Boiler pressure keeps dropping

Liam Pike · 10 Nov 2018

Hi,

The pressure in my boiler keeps dropping. I've had to repressurise once or twice a day for the past few days. Obviously this isn't right so I'm looking for advice on what the issue could be.

The boiler itself is new and was only installed around 6 months ago so I don't think it is that. It is under warranty so I'll be getting an engineer out to take a look at it.

I previously had a burst heating pipe under my flooring that was repaired in the last few months. I'll be taking this flooring up to see if that join is solid. My worry is finding the leak if it is not under that flooring as I've recently had both my bathroom and kitchen floors tiled and ripping these up will cause considerable damage.

Are there any ways to find the leak without ripping up loads of flooring? I've read a little about companies that use thermal imaging and other techniques. Are these effective?

Thanks
Liam

terryplumb · 10 Nov 2018

When central heating is on ,does your boiler pressure ever rise to around 3 bar ?

Liam Pike · 10 Nov 2018

terryplumb said:
When central heating is on ,does your boiler pressure ever rise to around 3 bar ?

Hi mate. It doesn't, no. Sits somewhere between 1 and 2 usually.

terryplumb · 10 Nov 2018

Then its most likely a leak on your pipework / radiators or valves. You said you had a " burst" heating pipe ,is your new boiler a combi ,and was it a replacement for a combi or did you have other work carried out to change from a gravity system ?

Liam Pike · 10 Nov 2018

terryplumb said:
Then its most likely a leak on your pipework / radiators or valves. You said you had a " burst" heating pipe ,is your new boiler a combi ,and was it a replacement for a combi or did you have other work carried out to change from a gravity system ?

It's a combi boiler replacing an older combi, yes. That was the only work I had done. After changing it over I found a leak in one the pipes under my floor and had that repaired. Is it worth me checking all the valves on my radiators as a first port of call do you think then?

terryplumb · 10 Nov 2018

Check all visible pipes ,rads valves and their air bleed screw's and the blank cap ( opposite end to bleed valve ,top of rad ).

Liam Pike · 10 Nov 2018

Thanks mate. I'll check all that asap. If I can't see any issues there do you think it'll likely be somewhere along the heating pipe under the floor?

terryplumb · 10 Nov 2018

Also check outside ,copper pipe from boiler pressure relief. See if any water dripping from it.( shouldnt be ). And of course leaks around boiler itself. Also signs of discolouration on ceilings ( leaks from above) When all these possibilities are ruled out then suspect pipes that you cant see.

mcmoby69 · 10 Nov 2018

Re pressurise the system. Turn off boiler Isolate flow and return under the boiler. Wait 24hrs, if pressure is ok on boiler it's not that, if pressure drops when you open iso valves, the leak is on your system.

A few minor weeps that evaporate can also be a cause.

Liam Pike · 19 Nov 2018

terryplumb said:
Also check outside ,copper pipe from boiler pressure relief. See if any water dripping from it.( shouldnt be ). And of course leaks around boiler itself. Also signs of discolouration on ceilings ( leaks from above) When all these possibilities are ruled out then suspect pipes that you cant see.

Just an update. I’ve checked all visable pipework and even ripped up the floor in my hallway to try and find a leak. Nothing visible there. I always checked the boiler pipework and the pressure relief. Nothing there either. I’ve had an engineer come in to take a look at the boiler and he couldn’t see anything wrong there.

The only floors I haven’t taken up yet are newly tiled so I don’t really want to take them up unless I really have to. I’ve seen a few different heating sealant products that you put into your system which are supposed to seal leaks. Are they effective in your experience?

Thanks again.

terryplumb · 19 Nov 2018

Never used " leak sealing" chemicals ,and dont like the idea to be frank ,i take the view that its better to sort out the leak.
Have you tried isolating the boiler ,as mcmoby suggested ? If you are still topping up the boiler twice a day and have been doing so for weeks , one would expect to see some evidence of the escaping water and i would not start ripping up tiled floors just yet. Its a possibility that your boiler heat exchanger has a pin hole leak and water is being evacuated from the condensate pipework ,which is not easily noticed. I would do as mcmoby advised to rule this out.

gasmanstu72 · 19 Nov 2018

is your bathroom upstairs?
if it is, then i would've thought that any leak under that floor would be visible on the ceiling below (which might be another way to look - take the ceiling down rather than the floor up)

HERTS P&D · 19 Nov 2018

My guess would be a leak on the ground floor, you could hire a thermal imaging camera and find the leak.

Andy

Madrab · 19 Nov 2018

was the central heating system existing and did the previous boiler have a small black tank in the attic?

ianmcd · 20 Nov 2018

if it is a new boiler it will be a condensing boiler, with the boiler turned off remove the condensate pipe and leave it for about an hour and see if you get any water from the pipe, if you do it is probably the heat exchanger has failed, will be under warranty though so if it is that you should be covered, what make and model of boiler do you have

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Boiler pressure keeps dropping

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