Double-circuit boilers today are the most popular on the market. This is due to many 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 double-circuit gas boiler is. The principle of operation of the device, as well as the connection diagram and operating instructions are also affected. This article is suitable for those who want to deal with 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, it is heating and maintaining the set water temperature for the heating system, and secondly, heating the carrier for use for household purposes. Thus, not only is it warm in your home, but there is also hot water. This is a significant difference between a double-circuit boiler and any other. We can make a simple conclusion 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 capacities. There are models from 12 to 35 kW on the market today. This is enough to heat a large room of 350-400 square meters. The performance 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 consider all the advantages. Firstly, this is a significant gas saving. This was achieved through the use of modern heat exchangers. By the way, the hydraulic system made the operation of the units completely silent, therefore a double-circuit gas boiler can be installed in any convenient place. Dimensions in most cases allow installation without any problems. If the floor option is not suitable, then there is always the opportunity to install the device on the wall, which is especially true for small apartments, where every square meter is important. The operation of the double-circuit boiler is completely autonomous, which is facilitated by the corresponding equipment (pump, expansion tank, ECU and safety system).
A bit about the cons
Nothing lasts forever, nor is it perfect. The double-circuit boiler has several disadvantages. Firstly, it should be noted that there is a noticeable loss of water at the initial stage. Consider a specific example. So you turned on the hot water, the additional coolant automatically started working. For hot water to go, you need to wait about 30-40 seconds, depending on the brand of the boiler. Everything that goes from the crane until this time is called a loss. We can say with great certainty that this is not such a big drawback. If it is necessary to warm the carrier for household purposes, the double-circuit gas boiler does this in flow mode without the possibility of accumulation. Let's go ahead 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 one can also heat water, but this has already been said. If you need to warm the room, the principle of work 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 is 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, the circulation pump starts and supplies water from the heat exchanger (preheated) to the system. The pressure in the system, which should not fall below 0.5-0.7 Bar, is also taken into account. If necessary, the microprocessor sends a signal to the burner, which heats the media to the desired temperature.
The principle of operation of the boiler: part 2
But this does not end there. After switching on, the boiler starts to work in increasing order. First at minimum power, and eventually reaches its maximum. When the gas wall - mounted double-circuit boiler heats the carrier at a certain stage to a predetermined temperature, the unit switches to modulation mode. If the power is exceeded at the first start-up, the microprocessor sends a signal to turn off the burner. Re-activation is carried out after three minutes. The combustion chamber is metal and has a special heat-resistant winding. Above it is a heat exchanger, below it is a burner. The latter ignites exactly at the moment when the temperature of the carrier in the system drops and you need to heat the water. Together with it, a circulation pump is also included in the work, designed to drive water in a closed system. When the set temperature is reached, the gas wall bypass boiler enters standby mode. In some models, the burner burns, but at a minimum, in others it goes out and lights up when gas is supplied.
A little more about the features of work
To prevent media from entering the secondary circuit, a three-way valve is used. Thus, it was possible to achieve the supply of heated water from the boiler to the system through one line (supply) and return through the other (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 plaque. 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 supply circuit breaks, then the boiler can work in the heating mode of the room. Thus, you will not sit in the winter in a cold apartment or house.
How the hot water system works (hot water supply)
If you switch gas wall-mounted double-circuit heating boilers to summer mode, then only the carrier heating system for domestic needs will function. In fact, the batteries will be cold, and hot water will come 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 carrier goes. When water passes through the carrier, it heats up and flows directly into the hot water circuit. The process begins with the start of the relay, the contacts of which close when the flow rate of the carrier is more than 2.5 liters. A command is issued from the microprocessor to ignite the burner, and then the gas valve is gradually opened. Power is increasing. Further, the device enters the smooth temperature control mode. 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 decreases by 1 degree.
Double-circuit turbocharged gas boiler: advantages and disadvantages
The essence of the turbocharged models is that there is
forced ventilation. Air supply for the gas combustion process, as well as the removal of combustion products is carried out using the built-in fan. In this case, there is a pair of small diameter ducts. The process takes place simultaneously. The combustion products enter the environment, and the oxygen necessary to maintain combustion, on the contrary, is supplied to the boiler. Fans are mounted inside the boiler. But it is worth paying your attention that forced withdrawal is suitable for units with a capacity of not more than 30 kW. As for the advantages, they are obvious, there is no need to build a chimney. Two pipes are led into the street, one of large diameter, the second of small. The first is used to supply oxygen, the second - to remove combustion products. But there are drawbacks here, the fact is that gas double-circuit heating boilers have a more complex structure, and it is far from 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 each manufacturer has its own recommendations. But there are several general rules that must be followed for the normal operation of your boiler. Firstly, there is a special filter between the pipeline and the heat exchanger. So, periodically it needs to be cleaned or replaced. Find out how often to do this 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 higher, then vice versa, lower a certain amount of media. Often there are two valves, as well as a pressure gauge showing pressure. 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 increasing the temperature of the carrier above 45 degrees Celsius. With increasing decomposition of salts and other elements that form a dense coating.
Double-circuit boiler scheme
Let's talk about how to connect the device correctly. Often, professionals do this, but if you decide to do it yourself, then without certain knowledge, nothing will come of it. Firstly, a double-circuit gas boiler, the principle of operation of which we have already considered, should 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 it is not necessary to air the system when the unit breaks down. After the boiler is mounted directly, then communications are introduced, that is, water supply, gas, and also coaxial pipes are installed to exhaust the combustion products and supply oxygen. In any case, the start-up of the system is carried out under the control of the gas service. Do not forget that the gas double-circuit boiler floor or wall must be installed strictly in level.
Conclusion
If you are going to install the device yourself, then you will definitely need a double-circuit gas boiler circuit. Often, it makes sense to pay and entrust this matter to professionals. This is due to the fact that you will deal with explosive gas, so any leak can lead to serious consequences. Here, in principle, and everything on this topic. Now you know how a double-circuit gas boiler works. The instruction manual is required to 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 in the event of a breakdown.