Boiler pressure can fluctuate for different reasons. If you find that your boiler pressure is too high, this guide will explain how to reduce it yourself and return the pressure to its correct setting.
What pressure should my boiler be?
Your boiler’s pressure is usually displayed on the built-in pressure gauge, and should read around the 1 bar mark when you’re not running any hot water and the heating isn’t turned on. Therefore, 1 bar is a low-pressure setting.
When the heating is turned on, your boiler pressure should be between 1.5 and 2 bars. Most boilers will highlight this area in green on the pressure gauge, clearly showing you that the pressure setting is correct.
Why is my boiler pressure too high?
Once the boiler begins to heat water, the heated water expands and causes the pressure gauge to increase. With an expansion vessel, boilers are well-set to control these quick leaps in pressure so you don’t need to worry if the boiler shows a higher pressure than you expected when you are both using the central heating and running hot water.
How to reduce your boiler pressure
Follow these six steps to help lower your high boiler pressure:
- Switch off your boiler and wait for the heating system to cool
- Identify and check the boiler pressure gauge
- If it’s above 2 bars, you’ll need to reduce the pressure
- Ensure the filling loop or relief valve is tightly closed
- Bleed your radiators to release trapped air from the heating system
- Check to see if the boiler pressure returns to its correct setting
Is your boiler pressure too low?
If your boiler pressure is too low (anything below one bar), you may need to bleed your radiators or there may be a leak in the heating system.
Find out exactly what you’ll need to do by reading our useful guide on how to repressurise a boiler with low pressure.
Boiler pressure still too high?
If your boiler pressure still persists to be too high, there could be one of two issues;
- Expansion vessel needs repressurising
- Fault with the filling loop
You may need to re-pressurise the expansion vessel, or you could have a fault with the filling loop. However, you won’t be able to do this yourself and will need to call a Gas Safe registered engineer who can come and diagnose the issue for you.
