I have a "Glow Worm" combi boiler that has been losing pressure slowly - from 1.0 bar to 0.6 bar over the course of a few months.

The instructions simply say that to restore pressure, "slowly open the filling tap beneath the boiler to pressurise system to 1.0 bar. Ensure filling tap is then closed."

Being utterly hopeless with all things home-maintenance-related, I hope Stack Exchange can offer some advice! The underside of my boiler looks like this:

Boiler (Underneath)

The only thing that looks like it might be a "filling tap" is the blue blob in the middle near the top of the image. Close-up:

Filling Tap?

As far as I can tell, the blue bit on the end doesn't twist or pull off to reveal anything underneath - though as the instructions say "slowly" I haven't twisted very hard. The shiny band just above it turns with no resistance at all, and I don't think turning it is doing anything useful.

Can you offer any advice as to where I am going wrong? Is restoring pressure just a matter of turning the tap (when I find/manage it) on and off again?


I just googled the manual for the glow worm series of boilers and it look like you need to connect a flexible hose from the domestic water supply (far left if looking at front of boiler to the bottom of the thread under the blue cap, and then turn the domestic supply on. with out the model number of your boiler it is a bit hard to give you exact instructions. but the manual does say that the hose should be disconnected after pressuring which is why its probably not straight forward just looking at it. try this page glow worm manuals

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  • Thanks, I'm not sure how I failed to find that site! (Mine is a Glow worm 30cxi.) It looks like I do indeed need to manually make a connection from the domestic water supply, using a hose that I don't have! Looks like my first step will have to be to track down a hose with the right fittings to do the job. – Ian Renton Apr 18 '12 at 5:42
  • check out the 30cx plus manual on page 13 it show that item 20 is the filling system which may indicate that it has just a filler tap instead of a separate connection – UNECS Apr 18 '12 at 5:53

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