When water is heated in water heaters, the pressure rises

What should I do if, when heating water in an electric water heater, the pressure sensor installed on the automatic pressure switch of the water pump shows an increase in pressure (arrow in the "red" zone)?

Sergei

Expert Answer

Water, like any other body, when heated increases in volume, therefore, in order to avoid damage to the boiler, it is equipped with a safety valve. At normal pressure in the container, the protective element of the system is in the closed position. When the pressure exceeds a critical value, the valve opens and excess fluid is discharged to the outside. The safety device is configured to operate when the pressure rises above 7 atm.

An increase in pressure in the water heater above this value in 100% of cases indicates a malfunction of the safety valve. Most often, this device fails due to contamination or scale formation. It is not recommended to repair or clean the protective mechanism - it is better to replace it with a new one. At the same time, it is better not to experiment on cheap Chinese valves, but to purchase a high-quality device made in Italy or Germany.

In your case, in addition to checking the safety system, you should also check the check valve. The situation described by you indicates that it does not hold hot water in the boiler, passing it into the “cold” water supply and provoking the increase in pressure you described. Perhaps correcting the situation will help cleaning the part from scale and dirt. Otherwise, replace the valve with a reliable brass product.