump. On the difficulties associated with their installation, do not need to talk.
2. The large size of the floor boiler models, as well as the need for space for the above-mentioned additional elements. This means that in the kitchen to place it will not work. Required is additional space.
3. The complexity of installation. It is enhanced by the fact that it is necessary to additionally connect the indirect heating boiler and make a more complex system of DHW pipelines. Additional pipes are needed for constant circulation of warm water through the HWS. It cannot circulate by itself. That is, you need a pump.
4. The cost of the boiler along with the boiler is higher than the price of a double-circuit boiler.
5. Since the water in the hot water gradually cools down, it must be heated from time to time. Additional heat requires more gas. The bad thing is that this heating occurs at a time when hot water is not needed.

Of course, these disadvantages can be minimized. According to various videos to avoid difficulties with the lack of space and complexity of installation, you can purchase a kit with wall-mounted versions of the boiler apparatus and an indirect boiler. In the first element is built all the necessary equipment. Both units are small in size and can therefore be installed in the kitchen. Here you need to understand that you have to limit yourself in the volume of the boiler, which is why hot water will not always be.

As for the heating of water in the heat supply of hot water, you can use a three-way valve and automatic, which controls the operation of the valve. Automation allows you to set the operating modes of the valve, which will shut off the flow of coolant to the boiler at an unnecessary time (at night or when everyone has fled to workplaces).

Pluses of gas boilers with two circuits

They are:

1. Device is   cheaper, than a single-circuit boiler with a boiler. If the price of the boiler is not included in the price of the alternative, then it is more expensive.
2. Compactness. It has a small size, and therefore it can be mounted without problems in the kitchen.
3. The presence of all necessary additional equipment.
4. Ease of installation. Almost all models are wall. To connect, connect the pipes of the heating system of the house and the DHW. It is also necessary to attach a gas pipe, but this should be done by the specialists of the company supplying gas.
5. Heats the amount of water that is in demand. Thereby more economical.

Cons of dual circuit devices

A gas boiler with two circuits can disappoint people who want to choose it with such disadvantages:

1. Water in the DHW has a non-constant temperature. This is due to the fact that when you open the tap water only begins to heat up. Since it is flowing, cool fluid first flows, then warmer. Also, the variability of temperature affects the pressure in the water supply. The smaller it is, the colder the liquid is. With a strong drop in pressure in the plumbing hot water can not wait.
2. Temperature drops when several taps open. For this reason, the unit with two circuits is not suitable for homes with a large number of consumption points. For such a building, it is better to choose a 1-loop unit with a boiler.
3. The farther from the boiler is the point of consumption, the longer need to wait for warm water. This is due to the fact that there is no circulation in the DHW system, and the liquid is constantly cooled. The longer the family does not use DHW, the colder the water in the pipe between the boiler and the tap becomes. From this minus another one arises - cold water that flows previously warm, just pours into the sewer, because the residents of the house are waiting for a warm liquid.
4. The inclusion of the second circuit occurs only when the water flow is very noticeable. Because of this, you can forget about saving.

It is worth saying that not all have such disadvantages. Thus, a device with a storage tank (the volume varies in the range of 15-60 liters) or a layer-by-layer heating boiler is able to supply liquid with a constant temperature regardless of what the pressure in the water supply system is.

Double boiler

Korean heating boilers

Do not depend on the quality of central heating and hot water is quite simple. It is only necessary to install the boiler at home and independently regulate the temperature and duration of the heating season. And if in multi-apartment buildings, installation of autonomous heating for security purposes may be prohibited, depending on the number of floors, in single-story cottages and private houses, this is the best solution to the problem of heating and hot water.

The main thing in the autonomous heating system is of course the boiler. There are several types of them. They use both traditional fuel - gas and coal, as well as alternative fuel - chips and briquettes as fuel. The most preferred for installation in the cottage single and double boilers.

Single-circuit heating boilers

Single-boiler primarily works on space heating and creating a comfortable temperature in them. As the name implies, one coolant circuit passes through the boiler. If desired, a heat exchanger can be attached to the heat source to heat the water. The principle of operation of the single-circuit boiler is extremely simple. The furnace receives fuel that heats the coolant circulating through pipelines inside the boiler. Circulation of the coolant in the heating circuit occurs either by the temperature difference or by means of a circulation pump. For high-quality space heating water circulation in the circuit must be constant.

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

As for the connection of 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 fact is that connecting the boiler to heat the water will make the boiler unstable. This is due to the fact that the amount of heat needed to heat the water is not constant during the day. Maximum water intake occurs in the morning and evening. The boiler needs to be rebuilt and more fuel is supplied to the burner. After the consumption is stopped, the boiler can only work on the heating system. Such work 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 with an automatic security system. It allows you to choose the optimal mode of operation of the equipment and fuel consumption.
• On the basis of single-circuit boilers, you can create a variety of heating systems with different wiring around the rooms. The right choice allows you to increase the life of the boiler, as well as improve its technical characteristics.
• In the new models of single-circuit boilers built-in weather control sensors. This means that the control of the supply of fuel to the burner, and consequently a decrease or increase in temperature in the supply line, occurs from the outside air temperature.
• The simplicity of the design makes single-boiler models very reliable and easy to control and regulate.

Double boiler

If living without hot water is not included in the plans, then it is worth thinking about purchasing a double-circuit boiler. It differs from single-circuit in that its design provides an additional heat exchanger for heating water. Depending on the power of the boiler, it is possible to organize the heating of water and its supply to two water points at the same time. To minimize the cooling of water on the way to the points of analysis, it is desirable to locate the boiler closer to them.

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

The most popular boilers with two heat exchangers. They work independently of each other. In one heat exchanger, the heating water is heated, and the other 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 boiler, hot water comes from the boiler

Advantages of a double-circuit boiler:

• Buying such a boiler will cost less than a complete set consisting of a single-circuit boiler and a boiler.
• The boiler is compact enough.
• Water is not collected in the storage tank, but the amount of water that is needed at the moment is heated. This reduces the heat loss due to cooling.

How to choose a boiler of appropriate capacity

If the choice in favor of single- or double-circuit boiler has already been made, then it is necessary to select a boiler of appropriate performance. In order for the air temperature in the rooms to be comfortable and the temperature of the hot water at about 50 degrees Celsius, you can make a simple calculation of the power of the installed boiler. For this, the area of ​​all heated premises is summed up and divided by 10. This is the approximate load on the heating. Increasing it by about 15-20%, we have the total capacity of the boiler, taking into account hot water supply. However, as advised by professionals, the boiler should be purchased with a slightly higher capacity 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, the selection of equipment should take into account the amount of heat loss from pipelines, possible voltage drops.

Boiler manufacturers - which model is better?

In the variety of brands offering their products is easy to get confused. How to choose a boiler and not make a mistake with the choice. Now in the market of heat and power production equipment of several countries is mainly offered. These are Germany, Italy, Korea and Russia. All boilers have some differences related to the technical characteristics of the work and also significant differences in cost.
German heating boilers.

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

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

Italian heating boilers

Boilers Italian companies also have good build quality. One of the most famous Italian brands - Beretta, produces boilers of high power. In the model range, you can pick up heating equipment with a capacity of up to 24kW. It can be as single-circuit, double-circuit boilers, boilers with a built-in and free-standing boiler. A distinctive feature of the Beretta equipment is that it can work at very low ambient temperatures.

Baxi has been in the market for heating equipment for several years. During this time, experts are constantly developing and implementing new solutions. In the fifth generation boilers, an atmospheric-type burner is installed, which works almost silently. Baxi equipment is represented by a wide range of power from 10 to 80 kW. The boilers have a relatively small size and high efficiency - up to 90%.

Korean heating boilers

Korean-made boilers combine modern technology and reliability. They are equipped with protection systems against voltage surges, pressures and temperatures in the reservoirs. Also, a natural gas leakage detector is built into the boiler. When it is detected, the boiler automatics will shut off the gas supply to the burner.

Navien occupies a leading position among the manufacturers of boilers. It produces boilers working on a different type of fuel with a different number of circuits. The equipment is equipped with burner devices that operate even with low natural gas pressure. In addition, a voltage regulator is built into the boiler, which protects the system from overloads.

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

Boiler equipment company Danko regularly receives good reviews from users and experts. From the model range presented by the company in the range from 7 to 15 kW, it is easy to pick up the boiler for heating a small country house or apartment, with a permit. The boiler unit is equipped with a gas filter, a steel heat exchanger and a micro-flash economic burner.

Another company producing competitive boiler equipment, Borinskoe OJSC, IShMA BSK. A distinctive feature of these boilers is that they are available with an integrated circulating pump. At the same time work of a copper is possible both at the working pump and without it. This is very convenient with frequent interruptions in the supply of electrical energy.

What to look for when buying a boiler

1. Burner. It depends on her economical operation of the boiler. It is important that the design of the burner contributes to the qualitative mixing of gas and air, and hence the complete combustion of the fuel without chemical underburning. The most economical are automatic burners with an integrated fan. Before being supplied to the furnace, the gas is mixed with air and then fed to the boiler. The downside of this burner is the additional noise generated by the fan.
2. Heat exchanger The quality of heat transfer from the combustion products to the environment depends on the material of the heat exchanger. The best choice would 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 borne in mind that under the influence of high temperatures and corrosion, its elements often fail. The more famous the brand of the boiler, the easier it will be to pick up the part for replacement.
3. Electronics and automation. The boiler is equipped with sensors and allows you to adjust the work just by pressing a few buttons, simple and easy to operate. But it is worth considering that when the power is turned off, the protection of the boiler will work and the fuel supply to it will stop. It is necessary to choose equipment on which there is a possibility of manual regulation of its work in any cases.

According to customer reviews, the best are, in their opinion, boilers of German and domestic production. They are easy to maintain. Repair is also not difficult, since there are many service centers that order components and parts for repair directly from the factory. Coppers of the Italian brands, on the contrary, caused complaints from consumers because of the short warranty period, difficulties in repair and selection of spare parts.
It is important to pay attention to the choice of the boiler. After all, it will last more than a dozen years and will create a feeling of comfort and coziness in winter evenings.

Choosing a heating boiler in the house is a serious task. And if you have already decided on the type of fuel, then task number 2, which is facing you, is the choice of the number of circuits for equipment. And here it is necessary to understand more carefully and in detail. Surely you have a whole bunch of questions: from the advantages of each type to the ease of installation and their capabilities. We will try to make a detailed comparison of these species on several points. Ready? Go!

Difference between single and double boiler

  Installed boiler with 2 circuits

The name itself already partially gives the consumer an answer to the question: what is the difference between such boilers? Obviously - in the number of contours.

Single-circuit heating boilers can only heat the rooms of the apartment / house. They connect to the battery system (radiators) and heat the water only for them. Such a boiler does not heat water for domestic needs: the consumer will have to take care of this separately.

Dual-circuit boilers are able to both heat the house and heat the water.for washing dishes, showering and other domestic needs. Their design provides an additional heat exchanger for heating water. It is of 2 types:

• Flow Heat Exchanger   - in such boilers there is a "priority of hot water supply". If you need to take a shower or wash the dishes, then you need to set this mode: then the boiler will switch to the 2nd DHW circuit. Such models are suitable for houses and apartments of a small area (up to 70-80 square meters), since low-power heat exchangers are built into such models.
• Boilers with built-in storage boiler- The volume of the tank on average varies from 150 to 180 liters. Can heat water both in the accumulative mode, and in flowing. However, it is worth considering that in the latter case (with the flow method) the water will be slightly colder than with the storage one.

The principle of operation and the device of a double-circuit boiler

Such a model was originally equipped with an additional heat exchanger for hot water supply: in it, water from the cold-water system (cold water supply) is heated by the hot primary coolant (heating). For the organization of work the manufacturer has provided a special valvewhich controls the direction of movement of the coolant.

The principle of priority of the DHW system. Now explain what it is. When the valve is in a certain position, the heated coolant moves to the heating system, and the house starts to warm up. However, if one of the households opens the hot water tap, the boiler will immediately stop heating the water for heating the house and begin to heat it for the DHW system.

It turns out that while using hot water the heating circuit of the house is inactive. At that moment, when the hot water tap closes, the boiler instantly sends coolant to the radiators.

Thus, 2 circuits cannot work simultaneously.

Double-circuit boilers can operate at 1 or 2 points of water intake. If there are 2 points, then it is better to place the boiler approximately in the middle between them. If one - then as close as possible to her.

The fact is that it takes time to heat the water: if you open the hot water tap, cold liquid will flow first and then warm. The farther the boiler is located from the tap, the longer you will wait for hot water.

The principle of operation and the device single-boiler

  The scheme of the boiler with one circuit and two

In their design, there is only one heat exchangerwhich heats the water for the heating system. If you want it to supply you with hot water, then you will need to separately buy and install a boiler of indirect heating.

The main elements are the combustion chamberin which are located burner   and coil. On top of the last and is a heat exchanger. The fluid can circulate naturally or with a circulating pump.

By the way, all models are designed in such a way that in the future you will be able to connect this boiler to them.

In this case, the system will work similarly to the system of a double-circuit boiler: on the principle of priority of the DHW circuit   using a valve that controls the movement of coolant from one circuit to another.

Pros and cons of single boiler

  Single boiler with boiler

The most important thing that influences our choice is the advantages and disadvantages of a particular model.

pros

• Lower cost   - compared to the dual-circuit model. The cost of the purchase, installation and maintenance of such a boiler you will leave significantly less than his brother with two circuits.
• High power and efficiency. Many single-circuit models have a floor-mounted installation method, which, in turn, allows manufacturers to use a cast-iron heat exchanger instead of a steel one. And cast iron, as you know, has a higher heat capacity, which means faster and more efficient heating of the coolant, which means that such boilers can cope with heating even large areas (more than 100 square meters). In addition, boilers with cast iron heat exchanger can be used for heating systems of the old type, which is also important.
• Less gas consumption- it is quite logical, since such boilers have only 1 circuit. However, when the boiler is connected, the flow rate will significantly exceed.

Minuses

• Perhaps only home heating   - as we said above, if you buy a “bare” single-loop model, you will be provided with only heat. To be able to heat water for hot water, you will have to attend to the installation of BKN (boiler indirect heating). To do this, you will need to choose, buy, appropriate parts for its installation, etc.
• Separate room required- it is better to install the boiler and the boiler in a separate room, since the pipe decoupling system will not look very aesthetic, and it will take a lot of space.

Pros and cons of double boiler

Similar information is necessary for us about double-circuit boilers.

pros

• Small size   - since the design of boilers with 2 circuits was originally sharpened for heating and DHW, it does not need to be supplemented with anything. And this means that the model of what sizes you bought initially, it takes so much space from you.
• The possibility of placing in the back room- unlike a single-circuit boiler, you do not need to look for a place for the boiler room to place the boiler there. All pipe routing and connections look very neat and take up little space. Suitable for homes and apartments with a lack of free space.
• Easy operation- as mentioned earlier, the second circuit is responsible for heating the water. So you do not have to suffer with the selection and connection of the BKN, as well as the necessary fittings for this purpose.

Minuses

• Unstable water pressure and coolant temperature   - This is especially noticeable if the boiler is operated at 2 points of intake. Due to the not very high power of the equipment, the tap water may not always flow with a strong pressure and is not as hot as you ordered. By the way, this problem is not observed in single-circuit with a boiler
• High maintenance requirements - the second heat exchanger of the boiler (for hot water supply) is very sensitive to the high salt content in the coolant and very quickly overgrown with scale and bloom. Therefore, you need to regularly clean the equipment or monitor the content of impurities in the coolant.
• Higher cost- in comparison with a single-circuit boiler WITHOUT an indirect heating boiler. Of course, if we consider the purchase and installation of BKN, then the double-circuit boiler is cheaper.

Power and size

These are the first two parameters by which we compare our "contestants".

Power

So, first we analyze single-circuit heating boiler.

Calculate the power of the device is quite easy: 10 sq.m. Square required 1 kW of power. Plus do not forget about a reserve of 20%. Everything is simple here. However, special attention should be paid indirect heating boiler volumewhich you plan to install on a single-loop unit. It is in it that all the “salt” of choice is enclosed. If you choose a boiler with a boiler that comes in the package, then on average its volume will be 100-120 liters. With an economical consumption of this amount of water is enough for 2-3 people. However, you can forget about frequent bathing in the bathroom.

If BKN you choose separately, then here it is worth proceeding from the preferences of your household. So, for a large bath you will need a boiler with a volume of more than 300 liters.

Double boiler: its power is the most important parameter when choosing, for it depends on it what temperature and what pressure the water will flow from the tap. If you have 1 water intake point and you plan to use only a shower, then on average you will have enough of a 10 kW boiler. For those who like to periodically relax in the bathroom you will need equipment already at 18 kW But for a stable supply of water to both points of water intake, we also recommend buying a 24 kW boiler. With less power

Dimensions and compactness

As we said earlier, double-circuit heating boiler in this regard is much more practical, than single-circuit, as it is already a finished product without the need to connect something extra. It can be installed in any room convenient for you.

For a single circuit, you need to leave a lot of free space, as most likely in the future you will need to connect an expansion tank, a safety valve, a boiler itself, etc.

Equipment

  heating boiler with 1 circuit

This parameter is directly interrelated with the dimensions of the device.

Double boiler - a finished product, a mini-boiler room, in the construction of which there is already all the equipment necessary for heating and hot water supply (valve, circulation pump, valves, etc.) for the organization of the gas removal system

Single circuit boiler   - This is the basic equipment. Separately, you will need to buy an indirect heating tank, a pump, a membrane tank and other equipment to fully supply your house with heat and hot water. More complete set have a wall-mounted single-circuit boilers, which are equipped with part of the necessary components.

Features of operation of single-circuit and double-circuit boilers

Finally, we will give you some useful tips that will finally help you make the right choice.

• If you chose a double-circuit boiler, then you need to know one of its features: after opening the tap with hot water, you will have to wait a while (a few minutes) until the cold water becomes warm. This is a serious drawback, because, firstly, it is inconvenient to stand and wait until it merges. And, secondly, at this time the water meter will actively spin. That is, every time you just pour money into the sewer.

In order to somehow compensate for this drawback, experts recommend positioning the boiler from a water intake point no further than 5-7 meters. Longer distance significantly reduces the efficiency of work.

• In single-circuit devices, there is no lack of this, but there is another. If you do not immediately consume the heated water in the BKN, then it will cool and heat up again. As a result, energy will be constantly spent on its heating.

Conclusion

So which cauldron is better: single or double? There is no unequivocal answer to this question - each family chooses a device for its needs and conditions.

If you are for saving fuel and space   - then you definitely should opt for a double-circuit boiler. He begins to heat the water only when there is a need for this. For comparison: a single circuit will be turned on every few hours - when the water in the boiler has cooled.

Also, double-circuit prefer to put the residents of apartments, in which there is not so much free space as the owners of their cottages.

If you are for convenience and higher reliability   - that single circuit is your choice. No contrast shower, if the second valve is open, and a weak water pressure.

Choosing between single-loop and double-loop: video

Be sure to watch this video: it will help determine the choice:

We hope that our article has given you a rough idea of ​​these two types of boilers, and you have already made your choice. Good luck!