What should the pressure gauge on my boiler be reading?

The normal operating water pressure for your boiler and central heating system is between 1.0 and 2.0 bar. If the pressure drops below 1.0 bar, you need to repressurise it.

If the pressure goes above 3.0 bar, you will see water coming from the pressure relief valve (usually on an outside wall). You can reduce the pressure by bleeding a radiator or draining some water out of the system using a drain point, usually found underneath a radiator.