If your boiler pressure gauge needle is below 1 bar or in the critical red zone you will need to repressurise the system.
To increase the boiler pressure you will need to add mains cold water to the system using the external filling loop. Make sure that the boiler is turned off and completely cooled down before you start.
You should only have to increase the boiler pressure once or twice a year.
But, if your boiler keeps losing pressure this could mean that the water from the system is leaking. Please always contact a Gas Safe engineer to repair the boiler if you spot a leak – you can find an engineer near you with Gas Safe’s – Find An Engineer Tool.
Ready to top up? Head to our full guide on how to fill a pressurised heating system.
If you have a combi boiler like a Worcester Bosch, you can easily repressurise the system using the keyless filling link. at the bottom of the boiler.