DIY Doctor

central heating combi boiler problem

Postby carter barter » Fri Dec 12, 2008 10:02 am

I have a Ideal C80FF combi boiler that is playing up. The problem is the presure keeps droping down to zero but when I presurise back up to 1Bar it runs ok but the preasure soon rises up to 3bar I then turn the heating off and it soon drops back down to 1Bar and below. Any Ideas?[/b]
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Simply Build It

Postby Steve the gas » Fri Dec 12, 2008 3:34 pm


Check the expansion vessel, it has a schrader valve,check pressure in it.
It should be 0.8 - 1 bar, diaphragm could have failed.
Don't be too worried about the 3 bar pressure the PRV will dump the water outside.

If this is worrying you - get an RGI in.

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Postby htg engineer » Sat Dec 13, 2008 10:08 am

As stg says - it'll be the expansion vessel at fault. Press the valve on the expansion vessel.

Air ? re-pressurise
Water ? the diaphragm is shot and you need a new vessel.

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