Choose a single-circuit or double-circuit gas boiler, the best double-circuit gas heating boilers. Double-circuit and single-circuit gas heating boilers The difference between a single-circuit and double-circuit boiler

A double-circuit heating boiler allows you to effectively solve the two most important problems for the owner of a suburban home: heating and water heating. Today, a wide variety of models of this equipment are produced, differing from each other not only in parameters and price, but also in the principle of the device.

This small educational program will help orient everyone who is thinking about buying such a boiler, but still does not know how to choose it.

The difference between a double-circuit boiler and a single-circuit

Heating boilers with one circuit are intended only for heating the heating medium circulating in the heating system. To heat tap water, the owner of such a boiler has to buy and install another unit - a gas water heater or a boiler. Comfort in this case is quite expensive: firstly, the purchase of a separate gas water heater and a heating boiler requires significant costs; secondly, two installations take up a lot of space. In this case, it is necessary to construct two chimneys for each unit separately, because if they are connected to one smoke exhaust channel, the “exhaust” of one of the devices can lock the hood from the other, due to which the products of fuel combustion will enter the room. Maintenance of two separate devices is also more difficult.

The figure shows a diagram of a single-circuit boiler device.

In double-circuit models, an instantaneous water heater and a heating boiler are assembled into one unit. Thus, the homeowner solves two problems at once, buying just one device, compact and relatively inexpensive. Accordingly, piping, maintenance and chimney arrangement are simplified.

Various models of double-circuit boilers (floor and wall) can differ significantly from each other, but the heating of water and heat carrier in them is carried out according to the same scheme. If there is no hot water flow, the heat carrier heated by the gas burner circulates in the first circuit connected to the heating system. As soon as the user opens the hot water tap, the boiler automation switches the valves so that the coolant is redirected to the second circuit. This circuit is connected to the heat exchanger of the instantaneous water heater built into the boiler, through which tap water is supplied. Thus, the working medium - the heat carrier - is used alternately for heating, then for hot water supply. This leads to one of the disadvantages of a double-circuit boiler: a significant consumption of hot water negatively affects the efficiency of the heating system.

Double-circuit gas boilers can be equipped with a storage tank for hot water - a boiler. Such devices consume more fuel and are more voluminous, but they can simultaneously serve several points of water consumption, unless, of course, hot water is constantly consumed in them. When the supply of water in the tank is used up, the user does not have to wait for a new portion to be heated, as is the case with household electric boilers. The boiler will automatically switch to instantaneous water heater mode.

What are double-circuit boilers?

Advantages of the boiler model from viessmann.

Modern models of double-circuit gas boilers may differ in the following features.

The smoke exhaust system can be convection or condensing. In the first case, the products of fuel combustion, including water vapor, from the combustion chamber go directly into the chimney, from where they are emitted into the atmosphere due to convection or, as it is also called, natural draft.

In condensing boilers, there is a heat exchanger between the combustion chamber and the chimney, which is connected to the heating circuit. This scheme allows you to assimilate additional thermal energy, most of which is formed during the condensation of water vapor.

The advantages of convection boilers include: simplicity of design, low price (gases are removed in dry form, so there is no need to use expensive corrosion-resistant materials), convective draft in the chimney makes it possible to do without a fan.

Disadvantages: relatively low efficiency: a significant part of the thermal energy literally flies into the pipe.

All the disadvantages of condensing systems - the high cost, the complexity of the device, the presence of an electricity-dependent fan - are more than offset by the main advantage: due to steam condensation, the boiler efficiency is almost doubled.

Circulation of the coolant in the system.

It should be noted that the installation of such a model on a conventional heating circuit will be unjustified. The connection diagram for a double-circuit condensing boiler is no different from the traditional one, but in order for such a unit to function with maximum efficiency, the coolant entering the heat exchanger of the smoke removal system must be cold. If the temperature difference between the coolant and the steam is insufficient, the latter will not condense. And since a working medium circulates in the heating circuit with a lower temperature than in conventional systems, it has to be equipped with larger, and therefore more expensive, radiators.

Fuel combustion chambers in gas boilers can be open or closed. Convection units are equipped with both types of chambers, condensing units - only closed ones.

What is an “open firebox”? This is a combustion chamber that uses oxygen from the air in the room in which the boiler is located. Closed - completely isolated from the environment. In such systems, coaxial-type chimneys are used, or, more simply, a pipe in a pipe. Fuel combustion products are removed through the inner pipe, and clean air is sucked in through the outer pipe. Smoke from a closed chamber, regardless of whether there is a heat exchanger (condensing boilers) in the smoke exhaust system or not (convection boilers), is only forced out by means of an electric fan. Therefore, such boilers are called turbocharged.

Advantages of boilers with an open hearth: low cost (the difference in price is quite significant), non-volatility (meaning electric energy).

The principle of operation of the heating system using a double-circuit boiler.

Disadvantages: due to the lack of oxygen in the room where the boiler is installed, it becomes difficult to breathe, there is a risk of fuel combustion products entering the room in the event of a draft failure, only a vertical chimney is required.

Taking into account the disadvantages of boilers with open combustion chambers, they are usually installed in a separate room.

Advantages and disadvantages of turbocharged boilers

Double-circuit turbocharged boilers are characterized in exactly the opposite way. Their pluses:

can be installed in any room;
absolutely safe;
smoke can be diverted in any direction.

high price;
cannot work without electricity.

Model of a turbocharged gas boiler.

Gas heating boilers are floor-standing and wall-mounted. What is a wall-mounted boiler, most buyers imagine: such boilers can often be seen in city apartments, which have autonomous heating and hot water supply. Units of this type are compact and lightweight, but limited in power and hot water performance. Floor-standing boilers have to be installed in a more spacious or even separate room, but these units have high power and, accordingly, DHW performance. A floor-standing boiler has another important advantage: since its weight, unlike a wall-mounted one, is not limited by anything, manufacturers equip it with a cast-iron heat exchanger, which is of higher quality and more reliable in comparison with a steel one.

In addition to all of the above, floor-standing boilers may differ in the type of burner. The cheapest are atmospheric burners, but they cannot boast of high efficiency, have a relatively low power and are too noisy. All these drawbacks are devoid of expensive pressurized burners.

How to choose a double-circuit boiler?

The main parameters by which the model of a double-circuit boiler is selected are the power and productivity for hot water. Let's consider each of the characteristics in detail.

Determination of the required power

Boiler components.

To accurately determine the power sufficient for the efficient operation of the heating circuit, a thermal calculation must be performed. His methodology is rather complicated, so only a heating engineer with a certain experience and a base of special knowledge can cope with such a task. Thermal calculation takes into account many factors (area of window openings, thermal permeability of walls, heat transfer from radiators, etc.) and allows you to select the optimal boiler model without overpaying for extra kilowatts. But at the initial stage, you can do without it. The required power is roughly estimated based on empirical data: on average, a heating system consumes about 100 watts of energy per sq. m of heated area. If one or several rooms border on unheated rooms, this figure can be increased to 150 W.

Determining the required hot water consumption

We remind you: if an intensive hot water consumption is planned, it makes no sense to install a double-circuit boiler, since heating in this case will be purely symbolic. To ensure the supply of hot water within the framework of ordinary household needs simultaneously with heating, a double-circuit boiler is quite capable.

To determine the required hot water consumption, you just need to summarize the water consumption at all points connected to the boiler. On average, from an ordinary water tap at a pressure in the system of 2 - 3 atm, from 4 to 6 liters of water flows out in one minute. When taking a shower - 10 - 12 liters. If the scheme provides for connecting more than three points to the water supply, you can take the total consumption not of all, but only a few of them.

Assembly diagram of the components of the heating system.

Please note: in the boiler passport, the hot water performance is tied to the temperature difference before and after water heating. Therefore, to select the optimal model, you should know not only the hot water consumption in your house, but also the temperature of cold water at the inlet to the boiler. Let's say we have two taps with a flow rate of 5 l / min of hot water, while the water temperature in the water supply system before heating is 7 degrees. Therefore, we need a boiler that provides a hot water capacity of 5 + 5 = 10 l / min at a temperature difference of 40 - 7 = 33 degrees (40 ° C is a comfortable water temperature for washing dishes, taking a shower, etc.).

An approximate calculation will allow you to determine whether it is worth spending time studying wall-mounted boilers or it is better to look at the floor-standing ones right away. The maximum heated area limit for wall-mounted models is 200 sq. m, hot water - 14 l / min. If the values you obtained exceed these indicators, only floor-standing boilers are suitable for you. In general, these units are more popular than their wall-mounted competitors. Buyers, even for low water consumption and a heated area, prefer floor-standing boilers, since such models are equipped with more reliable and durable cast-iron heat exchangers. In addition, they are less picky about the quality of the power supply.

Factors affecting the durability of boilers

Wall-mounted boilers, being more modern and complex, often fail at the slightest voltage surges. In this case, as a rule, the main board burns out, the replacement of which is very expensive. Another important point: floor standing boilers are more suited to work with poor quality water. The heat exchangers of wall-mounted boilers, which manufacturers strive to make as light and compact as possible, are a set of small-diameter tubes that are very easily clogged.

If your tap water contains too many hardness salts, pay attention to floor standing boilers with a boiler. Such units are not afraid of salt deposits and provide hot water supply even during peak hours, when the pressure in the water supply system drops significantly or completely disappears.

Buyers who are often faced with an emergency power outage should choose non-volatile double-circuit boilers. These, as a rule, are floor-standing models with an open combustion chamber. The burner ignition mechanism is of great importance. A more convenient and economical electric ignition in this case will be inappropriate, since it is also not able to function without power supply. The model with manual or piezo ignition will be optimal. The burner in boilers of this type ignites from a constantly burning gas wick. The disadvantages of such systems are the increased gas consumption and the inability of the boiler to automatically resume operation after a temporary drop in pressure in the gas supply system.

A double-circuit boiler is a very complex equipment, and many of the features of a particular model can only appear during operation. Therefore, before purchasing this device, we recommend that you carefully study the user reviews published on the Internet.

Reading time: 52 min

As they say, any medal has two sides. Almost every decision we make in life has its pros and cons. All this is also true with regard to the choice of the type of boiler. There is no definite answer to the question of which heating boiler is better. There are only advantages and disadvantages of these boilers, as well as your circumstances and opportunities. How can you find the golden mean in all this? Let's figure it out together.

The very title of this review is based on the idea of comparison. Therefore, along the way, we will compare both types of boilers with each other and look for their differences in order to better understand and understand their features.

So, the first and perhaps the most obvious difference is concluded in titles, which fully reflect the essence of the operation of these devices.

Single-circuit boilers are intended only for space heating... To do this, it is enough for them to have a connection to only one circuit (or circuit) of radiators or other heat exchangers connected to each other (in parallel or in series). The heating system in your home may be relatively simple, but its heart is a single-circuit boiler, it doesn't have to look and work like a "potbelly stove". Modern single-circuit boilers are electronically controlled, and their operating parameters can be adjusted very finely.

Double-circuit boilers, as the name suggests, can do more than their single-circuit counterparts. Such boilers are capable of operating on two independent branches of heat and water supply, one of which is your batteries, the other is water faucets in the kitchen or bathroom. Our heart also works in two circuits, driving blood through the lungs and through the rest of the vessels of the body. However, unlike the perfect work of the heart, double-circuit boilers cannot work simultaneously on two circuits. So, all the time while you are using hot water in the shower, the coolant in the heating pipes will not heat up. And as soon as you turn off the hot water tap, water heating in the heating system will resume.

The principle of operation of a double-circuit heating boiler.

The completeness and the possibility of optional use of heating equipment are also excellent.

Usually, double-circuit boilers are delivered completely ready for operation and to the fulfillment of their main tasks. Do not connect any other water heating equipment to them. But this, however, does not need to be done. Having picked up a boiler of the required power (more on that below). You immediately provide yourself with warmth and hot water. That is not much that you have to do - it is to organize the supply of fuel (gas), the removal of combustion products and the connection of pipes with water (heat carrier).

Of course, this will also need to be done when using a single-circuit boiler. In this case, you will also need to install an expansion tank, a pump to improve the circulation of the coolant in the system and a safety valve. But even a single-circuit boiler can be used like a double-circuit, if you slightly "finish" the system.

Suppose you have the entire set of equipment and components necessary for the operation of a single-circuit boiler. In order for the same boiler to heat water for domestic needs, an indirect heating boiler is installed next to it, since the design of many modern single-circuit boilers allows such a connection. Heating the coolant for hot water supply in such a boiler is called indirect, since during its operation there is no direct direct heating of the liquid in the tank. A coil is placed inside the boiler(or several coils) through which the coolant heated by the boiler flows. The coil itself, in turn, heats the water in the boiler. The downside is that with indirect heating, a particularly high water temperature cannot be achieved. However, to comfortably shower or wash the dishes, this will be sufficient.

Connection diagram and operation of a single-circuit boiler and an indirect heating boiler.

Dimensions and power

I must say that double-circuit boilers are often more compact than single-circuit. This is a significant plus if the dimensions of your home force you to take into account every free centimeter. In view of this, single-circuit boilers are more suitable for installation in a private house, when the boiler can be placed not in the kitchen, but in a separate utility room.

When choosing a boiler, it is important to choose the right power for it. In this case, you can contact the specialists, but you can calculate the boiler power yourself, because the calculation formula is extremely simple: to heat 1 m2, you need 100 W of power, plus ten percent. Let's say your home is 75 square meters. Multiply this number by 100 - we get 7500 watts. We add ten percent of the power and we get 8250 watts. Therefore, your boiler should have a power rating close to 8.3 kW.

However, if you use a single-circuit boiler together with an indirect heating boiler, the boiler output must be much higher and can be up to 20-24 kW. As a result, the water in the boiler will heat up quickly, and the coolant, which does not heat up by itself during the heating period of the boiler, will not have time to cool down noticeably.

Of course, all these are just average calculations. Much depends on what climate zone you live in, whether your house is insulated, what kind of windows you have and what condition they are in, and so on. It can only be noted that with an increase in the area of \ u200b \ u200bthe dwelling, the required boiler power decreases in proportion. This happens, for example, due to the fact that the larger the house, the more rooms in it that do not have external walls or windows. Accordingly, the heat loss in such rooms is an order of magnitude less.

Both among single-circuit and among double-circuit boilers, you can choose the one that will meet your needs. but single-circuit boilers are generally more powerful than double-circuit... Therefore, if you have to heat large areas, you can give preference to a single-circuit boiler.

At the end of this small excursion, it is worth highlighting several nuances that affect the choice of boilers:

when using a double-circuit boiler, it takes some time wait for hot water to flow(in this case, your money will flow into the sewer together with the water); experts recommend that the farthest draw-off point be no more than 5-7 meters from the boiler, otherwise the efficiency of hot water supply can be questioned. When using a single-circuit boiler with an indirect heating boiler, the water from the tap flows hot immediately, but if it is not consumed all and not immediately, it turns out that most of the time heating occurs idle
the pressure (pressure) of hot water in the tap will change if, in addition to you in your house, someone else opens the hot water tap; this can be very annoying, especially when showering, when cold or hot water is not coming out of the mixer
a secondary heat exchanger (the one that heats water for domestic needs) in a double-circuit boiler is more susceptible to mineral overgrowth due to a small clearance and running, unsettled water
in general, for obtaining hot batteries and hot water supply, installation of a double-circuit boiler is cheaper than a system of a single-circuit boiler and an indirect heating tank, serving the same purposes
double-circuit boilers save space and can be both floor-standing and wall-mounted; for single-circuit boilers, you will most likely have to allocate a section of the floor in the kitchen or other room (although wall-mounted options have also appeared recently); in most cases, under a single-circuit floor-standing boiler, you need to arrange a special platform (deepening or elevation)
single-circuit heating systems are easier to operate and cheaper to repair; the average fuel (gas) consumption of single-circuit boilers is less than that of double-circuit

So what to choose, a single-circuit boiler or a double-circuit one? Any of your decisions should be based on your actual circumstances: the size of the living space, the thermal conductivity of the outer walls of the house, climatic conditions, your preferences in comfort. It is also impossible to say unequivocally that any heating system is better, just because your friends have one installed. Consider all the advantages and disadvantages of each option, ask the specialists, take an interest at the points of sale of heating equipment. Be sure to take into account the performance of the system and not only its installation cost, but also how much it will cost you to operate it.

What is the difference between a single-circuit and a double-circuit boiler? Video

When building a country house, a summer residence and deciding on a heating system, the question arises of choosing a boiler.

In areas where it is possible to bring natural gas to the house, gas boilers are used not only to heat the house, but also to organize hot water supply.

Gas boilers are one of the most popular on the market, since the total cost of heating a room and hot water heated with gas is quite low. In addition, installation is available, and the cost of gas is much lower than electricity or coal.

Thinking about purchasing a boiler, it is easy to get lost among the wealth of choice offered by the market. Condensing and conventional, single and double-circuit, with different control systems and different installation and maintenance conditions - making the choice is not so easy. When choosing a gas boiler, one should first of all build on the needs of the family. What areas are you planning to heat and how much? What volumes of hot water are you planning to consume per month? Gas consumption, the size of the boiler and a number of other factors will depend on this.

The indisputable advantage of most modern gas boilers is an automated control system, with which you can make the operation of the boiler not only convenient, but also economical.

Double-circuit boilers have a large number of functions, while being convenient and compact. They are ideal for one-story and small two-story homes where there is only one bathroom. As a rule, they are installed in the kitchen, but at the same time not far from the bathroom. It is quite difficult to heat large areas with one double-circuit boiler. If the task is to provide two bathrooms with hot water at once, you will also need a mixer.

Floor-standing and wall-mounted boilers

For a small house where one family lives, the ideal option is, as a rule, a wall-mounted boiler. It's compact, easy to use and, most importantly, doesn't take up such valuable living space. Often, wall-mounted boilers are hung in the kitchen or bathroom at head level or under the ceiling to free up space on the floor against the wall for household needs.

If the consumption of hot water and heating needs are very high, it is recommended to install a floor-standing boiler. Units with a capacity of over 30 kilowatts and a volume of more than one hundred liters exist only in floor-standing versions. The reason is quite simple - not a single wall can withstand such a weight, and the boiler is so large that it resembles a small refrigerator in volume. Often these are oversized or separated by a partition.

Diagram of the heating system, hot water supply, underfloor heating systems with a wall-mounted boiler

What are such large floor standing boilers for? They are able not only to heat large areas and provide a significant amount of hot water, but they can also handle a large volume of coolant without installing a boiler - that is, in fact, they significantly save space and installation costs.

Condensing and conventional boilers - what to choose?

When a similar question arises when choosing a unit, those uninitiated in technical details are usually lost in the choice. The difference, however, is very simple. An ordinary boiler, generating energy when processing fuel, does not use the entire resource obtained. Part of the energy is lost "on the way", goes to heating the boiler and is removed along with the combustion products, without bringing any benefit. Of course, such an approach is uneconomical, therefore, if the amount of gas consumed by the boiler is of fundamental importance for you, it is better to give preference to condensing boilers.

The latter, in order to use the hot water vapor formed during the heating of the heat carrier, cool the resulting gas and use the resulting steam condensate. Thus, the efficiency of condensing boilers does not fall below one hundred percent.

Manual and automatic adjustment - pros and cons

In order to be able to adjust the operation of the boiler to the temperature drops, a prerequisite for any unit is the ability to change the temperature regime. The simplest, but at the same time reliable way - using a thermostat... When a certain temperature is reached, the boiler itself stops working, and itself resumes it if the coolant cools down. This method practically does not require human intervention and is comfortable if there is a need to maintain a stable temperature in the room. There are certain ones that need to be followed.

But if it is necessary to vary the temperature of the batteries with respect to the time of day or days of the week, here new generation units come to the rescue - programmable gas boilers... You can set the required temperature and its difference at different times manually or using sensors. The latter are used to read weather changes and, accordingly, increase or decrease the temperature of the coolant, depending on the warming or cooling. By the way, with the help of programs, you can set different temperature modes for wall-mounted batteries and underfloor heating, if such a function is provided.

Programmable gas boilers of the latest generation are developed taking into account Smart Home systems. This means that you can set a program for them from a distance using a smartphone or remote control. Such a system is very convenient for country houses in which they do not live permanently. Before arriving on the weekend, you can give the system a turn-on signal and set the desired temperature - by the time the owners arrive, the house has time to warm up, but this does not waste a resource, as if the room had been warming up all week.

As a rule, it occurs on the eve of the heating season, and therefore the settings set by the installer do not change for a long time. Before the start of the next heating season, the boiler must be inspected and serviced by a specialist. He checks the integrity of all systems, if necessary, cleans the chimney and adjusts the boiler.

When choosing a boiler, one should take into account not only one's own needs and its economy, but also the possibility of its quick repair, the availability of service and the availability of parts for units of this type on sale. Therefore, it is best to choose a reliable mid-price boiler from a manufacturer with a proven reputation, and not chase after cheapness.

When choosing a device for heating a private house or cottage, it is important to understand that single-circuit and are still different devices. Which one is suitable specifically for your case, you need to decide based on the characteristics and advantages of each boiler.

Someone needs a device strictly for heating, and in some houses it is also necessary to heat the water with something. Therefore, the question arises about the type of gas boiler. Which is better: a single-circuit or double-circuit gas boiler, each user chooses for himself. But the consultation of a specialist will not be superfluous.

The main differences

The main difference between a double-circuit and a single-circuit gas boiler from each other is that one is intended strictly for heating, and the second has a flow-through water heating system in its structure and, in addition to heating, also provides the house with hot water.

By its structure, a double-circuit boiler is a double device. He, with the help of water heating, provides hot water supply, while a single-circuit boiler can only heat water with an additional connection of the boiler.

The name of these devices indicates their main difference. In a single-circuit - one coolant circuit, and in a double-circuit - an additional source of water heating. In this case, double-circuit boilers can have one or two heat exchangers. In the first version, there is a switch that turns off the gas supply for heating and supplies it for heating. In the second case, there are separate heat exchangers that heat water for heating and water supply.

After buying a house, before buying a boiler, you need to draw up a gas project that will allow the placement of such equipment in the house. Then it is imperative to study what a single-circuit and double-circuit gas boiler is, consult with a specialist, and also weigh the need for a certain heating option.

The double-circuit version is also divided into several types. It can have a heat exchanger, which consists of several bent tubes with plate elements. There is also a bithermal heat exchanger that looks like a honeycomb device. The latter model is best used where there is no high water hardness.

Benefits of both

Each version of the boilers has a number of features, both positive and negative. They must be considered so that an adequate decision can be made on the installation of a specific boiler model. The advantages of single-circuit models:

They have an automatic security system. It is possible to configure the most acceptable mode of gas consumption and boiler operation.
On the basis of such boilers, you can create various heating systems with wiring throughout the premises.
The presence of special sensors for climate regulation. They help to increase or decrease gas flow and heating, depending on the ambient temperature.
Reliability and ease of use.
Long service life.

All these advantages allow many to make a choice in favor of the single-circuit version. Plus it's cheaper than most dual-circuit models.

But do not forget about the advantages of a double-circuit boiler:

It will cost less than a single-circuit boiler and a boiler at the same time. If you want to provide your home with hot water, then the cost of this option is more profitable.
The water heats up constantly and does not accumulate in the tank, such as in a boiler. It heats up exactly the amount you need, and there is no heat loss due to cooling.
The model is small in size and fits comfortably in a modest room. Under certain conditions, it is possible to install the device even in a non-residential area.

Of course, everyone will choose a boiler for themselves, depending on personal preferences, but it is better to calculate the required power in advance so as not to overpay for too powerful options.

This indicator depends on the area of the heated premises, as well as on the required constant temperature and the number of people who live in a given house. Many experts recommend, if you need hot water supply, to buy a single-circuit boiler and a storage tank for heating water 200 liters. Someone advises to combine a single-circuit boiler with a gas water heater.

Disadvantages of both types of boilers

The option that suits one buyer is completely unacceptable for another. Therefore, before choosing the best heating option for yourself, you need to evaluate not only the pros, but also the disadvantages of all boilers.

Cons of using a single-circuit boiler:

Heating water requires an additional device that can be expensive and take up a lot of space. Very inconvenient in small houses.
When using an additional device for heating, a single-circuit boiler will constantly consume gas in order to maintain a normal water temperature. As a result, more gas will be spent, which will hit the consumer's wallet.

Disadvantages of a double-circuit device:

It is necessary to maintain a balance between water flow and heating, otherwise unstable temperature will occur. If several taps are turned on at once, the hot water jet may not be satisfactory.
When using water with a high degree of hardness, salt deposits can build up and damage the appliance.
Waste water consumption, since after switching on it will take several minutes to heat it up.

As a result, when comparing two devices, it is recommended to focus on the area of the room. For example, for a small country house, it is better to buy a two-circuit compact model that will take up little space and will be able to provide such an area with both heating and water heating.

Important: but if you have a large cottage of several floors, then it is better to have a single-circuit boiler, and a large storage boiler to it. This guarantees a stable water temperature and sufficient quantity. you can read which boiler is better to choose for heating in a private house.

Owners of private houses have an age-old dilemma - which is better: a single-circuit boiler or a double-circuit boiler? To understand this, you need to remember what a contour is. In the world of gas boilers, there are only 2 circuits. Everything that transfers heat from the boiler to the house is the heating circuit. These can be radiators, warm floor systems or warm skirting boards. Regardless of how many circuits there are in your "warm field", it will still be just one heating circuit. In turn, everything that brings hot or cold water into the house is considered a hot water supply circuit.

So, we have decided that there can be only two contours. If the boiler inside itself can heat both heating liquid and hot water, then the boiler is called double-circuit, that is, there are two circuits inside the boiler. At first glance, it may seem that such a boiler is the ideal solution for our home. After all, inside one unit we get both heating and preparation of hot water. In addition, as a rule, double-circuit gas boilers are cheaper, but let's not rush to conclusions. First, you need to understand the internal structure of a double-circuit boiler.

Single-circuit boiler designed in such a way that it is designed to heat water for heating. But at the same time, this type of boiler can also heat hot water. True, for this you need an indirect heating boiler.

The indirect boiler is a large thermos that does not give off heat to the outside. A radiator in the form of a coil is installed inside it, into the cavity of which heating fluid is supplied, and thus the water is heated. In fact, a single-circuit boiler prepares hot water in a remote boiler in the same way as a double-circuit boiler does in a plate heat exchanger. As well as a unit with 2 circuits, a single circuit allows you to select the DHW temperature and maintain it at the required level. The water connection to the indirect boiler is made with a sufficiently large pipe, at least 3/4 inch in diameter. This means that at the same pressure, 3 times more water can pass through it than through a double-circuit boiler. Accordingly, the owner gets the opportunity to use three points of water consumption at the same time. At the same time, not a single consumer will feel the inconvenience.

Today, all modern boilers are equipped with devices for connecting an indirect heating boiler.

Double-circuit boiler It is designed both for heating water for heating and for providing hot water supply. Good manufacturers install two heat exchangers. The primary works by heating the heating system. Secondary (aka lamellar) heats hot water. If at the moment a person does not use hot water supply, then the heating fluid, heating up in the primary heat exchanger, enters the heating system and heats the radiators or the warm floor. But as soon as the hot water tap in the kitchen or bathroom opens, the heating liquid begins to move in a small circle inside the device, that is, after the primary heat exchanger it enters the plate heat exchanger.

Its design resembles a "puff cake", one layer of which is moving cold water coming from outside, towards it the heated liquid from the heating system moves. These layers are separated by thin stainless steel plates. The heating liquid transfers thermal energy to the incoming cold water, therefore, it cools down and rises up for the next heating. The incoming cold water, in turn, taking heat, leaves the secondary heat exchanger already heated. This is how water is heated in a gas boiler with two circuits.

Disadvantages of double-circuit boilers

A reasonable question arises: if we received both heating and hot water supply in one boiler, what is wrong with it? There are some interesting nuances.

The fact is that in such a unit, the connection of cold water, like the outlet of hot water, is made using a pipe with a diameter of 1/2 inch, and it is quite thin. Despite the fact that the thread at the inlet to the boiler can be 3/4, everything remains inside the boiler, that is, 1/2 inch. This means that a small amount of both cold and hot water can pass through such a pipe. Even if the power of the boiler is increased, this will not lead to a different result - all the same, the inlet diameter inside remains unchanged.

As a rule, the exact same pipe fits to a faucet in a kitchen or bathroom. According to the laws of physics - water flows where it is easier for it. And this means that if someone takes a shower in the bath, and at this time a tap is opened in the kitchen in order to wash the dishes, cold water will go to the person standing in the shower. The point here is not in the insufficient power of the boiler, but in its design. Due to the fact that the pipe in the boiler is narrow, unfortunately, it will not be able to pass a large volume of water through it. Owners of private houses should not listen to the stories of consultants that such a device is designed for 2-3 or even 4 hot water points. Remember, in reality, a double-circuit gas boiler is designed for only one hot water point.

In addition to the limitations on the volume of hot water supply, a 2-circuit boiler also has a serious disadvantage - it is the need to wait until hot water reaches the tap. As mentioned earlier, initially the boiler operates on the heating system, and in the summer it is completely idle. When the hot water tap is opened, the boiler “sees” that the water has started to move, and only at this moment, it “understands” that the water needs to be heated. In addition, he makes some pause, implying that if the consumer accidentally opened the tap, then it will be closed immediately. If it does not close within 2-3 seconds, then the boiler turns on to supply DHW.

After switching on, the device needs about 3-4 seconds to warm up the secondary heat exchanger. Thus, a few seconds are wasted for waiting and some time for the heat exchanger to warm up.

After that, hot water begins to flow into the pipe, but it takes time to make its way from the boiler to the tap. Accordingly, the greater the distance from the bathroom or shower room to the boiler room, the longer you have to wait for hot water to flow. This means that in real conditions, in the presence of a double-circuit gas boiler, after opening the DHW tap, you will receive hot water in about 15-20 seconds.

Summing up: in this case, the consumer is forced to wait for the supply of hot water, while it is possible to fully use only one point of water consumption. Moreover, it will take more than one day to put up with this, but the entire service life of the unit (on average 10-15 years). It is worth considering whether it will be comfortable?

About dimensions

Taking into account the fact that an indirect heating boiler and other equipment are not required for a double-circuit boiler, then it takes up much less space.

Outwardly, both double-circuit and single-circuit boilers are comparable in size.

You can safely install a double-circuit boiler in the kitchen. You can hardly put a single-circuit one for heating water and providing heating.

So when comparing a single-circuit or double-circuit boiler in terms of dimensions, then there is parity.

About service life

The likelihood that a double-circuit boiler will fail is higher than that of a single-circuit boiler due to more frequent use.

About savings

A double-circuit boiler is cheaper to purchase, since there is no need to purchase additional equipment for heating water.

As for the costs of energy resources, then everything is not so simple. In theory, double-circuit boilers are more economical, because they turn on only when you turn on hot water.

A single-circuit boiler, on the other hand, needs to constantly heat up the indirect heating boiler. But at the same time, modern boilers cool down very slowly. But the consumed water in the boiler must be reheated.

Comparing a single-circuit and a double-circuit boiler in terms of efficiency, taking into account the heating of hot water, we are inclined to believe that a single-circuit boiler will be more economical in the house.

About usability

What to choose for those who are not accustomed to put up with discomfort, and still want to use the benefits of civilization with convenience? For these purposes, single-circuit boilers are created as opposed to double-circuit ones. Such a device is designed to heat a heating liquid, but if you connect an indirect heating boiler to it, you can get a modern efficient DHW system.

Further, with the use of a boiler, the following can be noted: the boiler begins to heat the water only from the moment it starts to cool down for some reason. This means that it is possible to create a special recirculation system, i.e. the movement of hot water in a circle. The water will bypass each tap and return to the boiler for further heating. In this case, we get hot water immediately after opening the tap - after all, the water will already be there. This is very important if you plan to build a large house in which there will be several bathrooms, and they are far enough from the boiler room.

Outcome

Which boiler should you choose? Buy an inexpensive double-circuit boiler or invest in a serious system, in comfort and buy a single-circuit boiler with a boiler? The decision here, of course, will remain with the consumer, but it will be useful to take into account the following recommendations:

if your house is less than 150 sq m and there is only one bathroom in it, then you can safely buy a 2-circuit gas boiler. Firstly, it will save a lot of valuable installation space. Secondly, in a small house, as a rule, the distance from the boiler room to the bathroom is small. Accordingly, you can get hot water in the tap rather quickly. Again, when the system is already assembled and designed for a double-circuit boiler, there will be no advantages when installing a single-circuit boiler with a boiler.
if you want to take care of the comfort of living in advance for the coming decades, then the unambiguous choice is the "single-circuit boiler plus indirect heating boiler" system. Let it cost a little more, but the comfort of hot water supply is guaranteed in this case. This is just the case when you should not save on yourself and your loved ones.