Combi Pressure problem

Feb 03, 2012 8 Replies

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John 14 years ago

My aging father has a common combi (5yr + Vaillant /3 bed semi)pressure issue.

It all starts when he complains the rads need bleeding, dutiful son bleeds rads, reset pressure and feels smug until I notice pressure is too high. I reset the pressure, it now swings from 0.8 cold to 2.0 hot (just in the green zone) and suggest he calls in an engineer. The engineer does a service and says ?the pressure is ok if it stays in the green zone?.

All?s well for a couple of months and then the call came ? boiler won?t start, there?s no pressure.

I reset the pressure to min (0.8 cold) and strike it up, only this time pressure rises to 2.5 bar ? suggest he calls in engineer who (despite an explanation)infers some idiot has put in too much water and drains some out of the hot system.

Next day, see above except engineer has lost interest and suggests we call someone else!

Engineer #2 advises ?it?s ok as long as the pressure doesn?t rise above

3.0 bar?.

Am I the only one who thinks the EV or something else may be faulty or do you think this is good advice?

TIA, John

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Tim Downie 14 years ago

The "engineer" is an idiot. Classic expansion vessel problem. Either needs repressurising or replacement, depending on the fault.

Tim

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gremlin_95 14 years ago

Check the EV and re-pressurise it if it's not leaking. What model Vaillant is it?

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John Rumm 14 years ago

See the section here on expansion vessels:

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Roger Mills 14 years ago

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John 14 years ago

Thanks for all the feedback, the model is a Turbomax plus circa May 2005 ? but I don?t intent to take the case off in this weather, I get the blame for most things that go wrong already!

It?s just a case of finding a competent person to test it then. Shouldn?t have thought it would be THAT difficult.

John

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John Rumm 14 years ago

If you need a quick fix for the moment, isolate a rad at both ends, open the bleed screw and then slacken a union nut at the bottom to drain out a few litres of water. Then tighten the bleeds screw, and the union nut, and reopen the taps.

That will leave a pocket of air at the top of the rad which will act as an expansion vessel until you can get it fixed properly.

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Him & Her 14 years ago

John, what postcode area is your father in (e.g SE25) Someone may be able to recommend an engineer.

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John 14 years ago

Many thanks for the offer - After much research, I did managed to find a Vaillant engineer who spotted the problem and seems to have dealt with it without prompting! Relative peace has now descended on the old folks home, at least until we get his bill ? which I guess he?s still calculating.

John

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