Normal pressure in a closed heating system is very important. Firstly, this is a warm room in the winter, and secondly, the normal operation of all components of the boiler. But the arrow is far from always in the range we need, and there may be a lot of reasons for this. High and low pressure in the heating system leads to blocking of the pump and the absence of warm batteries. Let's talk in more detail about how many atmospheres should be in our pipes and how to fix typical problems.
Some general information
Even at the stage of designing the heating system , pressure gauges are installed in different places. This is necessary in order to control the pressure. When the device detects a deviation from the norm, it is necessary to take any action, a little later we will talk about what to do in a particular situation. If no measures are taken, the heating efficiency decreases, and the life of the same boiler is reduced. Many people know that the most detrimental effect on closed systems is provided by water hammers, for damping of which expansion tanks are provided. So, before each heating season, it is advisable to check the system for weaknesses. This is done quite simply. It is necessary to create excess pressure and see where it appears.
Low and high system pressure
Often the pressure drop in the heating system is due to several factors. Firstly, this is a coolant leak, which is the most common cause of a decrease in atmospheres. Leakage is most often located at the junction of parts. If it is not there, then most likely the problem is in the pump. Scale in the heat exchanger is another reason for lowering the pressure in the system. The same applies to the physical wear of the heating element. But the increase in pressure happens due to the formation of an air plug. Also, the reason may be the difficult movement of the carrier through the pipes due to obstruction in the filter or sump. Sometimes, due to automation failures, excessive recharge of the system occurs, in this case the pressure also rises.
How to fix the situation with a difference?
Everything is extremely simple here. First, you need to look at the pressure gauge, which has several characteristic zones. If the arrow is in green, then everything is fine, but if it is noticed that the pressure in the heating system is falling, the indicator will be in the white zone. There is still red, it signals an increase. In most cases, you can cope on your own. First you need to find two valves. One of them is used for pumping, the second - to bleed the media from the system. Then everything is simple and clear. If there is a lack of media in the system, it is necessary to open the discharge valve and follow the pressure gauge installed on the boiler. When the arrow reaches the desired value, close the valve. If bleeding is needed, everything is done in a similar way with the only difference being that you need to bring a bowl with you where the water from the system will be drained. When the gauge needle shows the norm, tighten the valve. Often, this is how the differential pressure in the heating system is "treated". Now let's move on.
What should be the operating pressure in the heating system?
But to answer this question in a nutshell is quite simple. Much depends on what house you live in. For example, for autonomous heating of a private house or apartment, it is often considered normal 0.7-1.5 Atm. But again, these are approximate figures, since one boiler is designed to work in a wider range, for example, 0.5-2.0 Atm, and the other in a smaller one. This must be found in the passport of your boiler. If there is none, stick to the middle ground - 1.5 Atm. The situation is completely different in those houses that are connected to central heating. In this case, it is necessary to be guided by the number of storeys. In 9-storey buildings, the ideal pressure is 5-7 bar, and in high-rise buildings - 7-10 bar. As for the pressure under which the carrier is supplied to the building, then most often it is 12 Atm. You can lower the pressure using pressure regulators, and increase it by installing a circulation pump. The latter option is extremely relevant for the upper floors of tall buildings.
How does carrier temperature affect pressure?
After the closed water supply system is installed, a certain amount of coolant is pumped. As a rule, the pressure in the system should be minimal. This is because the water is still cold. When the carrier is heated, it will expand and, as a result, the pressure inside the system will increase slightly. In principle, it is wise to control the amount of atmospheres by adjusting the temperature of the water. At present, expansion tanks are used, they are also hydraulic accumulators that accumulate energy inside themselves and do not allow an increase in pressure. The principle of operation of the system is extremely simple. When the working pressure in the heating system reaches 2 Atm, an expansion tank is turned on. The accumulator absorbs excess coolant, thereby maintaining the pressure at the required level. But it happens that the expansion tank is full, there is nowhere to go for excess water, in this case a critical overpressure may occur in the system (more than 3 Atm.). To save the system from destruction, a
safety valve is turned on
, removing the excess volume of water.
Static and dynamic pressure
If we explain in simple words the role of static pressure in a closed heating system, then we can put it something like this: this is the force with which the liquid presses on the radiator and pipe, depending on the height. So, for every 10 meters there is +1 Atm. But this applies only to natural circulation. There is also dynamic pressure, which is characterized by pressure on the pipeline and radiators during movement. It is worth paying attention that when installing a closed heating system with a circulation pump, static and dynamic pressure are added, while taking into account the features of the equipment. So, the cast-iron battery is designed to operate at 0.6 MPa.
Pipe diameter and degree of wear
You must remember that you need to consider the size of the pipe. Often, residents install the diameter they need, which is almost always slightly larger than standard sizes. This leads to the fact that the pressure in the system decreases slightly, due to the large amount of coolant that will fit in the system. Do not forget that in corner rooms the pressure in the tubes is always less, since this is the most distant point of the pipeline. The degree of wear of pipes and radiators also affects how the pressure in the heating system of the house will be. As practice shows, the older the battery, the worse. Of course, not everyone can change them every 5-10 years, and it is not advisable to do this, but from time to time, preventive measures will not hurt. If you move to a new place of residence and know that the heating system is old there, then it is better to immediately change it, so you will avoid many troubles.
About Leak Testing
It is imperative to check the system for leaks. This is done so that the heating operation is efficient and has no malfunctions. In multi-story buildings with central heating, they often resort to a cold water test. In this case, if the water pressure in the heating system drops by more than 0.06 MPa in 30 minutes or 0.02 MPa is lost in 120 minutes, it is necessary to look for places of gusts. If the indicators do not go beyond the norm, then you can start the system and begin the heating season. Hot water testing is carried out immediately before the heating season. In this case, the carrier is supplied at a pressure that is maximum for the equipment.
Conclusion
As you can see, dealing with this issue is quite simple. If you use autonomous heating, then the working pressure in the system should be approximately 0.7-1.5 Atm. In other cases, much depends on the number of storeys of the building, as well as the degree of wear of batteries and radiators. In all cases, care must be taken to install an expansion tank, which will eliminate the occurrence of water hammer and, if necessary, lower the pressure. Remember that it is advisable to clean pipes from scale and other decay products at least once every 2-3 years before the heating season.