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Fixing a stuck Worcester 24CDi/28CDi/35Cdi boiler refill valve

Postby McKendrigo » Sun Dec 19, 2021 7:34 pm

Hi, I've just moved into a new home and I've been trying to sort out an issue with the central heating. It seems there is lots of air trapped in the sealed heating system (radiators cold at the top, <1 bar pressure reading on the boiler gauge). I've tried refilling the system with more water, but with no luck - I think one of the knobs to do this might be stuck/jammed.

It's a Worcester 24CDi/28CDi/35Cdi combi boiler. The manual says to insert the "filling key" into bottom of the boiler and turn it to lock it in place, and then to turn a grey knob to allow water ingress.

The filling key was already inserted into the boiler when I looked, and seems to be possibly stuck in place (maybe there's a knack to getting it out, but I don't want to put too much force on the plastic). When I turn it, it just seems to turn freely, it doesn't stop in a particular position.

The grey knob also seems pretty stuck. There's a little plastic knob to turn the metal valve. The plastic knob turns, but I don't think it's actually turning the valve, which feels very stiff.

I'm at the point where I'd probably call someone out to take a look at it, and while they're at it, give the boiler a check over. Unless anyone has any suggestions? All I can think of is squirting some WD40 on the valve, when I dig it out of storage.

Photo is attached - the fill key is the white plastic T-shaped key, the other valve is the grey knob to the right of it.

IMG_2021-12-19-12-20-44-230 (1).jpg
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