Why does the pressure in the heating boiler rise

The pressure in the heating system above normal causes the safety group of the boiler equipment to periodically release the excess liquid through a safety valve. In this operating mode, all parts of the circuit begin to experience an increased load, which can cause a malfunction, therefore, it is urgent to find out why the pressure in the system increases.

Reasons for pressure increase

Only a professional heating engineer can detect the exact malfunction of the boiler. That is, to determine and repair the breakdown itself, which caused an increase in pressure in the heating system, will not work. The main reasons for the increase in pressure that occur during external breakdowns of the boiler are as follows:

1. Violation of the integrity of the heat exchanger. Due to the long operating time, the walls of the equipment may crack. The causes of cracks are factory defects, insufficient strength, water hammer or equipment wear. Fluid is added to the circuit every few days. Visual leakage cannot be detected - the coolant drains very weakly, while the burner is in operation, the moisture present begins to evaporate. It is necessary to change the heat exchanger, it can be sealed in very rare cases.
2. Pressure increases due to an open make-up valve. Due to the low pressure in the boiler circuit and increased in the pipeline through the feed valve in the heating pipe begins to pass the "excess" liquid. The pressure rises until its withdrawal through the safety valve is required.
3. If the pressure in the pipeline drops, the coolant closes the fluid supply to the boiler, in which case the pressure in the system decreases. The same problem can happen with a broken make-up valve. You must either block it, or change it.
4. Increase due to three-way valve. During valve failure, fluid from the expansion vessel will begin to flow into the circuit. The three-way valve must be changed or periodically cleaned.
5. The pressure gauge readings remain in one place. If during changes in the operating mode of the boiler equipment with an increase or decrease in temperature on the pressure gauge the arrow does not move, the pressure gauge is broken. It needs to be replaced.

Why is the pressure in closed boilers increasing

The main reasons why the pressure rises are as follows:

• the heating circuit is filled from the top;
• fast filling with coolant during start-up;
• shattered pump fan through which air passes;
• air vent failure;
• after repair, the system did not bleed air.

The heating circuit must be filled from the bottom, and the safety taps must be open. It is necessary to fill up gradually, until the liquid starts to drain from the safety valves. Before you start filling the heating circuit, all the air inlet parts must be treated with soapy water, so you can check their normal operation.

Important! If the discharge pump passes air, then it is he who causes the increased pressure.

Reason for increased pressure in open systems

In an open system, with the correct calculation of the slopes of the pipes, the air enters the expansion tank. Air plugs can appear only during improper filling of the circuit with liquid at the start-up.

During the appearance of this problem, air is vented through safety taps located on the radiators.

Attention! When it is not possible to lower the pressure, then it will probably be necessary to completely drain the heating circuit during the next start-up.

Other reasons

An increase in pressure can also occur for the following reasons:

1. Closed shut-off valves. As a result, the pressure at the supply of the thermal medium increases and the protection of the boiler equipment is turned on. It is necessary to open all the valves.
2. The expansion tank is located right after the pumping equipment. Thus, the pressure instantly increases, and almost immediately drops off, while its differences are noted. This situation can lead to water hammer in the heating circuit. To get rid of this problem, the expansion capacity must be installed on the return circuit - in the area with a low temperature of the thermal carrier. The pump is installed in front of the boiler equipment, after the expansion tank.
3. If a coarse filter is located, its mesh may become dirty. As a result, the pressure in the pipeline increases. Cleaning the strainer can help reduce water pressure. The simplest carbon filter needs to be cleaned every 5 years. Rinsing filters are quite expensive, but the coolant cleans this equipment much better.
4. Failure of the automatic boiler system, breakdown of sensors. Not all the time you can determine why this happened. The reason is a manufacturing defect, the use of poor quality materials during the manufacture of controls, improper installation. You can fix the failure yourself only by knowing the error code. If the documentation for the equipment does not contain this code and troubleshooting methods, you must contact the after-sales service.

The correct and continuous operation of the heating system depends on the quality of installation, the proper operation of the equipment, as well as support in the normal pressure system.