Your boiler pressure needs to be operating at the correct pressure for your central heating system to function properly. If your boiler happens to lose pressure or if the pressure becomes to high, you are at risk of your boiler shutting off or 'locking out'. When your heating is on, your boiler should b e operating at a pressure between 1.5 and 2 bar. When the heating is off, your boiler should be operating at a pressure between 1 and 1.5 bar. The majority of new, modern boilers will highlight this on the pressure gauge in green to help you visually see the current operating pressure of your boiler.