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How to Repressurise a Boiler – Complete Guide for Anyone

Every boiler is different, so its important that you check your boiler manual. Once you have found the boiler manual, go for the manufacturer’s instructions.

Our boiler service engineer will always stress that, If you’re unsure, can’t find the strength to do this task, call a professional.

With that in mind, in this article, we are going to share with you how to re-pressurise your boiler in a easy and safe way. 

Here are the basic steps for re-pressurising your boiler (if you have a filling loop – what’s this?):

  • Step 1. Switch off your boiler. (Unless you have a digital pressure gauge display)”
  • how to switch off your boiler, image preview 1
    how to switch off your boiler, image preview 2
  • Step 2. Locate the boilers filling loop.
  • a boiler filling loop, image preview 1
    a boilers filling loop, image preview 2
  • Step 3. Fill the boiler. Open the two valves. (You will hear the mains cold water entering the system)
  • Fill the boiler, image preview 1
    Fill the boiler, image preview 2
  • Step 4. Keep the valves open until the pressure reading on your boiler display gets to 1.5 bar, don’t worry if you overfill the boiler to 1.6 bar.
  • The boiler display, image preview 1
    Fill the boiler, image preview 2
  • Step 5. Once you have reached the target pressure of 1.5 bar, close both valves, one at a time.

What is a filling loop?

A boiler filling loop is an incredibly useful tool that is installed during a new boiler installation.

The filling loop provides a temporary connection between the boiler and the mains water supply so that you’re able to re-pressurise and fill your boiler with water.

If your boiler pressure has dropped below the recommended bar, you will need need use the boiler filling loop to top up the pressure to ensure your boiler operates as it should. 

Things to take away from this article

Remember, if you’re uncomfortable with re-pressurising your boiler, always call a boiler service engineer will be happy to advice or will even do it for you.

Don’t overfill your boiler otherwise you will flood it, this will cause a lot of damage.

Check your boiler manual to find out where your filling loop could be and what the recommended pressure should be.

THS Plumbing & Heating Northampton

3 Sunningdale Close



Tel: 01604 212732

Open: Monday-Sunday 7:30am - 10:00pm