Why does the pressure in the heating system drop? The valve of air discharge from the heating system. What pressure should be in the heating system

Oven heating today is less popular in private homes. Recently, the heating circuit of a closed type is developing quite rapidly, it involves the use of gas equipment. Even if the installation has been carried out correctly, pressure drop may occur. With this problem, even a new system sometimes collides, and for this there are many reasons.

The device of heating system

As the main equipment when laying the heating system is a boiler. It transfers the heat energy released when the fuel burns. As a result, the heat carrier is heated. Depending on which boiler is used, different fuel can be used, namely:

• natural gas;
• coal;
• firewood;
• peat.

Today, one can also find such heating schemes, where electricity acts as a source of heat. However, this approach is rather expensive, although it is considered the safest. When installing the heating equipment, the expansion tank of the closed type heating system must be located in front of the boiler. It is necessary for balancing the water pressure.

Expansion Tank Operation

Equipment for stabilizing the pressure has a membrane, which is designed to divide the air and working space. The function of the expansion tank is to take an extra volume of water formed during the expansion process when exposed to elevated temperatures.

After the first task is completed, the water must be returned to the system. When the coolant expands, the pressure in the instruments and pipes increases, and excess water flows into the tank. This provokes the expansion of the membrane, as a result of which the volume of air decreases, which leads to an increase in pressure. When the temperature of the water drops, the pressure decreases, and the water that was previously in the reservoir is pushed out of it.

Heating of air

The room is heated thanks to the batteries that are in each room. Depending on what material is used, the equipment can be:

• Cast iron;
• Aluminum;
• Bimetallic;
• Steel.

When heating equipment and systems are considered, it is better to prefer bimetallic radiators, since they have excellent heat transfer. In the heating appliances water comes through a branched system. A circulating pump is used to ensure fast and uniform water movement . The same principle applies to systems where the coolant moves by gravity. The valve of air discharge from the heating system in this case acts as one of the important elements, here it is necessary to include also manometers, and also stop valves.

Why the pressure drops

In a closed heating system, the pressure drops due to:

• Presence of air;
• Water leakage;
• Use of aluminum radiators.

If it is a leakage of the coolant, it can occur in the places where the elements were connected, as well as the batteries and the expansion tank. Water can also be lost in the area of the corrosion-affected elements. Sometimes a torn membrane causes leakage of the coolant.

To check the leak, press the nipple that is located on top of the tank. If air and water are released, then we can safely talk about the leakage of the coolant. Otherwise, only air is released. After checking the entire pipeline, leaks may not be detected, and the problem is related to other causes.

Cause of pressure drop in the presence of air

Quite often, heating equipment and systems face a drop in pressure. This may indicate the presence of air. If the plugs appeared, the technical requirements for filling the system with water could be violated. Sometimes the coolant undergoes poor preparation, as a result of which a certain amount of dissolved air remains in it.

The heat transfer medium can be airborne, in this case, a suction occurs, and the connections remain less dense. Sometimes it also happens that the vent valve from the heating system is not working properly, it may be poorly regulated or clogged. Each of these problems can cause noise in the system. This phenomenon can not be called normal, in addition, it is harmful for heating.

The consequences of pressure drop in the system

If air accumulates in the heaters, this can cause noise in the pipelines, which weakens the welds and threaded joints. If you have already figured out why the pressure in the heating system is falling, you should also think about the consequences of this.

For example, if the system can not be de-aerated, it can not be adjusted, sometimes it causes the circulation of water in separate risers and batteries to stop. A consequence can also be a defrost system. If the traffic ceased not completely, the efficiency will decrease and fuel consumption will increase. If the pressure in the heating system of a private house falls, then the pump impeller will be damaged, because the load will increase.

What should be the pressure

If you also pondered the question of what kind of pressure should be in the heating system. If the circuit is open, the pressure in the expansion tank will be equal to atmospheric pressure, while the pressure gauge will show a value of 0 bar. Immediately after the pumping equipment in the pipeline there will be a pressure that will be equal to the head that is capable of developing the unit. If it is a closed system, then everything is much more complicated.

To improve efficiency and prevent air from entering the water, the static component is artificially increased. There is a simplified method that helps determine the pressure in such a scheme. It is necessary to determine the height difference, finding the high and low points of the network. This value is multiplied by 0.1. Calculations will determine the static pressure, this figure should be added 0.5, and this will allow to calculate the required pressure in the system. In practice, 0.5 bar may not be enough. For this reason, it is commonly assumed that in a closed system the pressure is 1.5 bar, while during operation this value is increased to 2 bar.

Once you know what pressure should be in the heating system, you need to know that with its increase, the circuit's performance improves. But this figure is limited by the characteristics of the equipment. Household heat generators are able to work and only at 3 bars, but you can also find very weak devices, which are calculated only for 1.6 bars. Therefore, when performing the adjustment, it is necessary to achieve the indicator by 0.5 bar lower than the value indicated in the boiler equipment passport. Otherwise, the pressure relief valve will operate.

Purpose and types of the valve for venting

If you are wondering why the pressure in the heating system is falling, you should first use the air vent valve. In boilers for industrial purposes, the water passes through the stage of removal of dissolved air before entering the boiler. If initially it contained up to 300 g / m ³ , then it becomes suitable and corresponds to the indicators of 1 g / m ³ . But such technologies are rather expensive, therefore they are not used in private housing construction.

If you also care about why the pressure in the heating system drops, the coolant can be oversaturated with air. This prevents the circulation of liquid, some parts are overheated, while others - cool. To solve the described problem, airmen are used, which are automatic or manual. Each species is installed in different places, where there may be a danger of air accumulation. Valves, called Mayevsky cranes, can have radiator and traditional execution. As for the configuration, it is either angular or straight.

How to prevent air from entering the system

In order to not face the question of why pressure in the heating system is falling during operation, it is important to put the equipment into operation correctly. Before launching, the system as a whole and each connection are inspected separately. The system must be pressure tested, for this the compressor is pressurized by 25% more than the working head. If within 20 minutes there was no strong reduction in pressure, then the system is properly equipped, it can be put into operation.

But if the pressure in the heating system constantly falls, it is important to find a leak and eliminate it. Such a problem can be indicated by a characteristic whistle. Fill the system with cold water, it should be done gradually. Before the start all the taps are opened, which will allow the air to be released. The plugs in the batteries should be unscrewed, this will remove air from the system. If the design allows, then the valve should be opened to extinguish the circuit.