Saturday, 15 January 2011

What to do if your boiler loses pressure

 Today my boiler broke. Ok that’s a slight exaggeration but the red light came on and the heating and hot water went off, so to me it was broken. After the initial girly panic that comes with a machine breaking I set about looking for the reason. The gas hobs were still working so it wasn’t a problem with the gas supply (this has happened to me before with some kids turning off the gas supply to my flat!).  A check of the pressure gauge showed the pressue had dropped below zero bar. I knew that was bad news and that I needed to increase the pressure, but that is where the knowledge ended. I didn’t want to call a plumber out on a weekend for such a minor thing so I turned to the trusty internet to find out how to do it but I couldn’t find exactly what I was looking for. In the end I phoned my dad (thank God for dads!) e-mailed him a photo of the pipework and he talked me through it step by step.

The result – boiler back up in and running in 5 minutes and this simple step by step guide for anyone who wants to know how to increase boiler pressure.

A Girl’s Guide to Re-Pressurising Your Boiler

Step 1 – If your pressure drops it could be due to a leak form the boiler itself or form a radiator, so the first step is to check for leaks.(if you do find a leak then you probably are going to need a plumber)

Step 2 – Identify the water pressure taps. These are located at each end of the silver braided pipe and are usually black.  In the picture below you can see a circular tap on the left just below the clear pipe and on the right its a rectangular tap which sits in line with the 2nd pipe that runs vertically up into the boiler.  (important note: there is a black stopcock higher up on the right – this is not the water pressure tap!) 

Step 3 – Open the tap on the left by turning it 90 degrees anti clockwise, this opens the pipe.

Step 4 – The tap on the right is more like a lever, push this to the left and you will hear the water begin to flow through. (this lever can be quite stiff so you might need to apply strong pressure to open it)

Step 5 – The pressure will start to increase on the pressure gauge, when it reaches 1 bar turn the taps back to their original positions, the lever shaped one first.

Step 6  - Turn the dial on the front boiler panel to the off/reset position and you will hear the boiler re-ignite and the green light will come back on.

Step 7 – Turn the dial back to hot water/heating option and voila you’ve fixed your first boiler!

When you’ve done this you might want to bleed your radiators to make sure you don’t have any airlocks in the system.

These instructions are based on a Vokera combi boiler, please let me know if you find them useful! 


  1. Thank you!Thank you!Thank you!
    I got the same problems today...
    Finally, my boiler is working again!

    1. I'm so glad you found this useful, really pleased i've been able to help someone avoid the trauma of no heating or hot water in winter! Thanks so much for commenting. Apologies the reply is so delayed.