How to read a boiler pressure gauge

It’s important that your boiler is running at the correct pressure - too little pressure could cause your system to cut out and too much could trigger the safety valve meaning the boiler will require a top up in pressure. This is the reason why boilers come with a pressure gauge that you can use to determine the physical force that’s being used in your heating system.

A pressure gauge is usually located on the front of your boiler and should have a green and red section that can be used to detect when the pressure is too low, too high or just right. The force that it’s calculating is that of the hot water that’s running through the sealed system. Most boilers should run between one and 1.5 bar of pressure.

It’s common for boilers to lose pressure. This is usually because some water has been lost from the system. If the pressure is showing below 0.5 bar, you could use a filling loop to draw more water into the system. You should repressurise the system until it reaches the correct level. Alternatively, if the pressure is too high, you can release some of it by bleeding your radiators.

This is why a pressure gauge is so important. 

Your heating system should be checked for leaks. If there are leaks on your system your boiler could lose pressure. The simplest way to test if there are leaks is to pressurise the system and monitor the pressure to ensure that it doesn’t drop too much. If your boiler pressure is frequently dropping, it could suggest that you have a leak in the system.

Another thing which could affect your pressure could be the expansion vessel, this should be checked by your engineer during a boiler service.

Maintaining the correct pressure in a boiler system is extremely important for boiler efficiency. This can be done by a Gas Safe registered engineer during your boiler’s annual service.