Vaillant combi boiler vcw gb 221 h

19 Jan 2005
Reaction score
United Kingdom
:?: VCW GB 221 H :?: Could somebody please give me some advise on my boiler, which has broken down? Or is there anybody with the service manual to this one? The hot water is still running luckily. However, the pressure is dropping constantly and the CH won't start up. Sometimes when I switch it of and do not touch it for a night, it works again for a little while in the morning but then it switches off again after half an hour. :?:
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Cheers for responding!
No wet patch on the wall. The overspill pipe is mounted underneath and I've placed a bucket underneath because sometimes it leaked a bit when I filled it up.
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Dunno what prv is but when you add water to system and it becomes higher then 2 bar it throughs it out automatically. Seems to be some kind of safety valve :rolleyes:
it is a saftey valve and it should be connected to outside and pointing down

fill to 1 bar run the system and watch the gauge

prv Pressure Release Valve

you are either losing it from there or you have a leak
In that case I probably have a leak but I can't see where, The prv is fitted inside. That's why I got a bucket underneath it just in case.
When the pressure is 1 bar and I switch on the CH it goes up a little bit but then aftwer a little while it just switches off and it won't switch on again. It seems that also after I haven't used the hot water it works again for a little while :?: :?: :?:
Any more ideas. Or would anybody know where I can get the service manual from :?:

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