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Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3629
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
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Boiler loosing Pressure... So i've had two certified

Customer Question

Boiler loosing Pressure...
So i've had two certified plumbers and a British Gas engineer come out to try and figure out why my boiler is loosing pressure. We're loosing 1.5 bar of pressure at least twice a day when we top it up with the filling loop.
What we know so far.
We have check outside and there is no evidence of water coming from the pipes at the back of the boiler both when off and in use. no water marks on the outside wall etc
We have pulled up floors and double checked all ceilings for evidence of water leaks, and also in the cellar (its and old house). there is 0 sign of water coming from anywhere.
We suspect it might be a part in the boiler but for me it doesn't explain where the water is going!
This is really frustrating.
Submitted: 9 months ago.
Category: UK Plumbing
Expert:  Gaztech replied 9 months ago.

Welcome to Just Answer, my name is Luke

NOTE: I can only get credited for assisting you if you RATE ANSWER the 5 star rating

Are you ready?

Customer: replied 9 months ago.
No worries
Expert:  Gaztech replied 9 months ago.

I would isolate one zone at the time by shutting both valves until in notice a change in pressure loss.

And then isolate the boiler itself with in and out valves to determine if that is the issue.

Expert:  Gaztech replied 9 months ago.

NOTE: I can only get credited for assisting you if you click the 5 star rating

Customer: replied 9 months ago.
Hi sorry we actually did that. Isolated the boiler and the pressure held. As soon as we opened the valves again the pressure dropped
Expert:  Gaztech replied 9 months ago.

Did you isolate each zone at the time for one day each by shutting both valves until in notice a change in pressure loss.?

Customer: replied 9 months ago.
No I haven't isolated each individual radiator as I assumed if it was a leak of the quantity of water were losing it would be obvious? You'd see it coming from the radiator or at least on the floor/ceiling?
Expert:  Gaztech replied 9 months ago.

I realise that, but still a concealed section of pipe may be the problem and this would give you an idea of where to look.

Customer: replied 9 months ago.
OK I'll give it a go tomorrow but I honestly think that it's a waste of time. The plumbing goes straight down into the floor so I can see all the plumbing above the point I'm going to cut off.
Expert:  Gaztech replied 9 months ago.

I dont know what your structure looks like, just use common sense if you feel it does not apply.

Expert:  Gaztech replied 9 months ago.

I will opt out and let another expert try to help you.

Customer: replied 9 months ago.
Hi Gaz. OK so in my limited plumbing knowledge I really want to assure you that I think the leak is floor level except it's not where I thought it was after ripping up two floors. There is a stretch of piping from the boiler to first radiator in the circuit where there could be a leak.
Expert:  Andrew Smith replied 9 months ago.

Do you have any pipes in concrete?

Do you have a screwdriver?

Customer: replied 9 months ago.
No Just under wooden floors.Yes I have a screwdriver
Expert:  Andrew Smith replied 9 months ago.

You definitely have a leak on the system if the pressure holds when the boiler valves are off.

If you leave your filling loop cracked open and make sure it does not rise above 2 bar then you may find a damp patch.

Also if you do this and put a screwdriver against the pipework and the blunt end against your ear then you might be able to trace the whistle in the pipework to the leak.

Another way would be let the heating get red hot then do as above and see if you can follow the cold water to the leak as it makes the pipework cold.

Customer: replied 9 months ago.
Hi there, The leak is still a mystery! To confirm we shut of the in/out valves to isolate the central heating and the boiler held pressure, as soon as we released this the pressure dropped. Basically confirming we have a leak.I have taken up a couple of the ground floor flooring up and as far as i can see its bone dry, is there a special peice of kit I can hire that might be able to help me find where the water is going or where the leak is?Cheers
Anthony
Expert:  Andrew Smith replied 9 months ago.

Unless you can take up all your floorboards and check all areas?

There are companies out there that do this sort of service - leak detection

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