Oven heating is today less and less popular in private homes. Recently, a closed-circuit heating scheme has been developing quite rapidly; it involves the use of gas equipment. Even if the installation was carried out correctly, a pressure differential 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 when laying the heating system. It transmits the thermal energy released during fuel combustion. As a result, the coolant is heated. Depending on which boiler is used, different fuels can be used, namely:
- natural gas;
- coal;
- firewood;
- peat.
Today you can meet 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 a closed heating system must be placed in front of the boiler. It is necessary to balance the pressure of water.
Expansion tank operation
Pressure stabilization equipment has a membrane that is designed to separate air and work space. The function of the expansion tank is to take in the excess volume of water generated during the expansion process when exposed to elevated temperatures.
After the first task is completed, 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 stretching of the membrane, as a result of which the air volume 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 tank is pushed out of it.
Air heating
The room is heated thanks to the batteries that are in each room. Depending on what material is used, the equipment may be:
- cast iron;
- aluminum;
- bimetallic;
- steel.
When considering heating equipment and systems, it is better to prefer bimetal radiators, as they have excellent heat dissipation. Water enters heating devices through a branched system. A circulating pump is used to ensure fast and even movement of water . Systems operating in the same way, where the heat carrier moves by gravity, follow the same principle. The valve for venting air from the heating system in this case acts as one of the important elements, here should also include manometers, as well as stop valves.
Why does the pressure drop
In a closed heating system, pressure drops due to:
- the presence of air;
- water leakage;
- 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 batteries and an expansion tank. Water may also be lost in the area affected by corrosion. Sometimes a torn membrane causes a coolant leak.
To check for leaks, press 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 trunk, leaks may not be detected, and the problem is due to other reasons.
The reason for the pressure drop in the presence of air
Quite often, heating equipment and systems experience pressure drops. Air may indicate this. If plugs appeared, then the technical requirements for the process of 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 coolant may be air, in this case there is a leak, and the connections remain not so tight. Sometimes it also happens that the air vent 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.
The consequences of a pressure drop in the system
If air has accumulated in the radiators, this can cause piping noise, which weakens welds and threaded joints. If you have already figured out why the pressure in the heating system drops , then you should also think about what consequences this may lead to.
For example, if it is impossible to air the system, it cannot be adjusted, sometimes this causes the water circulation to stop in separate risers and batteries. The consequence may also be defrosting the system. If the movement does not stop completely, the efficiency will decrease and fuel consumption will increase. If the pressure drops in the heating system of a private house, damage to the pump impeller will help, because the load will increase.
What should be the pressure
If you also thought about the question of what pressure should be in the heating system. If the circuit is open, then the pressure in the expansion tank will be equal to atmospheric, 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 pressure that the unit is able to develop. If we are talking about a closed system, then everything is much more complicated.
To increase work 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 circuit. It is necessary to determine the height 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.
Once 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. Domestic heat generators are able to work only at 3 bars, however, you can also find very weak devices that are designed for only 1.6 bar. Therefore, when setting up, it is necessary to achieve an indicator 0.5 bar lower than the value specified in the boiler equipment passport. Otherwise, the pressure relief valve will operate.
Purpose and type of valve for venting
If you wondered why the pressure in the heating system drops, you should first use a valve to vent the air. In industrial boiler rooms, water before entering the boiler goes through the stage of removal of 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, therefore they are not used in private housing construction.
If you also care 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 individual sections 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 places where there may be a danger of air accumulation. Valves, called Mayevsky cranes, can have a radiator and traditional design. As for the configuration, it can be angular or straight.
How to prevent air from entering the system
In order not to run into the question of why the pressure in the heating system falls during operation, it is important to correctly commission the equipment. Before starting, the system as a whole and each connection are inspected individually. The system must be pressure tested; for this, the compressor supplies 25% more pressure than the working pressure. If within 20 minutes there has not been a significant decrease in pressure, then the system is correctly configured, it can be put into operation.
But if the pressure in the heating system constantly drops, it is important to find a 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 the taps open, which allows you to bleed air. The plugs in the batteries should be unscrewed, this will remove air from the system. If the design allows, the valve should be opened to air the circuit.