Do I have the right boiler pressure?

When it’s working as it should, you probably don’t give a second thought to your boiler. While it provides essential heat and hot water to your home, most of us take for granted that it will work as it should, whenever we need it to. However, boilers are complicated appliances, with different intricate parts that work together to make your central heating system perform at the right level. In order to work efficiently and reliably, all the various components of your boiler need to work properly or the performance of your radiators and hot water will be negatively affected.

One important part of your boiler that is liable to change at points is its pressure. Your boiler’s pressure can have a huge impact on the performance of your central heating system, so it’s important to make sure it’s at the right level.

In the following guide, we explain the main issues homeowners face with boiler pressure and how to resolve them.

How to check your boiler’s pressure

Firstly, you need to locate the pressure gauge on your boiler. This should be easy to identify on most modern boilers, showing a round clock-style face with numbers on with a needle pointing to where the pressure is. One area of the face will be green, which is where the pressure should ideally sit. If your boiler pressure is correct, the needle will rest in the green space between bars 1 and 1.5.

Please remember you will never need to remove the case on your boiler; this should only ever be done by a qualified Gas Safe registered engineer.

Boiler pressure too high

If the needle on your pressure gauge is above 1.5 then the pressure is too high. This signifies that the radiators need bleeding, due to trapped air within them, which causes the pressure to rise.

How to correct pressure that’s too high

You can bleed your radiators yourself to relieve the pressure, but ensure it’s done properly and carefully, with a radiator key or screwdriver. Check the pressure after bleeding and it should have dropped within the 1 and 1.5 bar range.

How to correct pressure that’s too low

Some boilers do have a filling loop, which allows you to re-pressurise your boiler yourself. If you feel confident you can follow the manufacturer’s instructions to carry this out. Afterwards, keep an eye on your pressure and if it drops again call a Gas Safe registered heating engineer as soon as possible.

Boiler pressure keeps dropping

Boiler pressure that is lower than 1 bar and dropping, is often more complicated to address, and can be a more serious cause for concern. Boiler pressure that’s too low signifies something is wrong with your system, and it won’t get sorted by itself.
If your boiler pressure keeps dropping, it could be due to:

  • A leak. If water is escaping from your boiler this can be reflected in your pressure. Look for small puddles of water around your boiler and check the corners and joints of pipes and your boiler to see if anything is escaping. A leak, no matter how small, will need to be inspected by a Gas Safe registered engineer. If you are unsure if the pipe is leaking wrap some kitchen roll around it and check it in a few hours. If the kitchen roll is wet its safe to say you have a leak.
  • Damage. Other parts of your boiler can influence the pressure, and if there has been damage to your pressure relief valve this can cause the boiler’s pressure to drop. This isn’t something you’ll be able to identify yourself but your Gas Safe registered engineer will.

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