How Often Should I Top Up The Pressure In My Heating System?

We often get asked how often should I top up the pressure in my heating system? All central heating systems have a pressure gauge somewhere on or near the boiler that shows the pressure in the heating system. Occasionally this needs to be topped up, usually after bleeding a radiator. What if your boiler keeps on losing pressure? How much pressure loss is to be expected and when is it the time to call out a professional heating engineer to take a look at your system?

How Often Should I Top Up The Pressure In My Heating System?

When the heating system is cold, it should have a residual pressure somewhere between 1 and 1.5 bar. This is shown by the pressure gauge indicator needle in a green section. If the pressure falls to below 0.5 bar (indicated by a red section), then some water has been lost from the system and so it must be replaced. The pressure in the central heating system usually needs to be topped up once or twice a year at most. If you find you are having to repressurise your heating system more frequently, contact a Gas Safe registered heating engineer.

What if the pressure is too high?

You may have a red part of the dial the other side of the green part. This indicates that the pressure is too high: usually at or above 2.75 bar. If the pressure gauge indicates high pressure (the system has been over filled), you’ll need to bleed a radiator until the gauge falls back down to the safe level.

What about the pressure when the heating is on?

If the pressure increases by more than one bar when the heating has reached temperature, you may need your expansion vessel repressurising. This has to be done by a service engineer; you can’t do it yourself.

L&W Heating and Plumbing

For more information or advice, we recommend LW Heating and Plumbing. Call your local office on one of the regional numbers:-

Boiler Installation Newton Le Willows Specialist 01925 394260
Boiler Installation St Helens Specialist 01744 776140
Boiler Installation Warrington Specialist 01925 394260
Boiler Installation Wigan Specialist 01942 417220
Boiler Installation Runcorn Specialist 01925 394260
Boiler Installation Widnes Specialist 01925 394260