Double-circuit boilers are the most popular on the market today. This is due to many factors. The most important of them is that a device with two circuits performs several functions. Let's take a closer look at what a double-circuit gas boiler is. We will also touch on the operating principle of the device, as well as the connection diagram and operating instructions. This article is suitable for those who want to understand this issue in more detail.
Some general information
A double-circuit gas boiler, the principle of operation of which we will now consider, can cope with two tasks at once: firstly, heating and maintaining the set temperature of water for the heating system, and secondly, heating the medium for use for economic purposes. Thus, your home is not only warm, but also has hot water. This is what it is significant difference double-circuit boiler from any other. A simple conclusion can be drawn that the design has two high-performance heat exchangers, each of which performs its own function. In addition, a double-circuit gas boiler can be of different power. Today on the market there are models from 12 to 35 kW. This is quite enough to heat a large room of 350-400 square meters. The productivity of most models ranges from 8-12 liters per minute.
About the advantages of double-circuit boilers
It is safe to say that these units have much more advantages than disadvantages. Now we will look at all the advantages. Firstly, this is a significant gas saving. This was achieved through the use of modern heat exchangers. By the way, it made it possible to make the operation of the units completely silent, so a double-circuit gas boiler can be installed in any convenient place. Dimensions in most cases allow installation without any problems. If it doesn't fit floor option, then it is always possible to install the device on the wall, which is especially important for small apartments, where everyone square meter important. The operation of a double-circuit boiler is completely autonomous, which is facilitated by the appropriate equipment (pump, computer and security system).
A little about the cons
Nothing lasts forever, and nothing is perfect. A double-circuit boiler has several disadvantages. Firstly, it should be noted that there is a noticeable loss of water during initial stage. Let's look at specific example. Now you turn on the hot water, the additional coolant automatically starts working. For hot water to flow, you need to wait about 30-40 seconds, depending on the brand of the boiler. Everything that comes out of the tap before this time is called loss. We can say with great confidence that this is not such a big drawback. If you need to heat the medium for household purposes, then a double-circuit gas boiler does this in flow mode without the possibility of accumulation. Let's go further and talk about how the unit works.
Double-circuit gas boiler: principle of operation
As noted above, the device can operate in several modes. If a single-circuit boiler is intended only for heating a room, then a 2-circuit boiler can also heat water, but this has already been said. If you need to heat a room, then the principle of operation is as follows: the carrier, in our case it is water, enters the heat exchanger, which heats it to a certain temperature. Today the range hovers around 35-85 degrees Celsius. The thermostat starts heating mode automatically. This is done when the temperature in the system drops below normal. As a result, it starts working circulation pump and supplies water from the heat exchanger (preheated) to the system. The pressure in the system is also taken into account, which should not fall below 0.5-0.7 Bar. If necessary, the microprocessor sends a signal to the burner, which heats the media until desired temperature.
The principle of operation of the boiler: part 2
But it doesn't end there. After switching on, the boiler begins to work progressively. At first at minimum power, and over time it reaches its maximum. When the dual-circuit heats the medium to a given temperature at some stage, the unit goes into modulation mode. If, when turned on for the first time, the power exceeds the permissible value, the microprocessor sends a signal to turn off the burner. It turns on again after three minutes. The combustion chamber is metal and has a special heat-resistant winding. There is a heat exchanger above it, and a burner below it. The latter lights up exactly at the moment when the temperature of the medium in the system drops and the water needs to be heated. Together with it, a circulation pump is also put into operation, designed to circulate water through a closed system. When the set temperature is reached, the gas wall-mounted double-circuit boiler switches to In some models, the burner burns, but at a minimum, while in others it goes out and lights up when gas is supplied.
A little more about the features of the work
To prevent media from entering the second circuit, a three-way valve is used. In this way, it was possible to achieve the supply of heated water from the boiler to the system through one line (supply) and return through another (return). It is worth paying attention to the fact that the gas wall-mounted double-circuit boiler is designed in such a way that the carrier moves in a circle without forming a deposit. But this applies to the first heat exchanger. In the second, water is taken from the pipeline. As practice shows, the quality of the media often leaves much to be desired. For this simple reason, it makes sense to install filters in front of the media that will remove insoluble compounds. If the circuit breaks down, the boiler can operate in room heating mode. This way you won't sit in winter time in a cold apartment or house.
How the DHW (hot water supply) system works
If you switch double-circuit wall-mounted gas heating boilers to summer mode, then only the medium heating system for domestic needs will function. Essentially, the batteries will be cold, and hot water will come out of the tap. The principle of operation here is extremely simple. The three-way valve changes its position and closes the heating line, thereby opening the way to the secondary heat exchanger, where the media is directed. As water passes through the carrier, it heats up and goes straight into the hot water circuit. The process begins with the launch of a relay, the contacts of which close when the media consumption exceeds 2.5 liters. The microprocessor sends a command to ignite the burner, and then gradually opens gas valve. The power increases progressively. Then the device switches to the mode of smooth temperature control. It is worth noting that gas wall-mounted double-circuit heating boilers from all manufacturers are designed so that the burner turns off when the set temperature is exceeded by 5 degrees, and turns on when the medium temperature drops by 1 degree.
Gas double-circuit turbocharged boiler: advantages and disadvantages
The essence of the operation of turbocharged models is that there is an air supply for the gas combustion process, as well as the removal of combustion products using a built-in fan. In this case, there is a pair of small diameter air ducts. The process happens simultaneously. Combustion products are released into the environment, and the oxygen necessary to maintain combustion, on the contrary, is supplied to the boiler. The fans are mounted inside the boiler. But it is worth drawing your attention to the fact that forced removal is suitable for units with a power of no more than 30 kW. As for the advantages, they are obvious; there is no need to build a chimney. There are two pipes leading out onto the street, one of large diameter, the other of small diameter. The first is used to supply oxygen, the second is to remove combustion products. But there are also disadvantages here; the fact is that double-circuit gas heating boilers have more complex design, and it is not always possible to make a hole in the wall. Let's look at another important point.
User manual
It is difficult to give specific recommendations here, due to the fact that each manufacturer has its own recommendations. But there are several general rules that need to be done to normal operation your boiler. Firstly, there is a special filter between the pipeline and the heat exchanger. So, it needs to be cleaned or changed periodically. How often to do this, find out in your passport. Another requirement is to monitor the pressure in the system. In most cases it should not fall below 0.5-0.75 Bar. If the indicator is lower, you need to add water to the system; if it is higher, then vice versa, drain a certain amount of media. There are often two valves, as well as a pressure gauge indicating pressure. If the arrow is in the green zone, then everything is fine. There is one trick that is to reduce the amount of scale in the system. It consists in not raising the temperature of the media above 45 degrees Celsius. When it rises, salts and other elements decompose, which form a dense coating.
Diagram of a double-circuit boiler
Let's talk about how to properly connect the device. Often this is done by professionals, but if you decide to do it yourself, then nothing will work without certain knowledge. Firstly, a double-circuit gas boiler, the operating principle of which we have already examined, must include a mechanical filter at the inlet. It is advisable to first install a shut-off valve on the boiler return. This is done so that there is no need to air the system if the unit breaks down. Afterwards, the boiler is installed directly, then communications are supplied, that is, water supply, gas, and also installed for the removal of combustion products and the supply of oxygen. In any case, the system is started under the control of the gas service. Do not forget that the wall-mounted one must be installed strictly level.
Conclusion
If you are going to install the device yourself, then you will definitely need a dual-circuit circuit gas boiler. Often it makes sense to pay and entrust this matter to professionals. This is due to the fact that you will be dealing with explosive gas, so any leakage can lead to serious consequences. That, in principle, is all on this topic. Now you know how a double-circuit gas boiler works. The operating instructions are required to be read, because you are dealing with serious equipment. Moreover, if you do not read the relevant documentation, you may not know many important points and “fail” the warranty on the device, as a result of which you will have to spend your own money if it breaks down.
It is impossible to imagine a house or apartment without heating. Man has invented many devices for heating homes, but gas double-circuit heating boilers, which have unique consumer properties, are extremely common and occupy up to 75% of the heating equipment market. The market offers boilers of imported and domestic production; the choice of products from different manufacturers is huge. How to choose the most efficient, safe and durable home heating unit? For example, if you choose a double-circuit gas boiler, what is it and why is it better than other appliances?
For comfort in the house, heating alone is not enough, because you also need hot water for household needs, and its supply can be provided by a double-circuit gas boiler for heating, which needs to be selected correctly. This device is quite complex, expensive and is purchased for many years, so gross mistakes when choosing a boiler are unacceptable. The question of how to choose double-circuit gas boilers, which are the best and most reliable, is difficult to answer unequivocally, because many different factors should be taken into account when purchasing.
The modern one is a high-tech product that heats the home and supplies hot water for the hot water circuit. To minimize human intervention in the operation of the heating system, the units are equipped with complex automatic systems.
The power of boilers offered on the market varies, from tens to hundreds of kilowatts, which makes it possible to select a heating unit for a house of any size and number of floors. The price of gas boilers depends on the manufacturer’s brand, power and model of the boiler. The design of most models fits perfectly into the interior of the premises.
Double-circuit boilers at the installation site are divided into two large groups:
- floor-mounted double-circuit units with high power and weight;
- wall-mounted double-circuit gas appliances.
Floor-standing double-circuit boilers
For private houses with a large area and several floors, in specialized stores or online stores you can select and buy a double-circuit floor-standing gas boiler with the estimated power required to heat a particular home. These units have significant weight and size, so a separate room is provided for their installation - a boiler room.
Models are available that are network-dependent and non-volatile. This criterion should be taken into account first of all before buying a heating gas boiler, because the electrical network may be unreliable or completely absent. It should be borne in mind that closed heating systems of complex configuration do not work without, therefore for uninterrupted operation you need to install an uninterruptible power supply (UPS) or gasoline generator. For simple open systems, in which the coolant moves due to gravity, there is no dependence on the electrical network.
Types of floor-standing gas boilers:
Wall-mounted gas double-circuit boilers
Not long ago, Russian consumers had the opportunity to purchase a double-circuit wall-mounted heating boiler. Products of this type have earned consumer recognition and in a short time have become popular for autonomous heating. extremely compact, they can fit into any interior or be built into a closet, making it invisible. The power of mounted boilers, depending on the model, ranges from 13 to 55 kW.
Wall-mounted models of gas boilers, despite their small size, contain the following components and devices:
When choosing a wall-mounted double-circuit boiler, you need to try to take into account many characteristics for the optimal choice of unit model that will provide heating for the house and hot water.
You should not choose a double-circuit wall-mounted gas heating boiler with a power significantly exceeding the calculated value.
Typically, 20% is added to the design power, and for areas with extremely low temperatures in winter, up to 50%.
The main advantages of double-circuit wall-mounted boilers:
Leaders in the heating equipment market
To understand development trends and demand for heating equipment, leading company specialists do analytical reviews, which present a rating of gas double-circuit boilers, those that had the greatest demand and popularity. Reviews explain in detail why on the list the best products included the most popular models of heating equipment.
Recently, there has been a stable trend - the demand and sale of double-circuit gas boilers has increased significantly, especially the new generation of boilers. Many companies offer completely new innovative solutions which will allow us to create even more advanced products.
The most popular gas boilers in Russia
The popular Ross gas boiler is produced at the Kharkov plant in the form of wall-mounted, floor-standing and parapet models. They differ in power and quantity additional functions. The popularity of Ross boilers is due to affordable price And high quality units. You can order a boiler at the factory without intermediaries, which will significantly reduce costs.
Wall-mounted double-circuit gas boiler Avangard with a rated power of 24 kW. The boiler meets European standards in its technical characteristics and has all the necessary certificates. The device is non-volatile with a cast iron heat exchanger and comes with a 10-year manufacturer’s warranty. The unit is equipped with Italian non-volatile automatic equipment. All components from leading European companies.
The Vulcan wall-mounted gas boiler is one of the ten best-selling units in Europe. Models with power from 7 to 20 kW are available. All models of Vulcan boilers are equipped with imported automatic equipment, they are relatively inexpensive and are designed for heating small houses and apartments.
The popular gas boiler Thermotechnik is a standard heating device of simple design. Its technical data is lower than that of advanced foreign models. But the fact that its price is several times lower than that of imported products, it works stably and reliably in operation, and determined its extraordinary popularity in Russia.
From all of the above, we can assume that the popularity of wall-mounted double-circuit boilers will increase.
Many manufacturers are working to improve the performance, efficiency, safety and reliability of their products.
Many companies that produce heating equipment have the main part of their range of wall-mounted double-circuit boilers designed for organizing DHW systems and heating of houses. It seems that this trend will continue in the foreseeable future.
Double-circuit boilers
Korean heating boilers
Don't depend on quality central heating and hot water supply is quite simple. All you have to do is install the boiler at home and independently regulate the temperature and duration heating season. And if in apartment buildings installation of autonomous heating for safety reasons may be prohibited, depending on the number of storeys, then in one-story cottages and private houses, this The best decision heating and hot water problems.
The main thing in an autonomous heating system is, of course, the boiler. There are several types of them. As fuel they use both traditional fuel - gas and coal, and alternative fuel - wood chips and briquettes. Single- and double-circuit boilers are most preferable for installation in a cottage.
Single-circuit heating boilers
A single-circuit boiler primarily works to heat rooms and create comfortable temperature. As the name suggests, one coolant circuit passes through the boiler. If desired, a heat exchanger can be connected to the heat source to heat the water. The operating principle of a single-circuit boiler is extremely simple. Fuel enters the firebox, which heats the coolant circulating through the pipelines inside the boiler. The coolant circulates through the heating circuit either due to the temperature difference or using a circulation pump. For high-quality heating of premises, water circulation in the circuit must be constant.single-circuit boiler with a connected boiler, hot water comes from the boiler
As for connecting an additional heating circuit, which is located outside the boiler, it will not be difficult to connect it. But is there any benefit to this? The thing is that connecting a boiler to heat water will make the operation of the boiler unstable. This is due to the fact that the amount of heat required to heat water is not constant throughout the day. Maximum water withdrawal occurs in the morning and evening hours. The boiler needs to be rebuilt and fed to the burner large quantity fuel. After cessation of consumption, the boiler remains to work only for the heating system. Such operation of a single-circuit boiler will not be economical and will lead to excessive fuel consumption.
Advantages of a single-circuit boiler:
- Such boilers are equipped with an automatic safety system. It is this that allows you to select the optimal operating mode of the equipment and fuel consumption.
- Based on single-circuit boilers, you can create various systems heating with different wiring in rooms. Right choice allows you to increase the service life of the boiler, as well as improve it specifications.
- New models of single-circuit boilers have built-in weather control sensors. This means that the outside air temperature regulates the fuel supply to the burner, and consequently reduces or increases the temperature in the supply pipe.
- The simplicity of the design makes single-circuit boiler models very reliable and easy to control and regulate.
Double-circuit boilers
If living without hot water is not part of your plans, then you should think about purchasing a double-circuit boiler. It differs from a single-circuit one in that its design includes an additional heat exchanger for heating water. Depending on the power of the boiler, it is possible to organize heating of water and supplying it to two water points at the same time. To minimize the cooling of water on the way to the points of analysis, it is advisable to place the boiler closer to them.There are two types of double-circuit boilers: with one or two heat exchangers. In the first case, coolant passes through the heat exchanger for heating needs. If it is necessary to heat cold water, the supply of coolant to the heat exchanger is shut off, and the supply of cold water for heating is opened. This is not very convenient, especially in the cold season.
Boilers with two heat exchangers are more popular. They work independently of each other. In one heat exchanger, heating water is heated, and in the other, cold water is heated for the needs of hot water supply. Modern double-circuit boilers are equipped with steel heaters that heat water in a short period of time.
double-circuit boiler, hot water comes from the boiler
Advantages of a double-circuit boiler:
- Purchasing such a boiler will cost less than a set consisting of a single-circuit boiler and a boiler.
- The boiler is quite compact.
- Water does not fill into storage tank, and exactly the amount of water that is needed at the moment is heated. This reduces heat loss due to cooling.
How to choose a boiler of appropriate power
If the choice in favor of a single- or double-circuit boiler has already been made, then it is necessary to select a boiler of appropriate performance. In order to ensure that the air temperature in the rooms is comfortable and the hot water temperature is about 50 degrees Celsius, you can make a simple calculation of the power of the installed boiler. To do this, the area of all heated rooms is summed up and divided by 10. This gives an approximate heating load. By increasing it by about 15-20%, we have the total power of the boiler, taking into account the hot water supply. However, as professionals advise, it is worth purchasing a boiler with a slightly higher productivity than that obtained by calculation. The thing is that over time, the performance of the equipment decreases, the heat transfer from the fuel to the coolant decreases, due to contamination of the heating surfaces. In addition, when selecting equipment, one should take into account the amount of heat loss from pipelines and possible voltage drops.Boiler manufacturers - which model is better?
It’s easy to get confused in the variety of brands offering their products. How to choose a boiler and not make a mistake with the choice. Currently, the heat and power products market mainly offers equipment from several countries. These are Germany, Italy, Korea and Russia. All boilers have some differences associated with the technical characteristics of their work and also significant differences in cost.German heating boilers.
Bosh boilers have proven themselves for a long time with the best side. Their design is constantly being improved. The boiler is equipped with automation and safety devices that regulate the fuel supply to the burner and are activated in the event of an emergency. To improve heat removal during boiler operation, all heat exchangers are made of copper, which are coated special staff to prevent the corrosion process. The estimated service life of such a boiler is 20 years.
Another one German company, which produces high-class boilers, is Viessmann company. They specialize in the production of both single- and double-circuit boilers. Their equipment is characterized by excellent assembly and technical characteristics. According to the stated characteristics, the efficiency of such boilers reaches 93%. In addition, the company's engineers have developed a unique chimney design that prevents condensation flue gases in the pipe and, as a result, their freezing.
Italian heating boilers
Boilers Italian companies also different good quality assemblies. One of the most famous Italian brands, Beretta, produces high-power boilers. In the model range you can select heating equipment with a power of up to 24 kW. These can be single-circuit, double-circuit boilers, boilers with a built-in or free-standing boiler. A distinctive feature of Beretta equipment is that it can operate even in very low temperatures outside air.Baxi has been on the heating equipment market for several years. During this time, specialists are constantly developing and implementing new solutions. The fifth generation boilers have an atmospheric burner, which operates almost silently. Baxi equipment is represented by a wide range of models with power from 10 to 80 kW. The boilers are relatively small in size and have a high efficiency - up to 90%.
Korean heating boilers
Korean-made boilers combine modern technologies and reliability. They are equipped with protection systems against voltage surges, increased pressure and temperature in the collectors. The boiler also has a built-in natural gas leak detector. If it is detected, the boiler automation will shut off the gas supply to the burner device.Navien is a leading manufacturer of boilers. It produces boilers operating on in various forms fuel with different numbers of circuits. The equipment is equipped with burner devices that operate even at low natural gas pressure. In addition, a voltage stabilizer is built into the boiler, which protects the system from overloads.
The Olympia company specializes in the production of double-circuit boilers equipped with a weather control system. The power range of models of this brand is quite wide, which allows you to choose a boiler for a room of any size. All boiler models are equipped the latest system automation systems that allow you to smoothly regulate the operation of equipment and even protect the system from freezing.
Domestic boilers.
Danko boiler equipment regularly receives good feedback from users and experts. From model range, presented by the company in the range from 7 to 15 kW, you can easily select a boiler for heating a small country house or apartment, subject to permission. The boiler unit is equipped with a gas filter, a steel heat exchanger and an economical micro-torch burner.
Another company that produces competitive boiler equipment is OJSC Borinskoye ISHMA BSK. Distinctive feature The advantage of these boilers is that they are produced with a built-in circulation pump. In this case, the boiler can operate both with and without a working pump. This is very convenient when there are frequent power outages.
What to look for when buying a boiler
- Burner. The economical operation of the boiler depends on it. It is important that the burner design facilitates high-quality mixing of gas and air, and therefore complete combustion of the fuel without chemical underburning. The most economical are automatic burners with a built-in fan. Before being fed into the furnace, the gas is mixed with air and then fed into the boiler. The disadvantage of such a burner is the additional noise created by the fan.
- Heat exchanger. The quality of heat transfer from 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 taken into account that under the influence of high temperatures and corrosion, its elements often fail. The more famous the boiler brand, the easier it will be to select a replacement part.
- Electronics and automation. The boiler, equipped with sensors and allowing operation to be adjusted by just pressing a few buttons, is simple and easy to use. But it is worth considering that if there is a power outage, the boiler protection will work and the fuel supply to it will stop. You should choose equipment that has the ability to manually regulate its operation in any case.
It is important to be careful when choosing a boiler. After all, it will last for decades and will create a feeling of comfort and coziness on winter evenings.
Heating a house or apartment is a very important component. Our winters are cold, and therefore we need to approach the heating system as responsibly as possible. Of course, those who have central heating have nothing to worry about (if only what kind of radiators are installed), but those who have heating through their own boiler (now they also have it in apartments) need to think about which option to choose! And now so-called double-circuit boilers have appeared! Let’s talk about what it is today...
A little definition
IN modern world boilers have stepped far forward, more economical options have appeared with electronic system controls that heat not only the heating system, but also combustible water - These are the options that are called two-contour, one boiler circuit is used for heating (heating), the other boiler circuit is used for heating hot water.
Difference between double-circuit boilers
It should be noted that the first heating circuit is the same on almost all boilers; it is a flow-through type. But the second circuit, which works for hot water, can differ in two types:
1) Boiler with built-in boiler – next to the heating circuit, such a boiler has a built-in boiler for storing hot water. That is, the second circuit works as usual storage water heater, however, water heating occurs much faster than in electric boilers. Such boilers are the most economical in gas consumption, because heating the boiler does not require large gas consumption, and the water that accumulates there is heated by a less intense flame. As a rule, such boilers are limited to boilers of 130 - 150 liters (this is the maximum), if this is not enough for you, then you can look towards the second type of boiler.
2) Boiler without built-in boiler – such a boiler does not have a built-in boiler, the second circuit is the same as the first flow-through type (something similar to a gas water heater), that is, there is no boiler, but there is a second flow-through circuit. The disadvantages of such a boiler are significantly higher gas consumption, and also not such a strong pressure of hot water.
Pros and cons of double-circuit boilers
Pros:
— Wall-mounted options save a lot of space
— Technologically advanced, you don’t need to light the flame, everything will be done by electronics
— The protection system, if there is no electricity or gas, the boiler will not turn on, thereby protecting against gas leakage.
— Replaces a boiler + gas water heater
— Saving money on installing two systems
— You can turn off any circuit at your discretion, for example, heating is not needed in the summer, it can be turned off
Minuses:
— Many double-circuit boilers have low hot water output, which forces them to use low pressure
— Heating and heating are not proportional, the power of the first heating circuit is almost always much greater
In any case, double-circuit boilers are modern solution for an apartment - a house, several of my friends have such options - they are very happy.
The desire of many apartment owners to achieve maximum autonomy and independence from city utilities is quite understandable. One of the main issues in this regard is creating your own heating system. This allows you to independently determine the start and end dates of your “local heating season”, setting the desired temperature in the premises at any time of the year, without freezing if the cold in the fall came too early or the arrival of spring was too long, and without suffering from the heat if the situation develops in a diametrically opposite way. And from the point of view of payment for services, it turns out to be much more profitable. Therefore, the installation of individual heating boilers is among landlordV an increasingly popular trend.
Well, if the owners plan to create their own autonomous heating system, then it would be quite reasonable, in parallel with this, to immediately resolve the issue of independent hot water supply. It is no secret that almost everywhere with the supply of hot water throughout the year various “surprises” occur, and in addition, prices for utilities tend to constantly increase. Thus? own heating and hot water supply system means not only “technical”, but also, to a certain extent, financial independence. In addition, an important aspect is.
Of course, the limited space conditions of apartments in multi-storey buildings limit the owners in the choice of boiler equipment. However, there is a way out - this is a double-circuit wall-mounted gas boiler, how to choose which will be discussed in this publication.
Operating principle of double-circuit boilers
Today, in cities, network gas remains the most inexpensive source of energy. If multi-storey building connected to the gas main, then certainly, despite certain administrative and technological difficulties in installing the appropriate equipment, such a heating and hot water supply system will become the most profitable. Paying bills only for actual spending "blue fuel", the owners receive in return both independent heating and an uninterrupted supply of hot water for household needs. Moreover both the timing of switching on and the heating temperature - it all depends on the desires of the apartment owners.
With a certain simplification, the principle of connecting a double-circuit boiler can be schematically depicted as follows:
The boiler itself (item 1) is placed on the wall in the most convenient place, where there will be a connection to the gas main (item 2) and to the combustion product removal system.
Hot water circuit. A cold water supply pipe is connected to the boiler (item 3, blue arrows). Heated water is distributed (pos. 4, red arrows) according to a collector or corner circuit to points of consumption - in the bathtub (pos. 5), shower stall (pos. 6), kitchen sink (pos. 7), etc.
The heating circuit is closed. Circulation pump (most often it is a structural unit of the boiler itself) ensures the movement of the coolant through the supply pipes (item 8) and “return” (item 9). Depending on the specific features of the heating system, conventional radiators (pos. 10), water heated floors (pos. 11), and convectors of one type or another (pos. 12) can be connected to the heating circuit. If desired, you can also install other devices here, for example, heated towel rails (item 13).
Thus, five pipes fit and connect to the wall-mounted double-circuit boiler:
- Gas main.
- Supply of the heating circuit with further distribution to priors or heat exchange systems.
- “Return” of the heating circuit.
- Cold water inlet
- The outlet of the heated water supply system for domestic needs with subsequent distribution to water intake points.
Inside the boiler itself, both circuits - heating and hot water supply - do not directly intersect, which makes it possible, if desired or necessary, to use a special coolant in the heating circuit.
By and large, this is the fundamental difference with single-circuit boilers, many of which have the ability to connect to a hot water supply system, but only through a boiler indirect heating.
Look at the diagram. Everything seems to be the same, but the points of consumption of hot domestic water are connected to an indirect heating boiler. And he, in turn, connects to the dedicated the boiler circuit along which the same coolant circulates as in the heating system.
Even if such a boiler has four water pipes at the outlet - two for heating circuits, and two for an indirect heating boiler, it will still not be considered double-circuit. It’s just that its internal design provides for rational redistribution of coolant flows with the necessary automation of this process. But the heat exchanger is used alone, and the composition of the liquid circulating in both circuits is no different.
A system using an indirect heating boiler has a number of significant advantages. In particular, it is possible to organize local closed recirculation of hot water supply - at any time, whenever the tap is opened, hot water at the set temperature will immediately flow out of it.
But there are also several negative aspects. Firstly, the cost of such a kit is always quite high. And secondly, and for small apartments, perhaps the most important thing, installing a boiler and boiler will require a considerable area, which is not always possible.
It is in such conditions that a double-circuit wall-mounted boiler will help out. Its main advantages:
- Compactness - it does not take up much space, and at the same time, as a rule, does not disharmonize with the kitchen interior.
- Two problems are solved at once - heating the apartment and meeting the needs for hot water. The owners largely get rid of the “whims” of public utilities.
- Similar boilers correct installation and a well-thought-out, balanced autonomous heating system are very economical - this will certainly be immediately noticeable in the amount of monthly utility costs.
- The total cost of purchasing and installing a double-circuit boiler will be significantly lower than for a single-circuit boiler with an indirect heating boiler.
However, double-circuit boilers are not without significant disadvantages:
- These devices operate in only one mode at a time. For example, if it is necessary to heat domestic water, the boiler switches completely to water supply, temporarily turning off the heating circuit.
- As in the case of a gas water heater, there is a certain “inertia” - when you open the tap, you will have to wait until the cold water remaining in the pipes flows out and until the boiler “accelerates” to the desired heating temperature.
- Many double-circuit boilers are very limited in the volume of heating running water. So, taking a shower and washing dishes at the same time will either not always be possible or uncomfortable - when you close one tap, a temperature jump will inevitably occur in the other. True, many modern devices are equipped with an internal boiler, which eliminates this disadvantage.
- If in a single-circuit boiler purity of the coolant can be achieved, then in a double-circuit boiler Besides tap water is heated, which is not always and not always of the same quality. This gives a certain risk of overgrowing heat exchanger tubes, which You will have to either clean it regularly or replace it with new ones.
Which double-circuit wall-mounted boiler should I choose?
The boiler connection diagram shown above is very arbitrary, and in no way covers the variety of these devices. So in order to correctly determine the right model, it is necessary to take a closer look at the main selection criteria.
Boiler power and performance
- The boiler must fully cope with its main task - to ensure operation autonomous system heating. This means that one of the basic selection criteria is its thermal power.
Experts calculate the total amount of heat required by an apartment or house based on many factors - from the area and volume of the premises to the material of the walls, the degree of insulation of the building and the climate zone of residence. To independently determine the required boiler power, you can, with acceptable simplification, proceed from the standard of 10 m² of area of sealed premises per 1 kW. this rule will be valid with an average ceiling height of up to 2.5 - 3 m, and if the rules of proper thermal insulation are still followed in the house (apartment).
It is clear that the heating device should not operate at the peak of its capabilities, so it is better to provide a certain reserve, especially in the case where the insulation of a high-rise building still does not inspire complete confidence. Plus, the boiler needs additional power to heat water. In a word, it would not be a mistake to add another 30 ÷ 35% to the obtained value.
Most modern double-circuit boilers have a fairly wide power range. Technical documentation usually indicates its minimum and maximum values. For example, useful thermal power: 9.3 ÷ 14 kW.
- The second component of the problem is the performance of the device for heating water for domestic needs. If there is no boiler, then heating will be carried out according to a flow-through circuit, and the selection parameter depends on the number of water points that can operate simultaneously. It is clear that the more liters per minute the boiler can heat, the better.
Typically, the technical documentation of double-circuit boilers indicates several performance values, with different indicators of the temperature difference at the inlet and outlet. Usually they operate with the values Δt° = 25 and 35 degrees. This is not the temperature of the water at the outlet, but rather the increase in its value compared to the input. For example, in summer time in the water supply the water can be 15° WITH, and at Δt° = 25° 40° will flow into the taps, which is quite enough for taking a shower.
In principle, a productivity of about 10 ÷ 11 l/min at Δt° = is considered to be very good indicators 25 ° WITH, and 7 ÷ 8 l/min at Δt° = 35 °C.
All these considered characteristics will be valid only if the gas pressure in the main and water in the water supply correspond to the parameters specified by the manufacturer. You should also pay close attention to this.
Type and number of heat exchangers
According to the principle of heating water for domestic hot water, boilers can vary significantly. So, there are two main types of such devices - with a secondary heat exchanger and with a bithermic one. Each type has its own characteristics.
Main boiler heat exchanger, which is responsible for the most energy-intensive function, heating, and is always located above the gas burners. And water heating can take place in the same place, or with heat transfer from the heated coolant through an additional device - a secondary heat exchanger.
Double-circuit boilers with a secondary heat exchanger
The primary heat exchanger itself is metal structure– a curved pipe, the turns of which are united by plate ribs to increase the heat exchange area from the hot combustion products to the circulating coolant. IN this option The boiler of such a heat exchanger has two pipes - inlet and outlet.
Heating of water for domestic needs is carried out in secondary heat exchanger, which is located below the combustion chamber and is in no way in contact with the burner flame. Typically this element has a compact plate design.
Secondary heat exchanger - more compact, plate type
There are already four pipes here, and inside there are two circuits for counter-flow of liquid. In one way, the heated coolant circulates, giving off heat, in the second, tap water receives it.
The operating principle of such a boiler is shown in more detail in the diagrams.
- The boiler is operating in heating mode.
Above gas burner(position 1) the primary heat exchanger is located (position 3). The combustion of gas supplied through the line (yellow arrow) leads to heating of the coolant in the circuit. The circulation pump (item 5) ensures the movement of liquid through the heating pipes. The three-way valve with a servo drive (item 7) is in a position in which the valves open the flow from the return of the heating circuit and at the same time close the entrance to the secondary heat exchanger.
Prices for Baxi gas boilers
gas boiler Baxi
As a result, circulation occurs “in a large circle”, through heating collectors and installed heating devices.
The diagram additionally shows the built-in expansion tank (item 8) and the safety group - safety valve and automatic air vent(pos. 9).
- What happens when you open a hot water tap?
Water flow begins through the pipes of the DHW circuit. This causes the flow sensor turbine (position 6) to rotate. The signal from the sensor enters the automation unit, where a control pulse is generated to the three-way valve (item 7). The valve moves to the position in which the valve closes the inlet from return lines heating, but opens the entrance to the secondary heat exchanger. In this case, the pump does not turn off, ensuring the circulation of the heated coolant in a “small circle”.
During use hot water the circulation of coolant through the heating circuit is suspended.
In the event that this happens during a period when the heating is completely turned off, when the hot water tap is turned on, the flow sensor will transmit a signal to the control unit, which will start the circulation pump, open the gas valve and trigger the electronic igniter (item 2). The gas heaters (item 3) are ignited, and the circulation of the coolant begins through the secondary heat exchanger, transferring thermal energy to the water.
Advantages of boilers with a secondary heat exchanger:
- Double heat exchange eliminates the possibility of getting burned by overheated water. Under any circumstances, if the primary circuit temperature can reach 80° WITH, then in the secondary it will not rise above 60.
- For the same reason, and also because heating occurs exclusively during circulation in both circuits at the same time, the build-up of scale in the secondary heat exchanger is much less than in boilers with a bithermal heat exchanger.
- The primary heat exchanger tubes can be made thicker and are less at risk of clogging or fouling.
- Even a clogged primary heat exchanger can be washed and cleaned.
- This boiler is more repairable– each unit can be removed, cleaned or even replaced. Cost of each heat exchanger separately- not so high.
Disadvantages of boilers with secondary heat exchange in the DHW circuit
- The price of such equipment is higher than with a bithermal heat exchanger.
- The presence of an additional electromechanical valve (three-way valve) is an extra vulnerable point for breakdown.
Video: a short “lecture” on the construction of a wall-mounted double-circuit boiler
Boilers with bithermal heat exchanger
In these types of boilers, both heat exchange circuits are combined into one structural unit.
Bithermal heat exchanger - outside view...
Externally, the heat exchanger seems to be similar to the primary one, which was already mentioned above. But there are only four pipes - a pair each for heating and hot water supply.
... and he is in the cross-section
If you look at a cross-section of such a heat exchanger, you can see that the tubes have a cellular structure. Hot water circulation circulates through the central channel. External channels (in this case, four) are intended for circulation of the heating system coolant.
If only the heating is turned on, the circulation pump ensures the movement of the coolant, and the water in the central channel is motionless.
When you open the hot tap on the mixer, under the influence of the water supply pressure, water begins to move through the inlet pipe (item 1) towards the outlet pipe (item 2). The flow sensor through the control unit turns off the circulation pump of the heating system, and the movement of the coolant stops. The heat from the burners is taken over by the heated water. When the tap is turned off, the pump resumes operation, and the heating system becomes the main one.
Advantages of such a scheme:
- One heat exchanger takes much less space. In addition, there is no three-way valve with a servo drive or additional piping. This makes the entire structure of the double-circuit boiler much lighter and more compact.
- Although a bithermal heat exchanger is sufficient complex from the point of view of the manufacturing technology of the part, its cost is still lower than two separate heat exchangers. This also affects the price of the boiler.
The disadvantages are very significant:
- In any mode, in one of the heat exchanger circuits the liquid is stationary, but is subject to heating. This leads to fairly rapid scale formation and overgrowing of the channels.
- The relatively narrow clearance of all channels also leads to the same consequences. Overgrowth of at least one of them leads to a decrease in boiler performance and the appearance of unpleasant noises.
- While the hot water supply circuit is closed, the water continues to heat up and reaches the same temperatures as the heating fluid. When you open a tap, very hot water may initially flow, which can scald your skin. To minimize such a risk, they try to limit the overall heating temperature using hardware and software methods (not higher than 70 ÷ 75 ° WITH, although this is already too much). But such a reduction simultaneously entails a reduction in the possible thermal output of the boiler for the heating system.
- A bithermal heat exchanger is more difficult to manufacture, and the presence of a large number of joints greatly increases the likelihood of leaks. Cleaning such a structure from scale is much more difficult. Well, if a leak occurs (especially between the external and internal circuits), such a heat exchanger is practically beyond repair and requires mandatory replacement. But its cost is much higher than both primary and secondary in other types of boilers.
Thus, in terms of these positions, a boiler with secondary heat exchange in the hot water supply circuit still looks preferable.
Prices for Vaillant gas boilers
Vaillant gas boiler
There is another innovative type of double-circuit boilers - with a condensation-type primary heat exchanger. They are designed with an eye to a fairly serious effect of saving gas consumption at the same or even higher thermal power levels.
The fact is that one of the combustion products of natural gas is always water vapor. In ordinary boilers it is simply released into the atmosphere, and yet it thermal energy(temperature reaches 110 – 140 ° WITH) can additionally be used to heat the coolant.
A special heat exchanger device ensures steam condensation with heat release. Studies have shown that steam potentially stores up to 11% of the total heat generated by the boiler, and if their unreasonable losses are returned to heat exchange, then gas savings over the season can reach 30% of the usual consumption level.
Of course, such energy-saving boilers are the future, and in many countries they have taken leading positions in popularity. The only thing that still holds them back from widespread use in our area is the very high price.
Type of combustion products exhaust system
Boilers are divided into two large subgroups - with an open combustion chamber and with a closed one. Accordingly, they are spilled into systems for supplying the air necessary for gas combustion and for removing combustion products into the atmosphere.
Chimney boilers with an open combustion chamber
An open combustion chamber assumes that air flows to the burners naturally, from the room in which the boiler is located. Combustion products, also naturally rising up, are redirected to the pipe to which the chimney pipe is connected. In a word, the effect of natural draft is used, based on the difference in the density of cold and heated gases.
The advantages of such a boiler:
- The operation does not require a special fan. This means the absence of noise and lower power consumption of the boiler.
- The contraction does not have complex air injection and control elements (pneumatic relays), therefore, the overall reliability of the device is higher.
- A chimney assembled in accordance with all the rules solves the problem of condensation formation.
- Chimney boilers are cheaper than turbocharged boilers.
Flaws:
- Air enters the combustion chamber directly from the room. This means that it is necessary to think through the issues of constant supply ventilation. And this very often leads to excessive heat loss in the premises and the appearance of drafts.
- There are special, fairly strict rules for the design and installation of a chimney. This often leads to large-scale repair and construction work and serious expenses - otherwise you will not be able to obtain permission to install the boiler.
- Installing a chimney is not possible in principle in all buildings.
Flueless boilers with a closed combustion chamber.
Such boilers are often called turbocharged. The air for them is supplied from the street forcibly, using a special fan-turbine; accordingly, combustion products are also thrown out into the street by the created pressure.
The chamber itself is completely closed, and exhaust gases cannot enter the room.
The supply of air and the emission of combustion products can be carried out through two separate pipes, but the vast majority of modern boilers of this type provide for the installation of a coaxial system - a “pipe in a pipe”, which is discharged through the wall to the outside.
Inside the outer pipe, usually 100 mm in diameter, a second pipe with a diameter of 60 mm is located coaxially. Through the space between the outer wall and the inner pipe, air is forcedly drawn in from the street. The internal channel serves for the exit of combustion products.
Advantages of such a system:
- There are practically no significant restrictions on its installation.
- There is no need to provide fresh ventilation in the room.
- The cost of such boilers is slightly higher, but it is fully justified by the absence of large-scale work on the design and construction of the chimney.
The disadvantages are the following:
- A significant temperature difference in the outer and inner pipes is accompanied by the formation of condensation. In severe frosts, this can lead to icing, impairing the permeability of the chimney and, accordingly, insufficient vacuum in the chamber for the automation to operate.
- Mandatory elements of the system are a pneumatic relay, a fan and a fan switch relay. All of them have a certain resource, and failure of any of them leads to failure of the boiler.
- The fan creates noise when operating. In addition, this is an additional energy consumption.
Conclusion: a boiler with an open combustion chamber and a conventional chimney looks more reliable in operation. But turbocharged boilers are easier to install and have no special restrictions on the installation location.
You might be interested in information on how to choose
Controls, automation, protection levels
The boiler must be fairly easy to use, have clear controls, be equipped with the necessary functions to optimize operation and several degrees of protection against emergency circumstances.
Presenters manufacturing companies They are constantly improving their models, thereby creating competition between brands, so new developments are constantly appearing. Thus, modern boilers can be equipped with the following options:
- Flame modulation in heating and water heating modes. The flame level is electronically regulated, ensuring smooth starts, which is especially important for models with instantaneous heating of DHW water. The automation independently selects the height of the flames depending on the set temperature and the specific current water flow.
In some models, the last 5 degrees to the set heating temperature of the heating system are gained at a reduced combustion intensity. This allows you to make the operation of the device smoother, reduce the number of starts, and therefore increase the service life of the equipment.
- Similar goals are pursued by the smooth electronic ignition system, when after the minimum flame appears on the burners, it gradually grows to given intensity burning for 30 - 40 seconds.
When the boiler operates as a water heater, this option does not apply - what is important here, on the contrary, is the speed of heating the water to a given level.
- Weather-sensitive boiler automation. This is an innovation, when installing an external street sensor, allows the equipment to monitor the level of external temperature and make adjustments to maintain an optimal microclimate in the apartment.
More advanced equipment of this type also has an automatic self-adaptation function. Electronics not only compares graphs of changes in external and internal temperatures, but also conducts an analysis, making adjustments to the operation of the boiler, which leads to maximum comfort and significant gas savings.
- Pump post-circulation. A useful feature that, when installed room thermostat, allows you to significantly reduce energy consumption. Once the required heating temperature has been reached in the heating system, the boiler turns off and the pump continues to operate for another three minutes. When it is necessary to resume operation, both the boiler and the pump are started simultaneously.
- Naturally, all modern boilers with electronically controlled allow you to accurately set the temperature in both the heating circuit and the DHW. In addition, some models provide two switchable ranges in heating mode - for conventional radiators and for heated floors.
- The electronics allow programming of the boiler operation for a certain period of time, with the programs being stored in memory for reuse.
- Any gas equipment has several degrees of protection - in case of insufficient traction, when the heating pad goes out, in the absence or insufficient water pressure in the circuits, etc. In addition, modern models are equipped with other safety functions. So, if the temperature in the circuits drops to +5 degrees, the boiler will start on its own to bring the heating level of the coolant and water to a safe value, in order to avoid freezing. In addition, some control systems also monitor the condition of the boiler elements. If the device has not been used for more than a day, the processor will will turn on pump or switch the position of the three-way valve back and forth. This allows you to avoid blocking or “sticking” of these units and extends their service life.
Control panels can have push-button, touch or electromechanical control, and are equipped with dial or digital indicators of temperature and pressure in the system.
Prices for popular gas boilers
Dimensions, “appearance”, manufacturing company
A mandatory evaluation criterion should be the dimensions of the boiler - they must correspond to the dimensions of the place where it is planned to be installed. This takes into account both the location of the gas main and the possibility of connecting to a chimney or installing a coaxial system. There are certain restrictions in these matters, for example, on the length of the coaxial pipe - this must be clarified in the product passport.
You might be interested in information on how to choose
Perhaps, if the installation area allows, it makes sense to purchase a boiler with a built-in boiler - its dimensions are certainly larger, but its ease of use is incomparably higher - this has already been mentioned.
For many owners important criterion The choice is the design of the boiler. It is difficult to give advice here - the main thing is that the device does not spoil the interior. Most of the boilers have a matte white finish, which fits perfectly into any style.
No matter how much you like a particular model on sale, you should always give preference to reputable brands. Leading manufacturing companies provide a solid guarantee for their equipment, and since the boiler can be considered an expensive purchase, this fact is very important.
Very popular modern model"Baxi - Luna3"
Deserved authority and " untarnished reputation» used by European companies “Viessmann”, “Beretta”, “Baxi”, “Vaillant”, “Bosch”,. Protherm, Buderus, Ariston and other companies have proven themselves well. You can completely trust the products of Korean companies “Navien”, “Daewoo”, “Celtic”, “Kiturami” - in terms of equipment with modern electronics, they are sometimes superior to Europeans.
Video: wall-mounted double-circuit gas boilers Daewoo
You should be careful with Chinese technology, despite its relatively low price. Well, a brand “unknown to science” should be discarded immediately, no matter how attractive the model may seem.
When choosing between manufacturers, you should check whether there are any in the region service centers, how difficult it will be to send equipment for maintenance or replacement due to a complaint. Probably, you should not purchase a boiler from even the most popular manufacturer, if in a given area it is “exotic”, and the search for any trifling detail will be difficult.
You might be interested in information about what types of
So, in order to choose a truly high-quality wall-mounted double-circuit boiler that is fully suitable in all respects, you should evaluate many criteria, understand the device, carefully study the technical documentation for the model you like, and compare its technical characteristics with the existing conditions of the planned operation. Don't go for the cheap ones
