# gas boiler losing pressure



## tabatha (9 Dec 2008)

i got a new gas boiler put in about just over 2 months ago.  since i got it put in it has been lossing pressure very slowly.  i have topped it up three times so far.  i cant see a leak anywhere.  the company who fitted it came back and did a check of all the pipe work downstair and found no leak.  there are no marks on the ceiling upstairs so dont think its from there (cant check either as all laminate flooring upstairs).  the overflow pipe outside is dry so not that either.  it is going from being on 1.5 bars (when heating is off) say 5 weeks ago to now being on .8 of a bar.  is this normal?  when the heating is turned on it goes back up to about 1 - 1.2 bar but when off drops again.  i was told that there is probably a very small leak somewhere but my issue is that i dont want to keep having to top my system up cause from what im reading on here its bad.    any ideas of what i can do?  the company who fitted it dont seem to care!


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## BD plumbing (10 Dec 2008)

*Re: gas boiler lossing pressure*

hi you can but in a soloution called sentanel leaksealer for heating systems this job can be awkward to put in on sealed systems but it should do the trick as it will stop any small leaks a weeps


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## tabatha (10 Dec 2008)

*Re: gas boiler lossing pressure*

i used a stuff years ago for a small leak i had under my bedroom floor called fernox i think.  does this stuff not dirty your system though and harm the condenser boiler?


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## grahamo (10 Dec 2008)

*Re: gas boiler lossing pressure*

I had the same problem a few years back. couldn't find a leak anywhere in the house. I took the cover off the boiler to check and found the insulation around the heat exchanger was damp. turned out to be a pinhole leak in heat exchanger. Boiler manufacturer tried to tell me it was installers fault as they probably didn't add inhibitor to system. I told them hole was on the weld so weld was faulty and they replaced it as boiler was only about a year old and still under warranty.


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## tabatha (10 Dec 2008)

*Re: gas boiler lossing pressure*

i will get my husband to have a look at that tonight, thanks grahamo.  these new boilers seem to me more trouble than there worth!  im getting fed up looking at the pressure to make sure its ok.


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## DGOBS (13 Dec 2008)

*Re: gas boiler lossing pressure*

If you wish to leak check your entire boiler, then wait until you can bare to go without your heating for a few days (bit cold for it now) and then turn og both flow & returrn isolators under the boiler, check system pressure, check again in a few days, if it  has dropped, then you know 100% there is a leak in your boiler.

How much is your pressure dropping?

Pressure should only ever be checked when system is 100% cold and system pressure should be between 1 - 1.5 bar COLD, don't worry about what the pressure is when the sytem is running as long as it does not exceed 3bar


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## tabatha (15 Dec 2008)

thanks for that dgobs.  my system pressure when cold is under 1 bar, about .8 of a bar.  it was 1.5 bar about 4 weeks ago.  the leak must be very small for it to have dropped that much in 4 weeks.  cant find the leak anywhere.  we are away for a few days over the christmas so i will do what you said then.  can you tell me what and where these things i have to turn off are?  i have no knowledge of boilers or tanks!  thanks for all your help.  wish the guy who installed the system was as helpful!


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## sfag (15 Dec 2008)

I have the same problem. Mine is a glowworm boiler - what is yours. I have no apparent leak.


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## DGOBS (15 Dec 2008)

the flow and return isolation valves are underneath ur boiler, you'll see 
4 pipes, only with possibly a yellow handle (thats the gas) the other with no handle (thats your pressure release pipe) that leaves 2, flow and return....have a look through your boiler manual


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## tabatha (15 Dec 2008)

thanks once again.  mine is a baxi boiler sfag.  what pressure is yours and how much is it losing?


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## sfag (16 Dec 2008)

tabatha said:


> thanks once again. mine is a baxi boiler sfag. what pressure is yours and how much is it losing?


 
About 1 bar a week.


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## DGOBS (16 Dec 2008)

Adding fresh water week in week out to your heating system is going to distroy it


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## tabatha (16 Dec 2008)

DGOBS said:


> Adding fresh water week in week out to your heating system is going to distroy it


 
thats what im afraid of......mine doesnt lose that much sfag.  im lost 3/4 of a bar in 6 weeks.  my leak must be tiny.


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## noelf (18 Jan 2009)

Best thing is to try an internal leak sealer, but do get someone who know what thay are at, if you have had a new boiler fitted to an old system make sure they added the correct chems too. Many new boilers have alloy heat exchangers and they do not like dirty systems. Have a look at your rad  valves for discolouration around they heads of the valves. A system loosing the type of pressure you are talking about is a very minor weep.


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