Which is better, a double-circuit or single-circuit gas boiler: features of design and operation

Are you choosing a gas boiler to install an autonomous heating system in a private house or apartment? Agree, I want to choose the best equipment that can provide you and your family with hot water and heat during the cold season. But you just can’t decide what is better to buy - a double-circuit or single-circuit gas boiler?

We will help you understand this issue - the article discusses the features of double-circuit and single-circuit equipment, their main advantages and disadvantages, and the subtleties of using each of them. A comparison of two types of boilers was also made, thematic photos and video recommendations were selected for choosing the best option, based on the individual needs of a potential buyer.

Design and operating features of boilers

Modern gas boilers, depending on the number of circuits, can be single-circuit or double-circuit. They are externally and structurally similar, but are designed to solve different problems, and under different conditions.

As a result, it can be argued that both types of equipment are equally useful and effective, so there is no better one among them. So it all depends on the right choice. Next, we will look in detail at how the single-circuit type of gas boiler differs from its double-circuit counterpart.

Differences in the design of single- and double-circuit units

Products that belong to both types of equipment mostly consist of the same components.

The detailed design of a modern single-circuit wall-mounted boiler and the design diagram of its double-circuit “brother” are shown in the following figures:

Any single-circuit boiler is characterized by structural simplicity. Which makes them more reliable and affordable. But the listed advantages are offset by the need to buy a boiler

The presence of a complex heat exchanger and a three-way valve in a double-circuit unit makes it fundamentally different from any single-circuit analogue

The main components of the two types of boilers are similar - both the name and the purpose.

Thus, similar elements of single- and double-circuit equipment:

• cold water supply pipelines;
• gas-burner;
• membrane tank;
• chimney.

Even the structural element intended for heating water is called the same - a heat exchanger.

But, if you look at it, it turns out: the name is the only thing that makes the specified unit similar in different types of boilers - the heat exchanger of a single-circuit unit is a pipe that serves to effectively transfer the heat released during gas combustion to water.

An important difference between double-circuit boilers is that they are equipped with everything necessary for heating rooms and hot water supply. Therefore, there will be no additional costs for the purchase of equipment, and they also allow you to save space

But in the case of its double-circuit analogue, everything is not so simple, since its heat exchanger is structurally more complex. Moreover, such products are divided into separate subspecies and are bithermic And double.

In the first case, the structure is a pipe placed in a similar product of a larger diameter. This feature allows you to create 2 circuits, one of which is designed to transfer heat to the liquid used for heating, and the second for the hot water supply system.

The double heat exchanger consists of:

• pipes, which provide heating of water for heating;
• plates, transferring heat to liquids for water supply.

That is, the heat exchangers of double-circuit boilers differ in design complexity solely because of the need to solve 2 problems.

But still, the most significant difference between single-circuit and double-circuit products is the presence in the design of the latter three way valve. The purpose of which is to change the direction of hot water.

So in the standard position the valve is in a position in which the coolant is supplied only to the radiators. Everything changes when the hot water tap opens. Since the three-way valve, having received the corresponding signal, moves to another position. Namely, in the supply of hot water.

In this case, the supply of coolant to the radiators is stopped, and in full - the premises will not be heated throughout the entire time the hot water is used for domestic purposes.

That is, the design of a double-circuit boiler allows it to supply hot water only in one of two modes. But still, such a feature should not be considered a weak point of the equipment.

Comparative review of gas boilers

Both types of equipment presented are used to heat the coolant to heat rooms and buildings.And this is where the functionality of single-circuit boilers is limited.

A single-circuit gas boiler serves exclusively to heat the coolant entering the radiators of the heating system. But if you add an indirect heating boiler to it, then it, like its double-circuit analogue, will be able to provide hot water supply

Their double-circuit analogues are additionally used to provide hot water supply to solve any household problems. That is, they make it possible to take a shower, perform any other hygiene procedures, wash dishes, etc.

Next, we will conduct a comparative review of single- and double-circuit boilers according to a number of criteria.

As you can see, to organize hot water supply in the presence of a single-circuit boiler, you will have to buy additional equipment. Eg, indirect heating boiler. And these are additional expenses.

Moreover, after purchasing a boiler, it must be installed and connected correctly. We described in detail how to do this correctly and what to consider when operating such devices. this article.

Advantages and disadvantages of equipment

Both types of gas boilers are easy to operate, efficient and durable. They also have an attractive appearance.

The design of each type of gas boiler is designed to meet the needs of different categories of users, which clearly demonstrates their advantages and disadvantages. They also provide an opportunity to understand the differences between a single-circuit gas boiler and its double-circuit counterpart, helping the potential buyer make the right choice.

Pros and cons of single-circuit units

Such products are capable of providing stable heating of rooms of any size, number of floors, and distance from the heat exchanger.

And, in addition, single-circuit boilers:

• more reliablethan their double-circuit counterparts, the design of which is more complex, which leads to a slightly larger number of breakdowns;
• easier to maintain, which is also caused by design features;
• cheaper.

An important advantage is that single-circuit units can become the basis for connecting other equipment. This will expand their functionality and increase the comfort of living.

You should always remember that if you need to provide hot water supply in the premises, you will have to buy a storage boiler together with a single-circuit boiler. And this will lead to considerable additional costs. And a set of the listed equipment will take up a lot of space, which can be critical for small apartments

Connecting storage boilers will provide the premises with hot water supply. Moreover, the water will be supplied hot at any time, which is not always possible to achieve from dual-circuit analogues

This type of equipment, in the absence of the need for hot water supply, has no pronounced shortcomings. But otherwise, the lack of universality immediately affects. Which leads to the need to purchase an additional electric heating device.

As a result, its joint operation with a single-circuit boiler leads to:

• high costs for purchase, installation, maintenance;
• limited amount of water for domestic needs - boilers are most often purchased for joint use with single-circuit units, so the question may arise about the rational consumption of water, the volume of which depends on the capacity of the storage tank;
• greater load on the wiring.

The last drawback is relevant in cases where the house or apartment has old wiring or powerful electrical equipment is used in parallel. Thus, it may be necessary to modernize the electrical wiring and cable selection larger section.

You should also know that a set of a single-circuit boiler and a boiler takes up a significant more spacethan one double-circuit boiler.And with limited space this can be a significant disadvantage.

Advantages and disadvantages of double-circuit boilers

Units that belong to the specified type have some restrictions, but are still capable of providing hot water to two systems at once (heating, hot water supply). They also take up less space than their boiler counterparts. As a result, double-circuit boilers are more convenient to use.

Both types of gas boilers are easy to operate, efficient and durable. They also have an attractive appearance.

In addition, the competitive struggle of manufacturers has led to the fact that the difference in the cost of both types of units is gradually leveled out.

Therefore, today you can find a double-circuit boiler whose price is slightly higher than that of a single-circuit product. Which in some cases can also be considered an advantage.

If we talk about the disadvantages of double-circuit boilers, the most important is the inability to instantly provide hot water of the same temperature to all water consumption points in a house or apartment.

So, in their heat exchangers the amount of water that is needed right now is heated. That is, no stock is created. As a result, the water temperature may differ from what you expect or may change as you use it. This happens when the pressure or pressure changes, for example, after opening/closing the second tap.

When using a double-circuit boiler, the water temperature often differs at two different water intake points - hot water can be delivered to the desired point with a significant delay. Which is inconvenient and leads to additional costs

As for the installation, then installation of double-circuit boilers - This is a more complex procedure, especially at the design stage. Since you will have to follow numerous manufacturer’s recommendations

Which boiler is better to choose?

When choosing the best boiler, you should keep in mind that each type of equipment is designed for specific conditions. If followed, they will show maximum efficiency, allow you to achieve the expected result and mitigate shortcomings.

Therefore, it is so important to determine your requirements and take into account living conditions. So, if the equipment is selected for the apartment and there is no extra space for installation, then the ideal option would be double-circuit wall-mounted boiler. And although it is inferior in power to floor-standing models, it is quite capable of meeting the needs of residents.

For a dacha or a private house where there is a separate room for a boiler room, an excellent solution would be to install a floor-standing single-circuit gas boiler in conjunction with a boiler of the required volume. This will ensure that the family needs hot water and heat.

When installing any model of a floor-standing single-circuit boiler with a boiler, an order of magnitude more space will be required than for double-circuit analogues. And the load on the equipment in this case will be higher, so it is important to correctly select the required boiler power

If you are selecting a heating unit for a country two-story house or cottage, then in this situation it is best to choose a powerful one. double-circuit floor-standing boiler with built-in large volume heater.

Floor-standing gas boilers with one and two circuits are different more power from their wall “brothers”. They are also most often non-volatile. This is quite convenient, especially if there are power outages in the region.

We have provided more recommendations and important criteria for choosing gas boilers in next article.

Conclusions and useful video on the topic

This video will help you understand the features of different types of gas boilers:

The video material is intended to deepen your knowledge on the topic and help you make the right choice:

When choosing between a double-circuit boiler and its single-circuit counterpart, you should not wonder which is better. Since all of the above equipment is modern, productive and durable, but, as mentioned above, it is designed to solve different problems. Therefore, it is so important to take into account personal needs and living conditions so that the equipment does not disappoint you.

How many circuits does your gas boiler have? Share your impressions of using your heating equipment - tell us whether the selected boiler satisfies all your needs or for some reason you consider your choice to be wrong? Add a photo of your gas boiler, indicate its pros and cons discovered during operation.