DIY Doctor

Low Pressure

Postby thebungalow » Wed Dec 03, 2008 9:43 am

just had a new boiler fitted + one of those red expansion tanks both fitted downstairs in a small utility room. The problem is after a couple of hours i have "0-0.5" pressure on the gauge and i was told by my installer that if that happens to turn the inline tap on and refill the red tank till the pressure gets to "1.5-2.0". after a couple of hours it drops again to "0-0.5". i am doing this 3-4 times a day? i have spoken to the installer and he says there must be a leak somewhere. although there are no water traces anywhere? any ideas ? :?:
Last edited by thebungalow on Thu Dec 11, 2008 9:36 am, edited 1 time in total.
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Simply Build It

Postby plumbbob » Wed Dec 03, 2008 11:00 pm

Water is escaping from the system that's for certain. If it is not leaking by the pressure relief valve (check outside where the pipe appears) or through a faulty heat exchanger (unlikely in a new boiler) then the only other place is from somewhere else in the heating pipework.

Do any of the pipes run under downstairs floors?
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Postby thebungalow » Thu Dec 11, 2008 9:35 am

We do have floorboards in the 2 rooms at the front of the house. there is obviouslt a cavity of some sorts under there. is there any other way of finding where the leak could be or do we have to take carpets and floorboards up?
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Postby Steve the gas » Thu Dec 11, 2008 3:16 pm


Yep carpet + floorboards but try a small section (hatch) you might be surprised by the room under there or NOT
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Postby Low Pressure » Wed Dec 17, 2008 9:41 pm

I have that very same problem. I cannot get any sort of decent pressure in the system. I have searched for any possible leaks and cannot locate any.

Is it possible that the diaphram in the boiler is worn out?

I would love to get someone to look at it, but there are so many dodgy cowboys out there, investigations like this are best done by someone you can trust.

e.g. when my heat exchanger went last year, the 'expert' from Bord Gais told me that mains pressure is 20-25 bar... mad stuff....
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