Why does the pressure drop in the heating system? Air relief valve from the heating system. What pressure should be in the heating system
Today it is less and less popular in private houses. Recently, a closed-type heating scheme has been developing quite rapidly; it involves the use of gas equipment. Even if the installation has been carried out correctly, a pressure drop may occur. Even a new system sometimes faces such a problem, and there are many reasons for this.
Heating system device
The boiler acts as the main equipment for laying the heating system. It transfers the thermal energy released during fuel combustion. As a result, the coolant heats up. Depending on which boiler is used, different fuels can be used, namely:
- natural gas;
- coal;
- firewood;
- peat.
Today you can find such heating schemes where electricity acts as a heat source. However, this approach is quite expensive, although it is considered the safest. When installing heating equipment, an expansion tank of the type must be placed in front of the boiler. It is required to balance the water pressure.
Expansion tank operation
Pressure stabilization equipment has a membrane that is designed to separate the air and the working space. The function of the expansion tank is to take in the excess volume of water created 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 devices 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 water temperature drops, the pressure drops, and the water that was previously in the tank is pushed out of it.
Air heating
The room is heated thanks to batteries that are in each room. Depending on what material is used, the equipment can be:
- cast iron;
- aluminum;
- bimetallic;
- steel.
When considering heating equipment and systems, it is better to prefer bimetallic radiators as they have excellent heat dissipation. Water enters the heating devices through a branched system. To ensure a fast and uniform movement of water, it is used. Systems where the coolant moves by gravity work on the same principle. In this case, the air relief valve from the heating system acts as one of the important elements, this should also include pressure gauges, as well as shut-off valves.
Why does the pressure drop
In a closed heating system, pressure drops due to:
- the presence of air;
- water leaks;
- use of aluminum radiators.
If we are talking about a coolant leak, then it can occur in those places where the elements were connected, as well as the batteries are located and Water can be lost in the area of the elements affected by corrosion. Sometimes a ruptured diaphragm will cause the coolant to leak.
To check for leaks, press on the nipple, which is located on top of the tank. If air and water are released, then we can safely talk about a coolant leak. Otherwise, only air is released. After checking the entire line, leaks may not be found, and the problem is related to other reasons.
The reason for the pressure drop in the presence of air
Quite often, heating equipment and systems are faced with a drop in pressure. This may be indicated by the presence of air. If there are plugs, then the technical requirements for the process of filling the system with water could be violated. Sometimes the coolant is poorly prepared, as a result of which a certain volume of dissolved air remains in it.
The coolant can be airborne, in this case suction occurs, and the connections remain not so tight. Sometimes it also happens that the air relief valve from the heating system does not work correctly, it may be poorly adjusted or clogged. Each of these problems can cause noise in the system. This phenomenon cannot be called normal, in addition, it is harmful to heating.
Consequences of a pressure drop in the system
If air accumulates in the heaters, this can cause piping noise, which weakens welds and screw connections. If you have already figured out why the pressure in the heating system drops, then you should also think about what consequences this can lead to.
For example, if it is impossible to air the system, it cannot be adjusted, sometimes this becomes the reason for stopping the circulation of water in individual risers and batteries. The consequence may also be the defrosting of the system. If the movement is not completely stopped, then the efficiency will decrease and fuel consumption will increase. If the pressure in the heating system of a private house drops, then damage to the pump impeller will help, because the load will increase.
What should be the pressure
If you are also thinking about the question of what pressure should be in the heating system. If the circuit is open, the pressure in the expansion vessel will be equal to atmospheric, while the pressure gauge will indicate a value of 0 bar. Immediately after the pumping equipment, there will be a pressure in the pipeline, which will be equal to the pressure that the unit is capable of developing. If we are talking about a closed system, then everything is much more complicated.
To improve the efficiency of work and prevent air from entering the water, the static component is artificially increased. There is a simplified way to help determine the pressure in such a circuit. It is necessary to determine the elevation difference by finding the high and low points of the network. This value is multiplied by 0.1. Calculations will allow you to determine the static pressure, 0.5 should be added to this figure, this will allow you to calculate the required pressure in the system. In practice, 0.5 bar may not be enough. For this reason, it is customary to assume that in a closed system the pressure is 1.5 bar, but during operation this value increases to 2 bar.
After you know what pressure should be in the heating system, you should know that with its increase, the operation of the circuit improves. But this figure is limited by the characteristics of the equipment. Household heat generators are capable of working only at 3 bars, however, you can also find very weak devices that are designed for only 1.6 bars. Therefore, when making the adjustment, it is necessary to achieve an indicator 0.5 bar lower than the value indicated in the passport of the boiler equipment. Otherwise, the pressure relief valve will operate.
Purpose and types of air relief valve
If you are wondering why the pressure in the heating system is dropping, then you should first use the air relief valve. In industrial boilers, before entering the boiler, water goes through the stage of removing dissolved air. If initially it contained up to 300 g / m 3, then after it becomes suitable and corresponds to indicators of 1 g / m 3. But such technologies are quite expensive, so they are not used in private housing construction.
If you are also worried about why the pressure in the heating system drops, then the coolant may be oversaturated with air. This interferes with the circulation of the liquid, while some areas overheat, while others cool down. To solve the described problem, air vents are used, which are automatic or manual. Each variety is installed in different locations where there may be a risk of air accumulation. Valves called can have a radiator and traditional design. As for the configuration, it can be angular or straight.
How to exclude air from entering the system
In order not to face the question of why the pressure in the heating system drops during operation, it is important to correctly commission the equipment. Before starting, the system as a whole and each connection separately are inspected. The system must be pressure tested, for this the compressor is pressurized 25% more than the working head. If a strong decrease in pressure has not occurred within 20 minutes, then the system is equipped correctly, it can be put into operation.
But if the pressure in the heating system constantly drops, then it is important to find the leak and eliminate it. A characteristic whistle may indicate such a problem. It is necessary to fill the system with cold water, this should be done gradually. Before starting, all taps are opened, which will allow air to be released. Unscrew the plugs in the batteries, this will remove air from the system. If the design allows, then the valve should be opened to vent the circuit.
