Double-circuit gas boiler: operating principle, instruction and diagram

Today, two-circuit boilers are the most in demand on the market. This is due to a number of factors. The most important of them is that a device having two circuits performs several functions. Let's take a closer look at what a two-circuit gas boiler is. The principle of operation of the device, as well as the connection diagram and the instruction manual, will also be mentioned. This article is suitable for those who want to better understand this issue.

Some general information

The two-circuit gas boiler, the principle of operation of which we now consider, can cope immediately with two tasks: firstly, heating and maintaining the set water temperature for the heating system; and secondly, heating the carrier for use for economic purposes. Thus, at home not only heat, but also there is hot water. This is an essential difference between a double-circuit boiler and any other one. One can draw a simple conclusion that the design has two high-performance heat exchangers, each of which performs its function. In addition, a dual-circuit gas boiler can be of different capacities. Today the market has models from 12 to 35 kW. This is quite enough to heat a large room 350-400 square meters. The performance of most models ranges from 8-12 liters per minute.

On the advantages of double-circuit boilers

It is safe to say that the advantages of these units have much more than disadvantages. Now we will consider all the pluses. Firstly, it is a significant saving of gas. This was achieved through the use of modern heat exchangers. By the way, the hydraulic system made it possible to make the operation of the units completely silent, so a dual-circuit gas boiler can be installed in any convenient place. Dimensions in most cases allow for installation without any problems. If the floor variant is not suitable, it is always possible to install the device on the wall, which is especially important for small apartments, where each square meter is important. The operation of the dual-circuit boiler is completely autonomous, which is facilitated by the corresponding equipment (pump, expansion tank, computer and safety system).

A little about the minuses

Nothing lasts forever, nor is it perfect. A two-circuit boiler has several drawbacks. First, one can not help but note the noticeable loss of water at the initial stage. Consider a specific example. Here you turned on the hot water, automatically earned an additional coolant. For hot water to go, you need to wait about 30-40 seconds, depending on the brand of the boiler. Everything that comes with the tap before this time is called loss. It can be said with great certainty that this is not such a big drawback. If it is necessary to heat the medium for household purposes, then the gas dual-circuit boiler does this in a flow-through mode without the possibility of accumulation. Let's go further and talk about how the unit works.

Two-circuit gas boiler: the 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 it is necessary to heat the room, the principle of operation is as follows: the carrier, in our case water, enters the heat exchanger, which heats up to a certain temperature. Today the range fluctuates around 35-85 degrees Celsius. The thermostat starts the heating mode automatically. This is done when the temperature in the system falls below the norm. As a result, the circulation pump starts working and supplies water from the heat exchanger (preheated) to the system. The system pressure 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 to the desired temperature.

The principle of the boiler: Part 2

But this does not end there. After turning on the boiler starts to work on increasing. First, at the minimum power, and eventually reaches its maximum. When the boiler wall-mounted gas dual-circuit heating at some stage of the carrier to the specified temperature, the unit goes into the modulation mode. If, on the first power-up, the power exceeds the permissible value, the microprocessor sends a signal to turn off the burner. Re-activation is carried out in three minutes. The combustion chamber is metallic and has a special heat-resistant winding. Above it is a heat exchanger, below which there is a burner. The latter is ignited exactly at the moment when the temperature of the carrier in the system falls and it is necessary to heat the water. Together with it, a circulation pump is also activated, designed to drive water through a closed system. When the specified temperature is reached, the gas wall-mounted two-circuit boiler enters the standby mode. In some models, the burner burns, but at a minimum, in others it stinks and lights up when the gas is supplied.

A little more about the features of work

To prevent the carrier from entering the secondary circuit, a three-way valve is used. Thus, it was possible to supply the heated water from the boiler to the system through one line (feeding) and return through the other (return). It is worth paying attention to the fact that the boiler is a two-circuit gas wall mounted 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 drawn 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 carrier that will remove insoluble compounds. If the hot water circuit breaks, the boiler can operate in the heating mode of the room. Thus, you will not be sitting in a cold apartment or house in winter.

About how the DHW system works (hot water supply)

If you switch gas heating boilers wall-mounted two-circuit in summer mode, then only the heating system of the carrier for domestic needs will function. In fact, the batteries will be cold, and hot water will flow from 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 medium is directed. When water passes through the carrier, it heats up and goes straight to the hot water circuit. The process begins with the start of the relay, whose contacts are closed when the media consumption is more than 2.5 liters. The microprocessor is commanded to ignite the burner, and then the gas valve gradually opens. Power increases with increasing. Then the device goes into a smooth temperature control mode. It is worth noting that the gas heating boilers wall-mounted two-circuit from all manufacturers are arranged so that the burner switches off when the set temperature is exceeded by 5 degrees, and turns on when the temperature of the carrier drops by 1 degree.

Two-circuit gas turbine boiler: advantages and disadvantages

The essence of the turbocharged models is that there is forced ventilation. The air supply for the combustion process of the gas, as well as the discharge of the combustion products, is carried out with the help of a built-in fan. In this case, there is a pair of air ducts of small diameter. The process takes place simultaneously. The combustion products are released into the environment, and the oxygen necessary to maintain combustion, on the contrary, is fed to the boiler. The fans are mounted inside the boiler. But it should be noted that the forced tap is suitable for aggregates with a capacity of no more than 30 kW. As for the advantages, they are obvious, there is no need to build a chimney. Two pipes, one large diameter, the second small one, are taken out to the street. The first one is used for oxygen supply, the second one is used for flue gas discharge. But there are disadvantages, the fact is that gas heating boilers, two-circuit, have a more complex design, and it is not always possible to make a hole in the wall. Let's look at another important point.

User's manual

It is difficult to give specific recommendations, due to the fact that the recommendations of each manufacturer are their own. But there are several general rules that must be fulfilled for the normal operation of your boiler. First, there is a special filter between the pipeline and the heat exchanger. So, periodically it needs to be cleaned or changed. How often 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, it is necessary to add water to the system, if higher, then vice versa, to drain a certain amount of media. Often there are two valves, as well as a pressure gauge. If the arrow is in the green zone, then everything is fine. There is one trick, which is to reduce the amount of scale in the system. It consists in not raising the temperature of the carrier above 45 degrees Celsius. With the rise, the decomposition of salts and other elements that form a dense deposit occurs.

Diagram of a double-circuit boiler

Let's talk about how to properly connect the device. This is often done by professionals, but if you decide to do it yourself, then without certain knowledge it will not work. First, a two-circuit gas boiler, the principle of operation of which we have already considered, should provide for a mechanical filter at the inlet. It is desirable to pre-install the cut-off valve on the boiler return. This is done so that you do not need to airlift the system when the unit breaks down. After the boiler is installed directly, further communications, that is, water supply, gas, and also install coaxial pipes to divert the combustion products and supply oxygen. In any case, the system is started under the control of the gas service. Do not forget that the boiler is a gas dual-circuit floor or wall mounted must be installed strictly in accordance with the level.

Conclusion

If you are going to install the device yourself, then you will definitely need a two-circuit gas boiler circuit. Often it makes sense to pay and entrust this matter to professionals. The reason is that you will be dealing with an explosive gas, so any leakage can lead to serious consequences. Here, in principle, and all on this topic. Now you know how a double-circuit gas boiler works. Instructions for use are mandatory for reading, 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, if you fail, you will have to spend your own money.