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Boiler feeling under pressure? Luckily, it's a super quick fix

Heating Advice

Low pressure but not sure how to add pressure to your central heating system? Follow our tips to correct the pressure, and know when it's time to call in a professional.

Most boilers lose pressure at one point or another, usually due to the radiators being bled, or a small leak in the pipes. You can usually re-pressurise the boiler yourself, without needing to pay a professional.

When do I need to re-pressurise my boiler?

Re-pressurising your boiler will help to raise the pressure if it has dropped too low. You can check your boilers pressure using the pressure gauge display.

The main causes of low pressure include leaks or recently bled radiators which both allow pressure to escape the central heating system. If you haven't bled your radiators, you should check the pipes around the system for any leaks. You can fix any leaks with sealant from most DIY shops, before you start re-pressurising the boiler.

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How do I re-pressurise my boiler?

Re-pressurising your boiler is relatively easy and you should be able to do it yourself. To re-pressurise the boiler, you'll need to find the filling loop, which is usually underneath your boiler. The filling loop is a flexible, silver hose with a valve at one or both ends.

Release the valves one at a time ?? once they're open you should hear water filling into the system. Keep an eye on the pressure gauge, and close the valves when it's displaying between 1.5-2. It's crucial to make sure that you've closed both valves properly as leaving one loose could lead to the pressure becoming too high.

If you're struggling to re-pressurise the boiler, it's best to get a professional engineer to do it for you.

What if the pressure goes back down?

If your pressure returns to less than one bar after you've re-pressurised, it's a sign that there is something else wrong, such as a leak inside the boiler. This could damage other parts within the boiler, so it's best to get this looked at by a Gas Safe engineer as soon as possible.

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