Baxi boiler pressure dropping

[Thebeardedone]

Hi,
I would appreciate your help for an issue that has been going on for a month or so.
It is an old boiler that has worked well thus far.
Boiler: Baxi Megaflo system HE

I have had to top the boiler pressure up at least once a day. After topping it up to 1.5 or 2 bat the pressure will be down to 0 the next day. The boiler is still functioning and heating the radiators and hot water as normal even with low pressure.

There are no obvious leaks in the radiators and pipes I can see.

An engineer came out and replaced the expansion vessel as it was leaking, but the issue has persisted. He has come round today and advised he can not see an issue with the boiler and no obvious leak. He has advised we employ a specialist leak detector to help find the leak from the pipes.

I am sure that with such pressure loss that there would be an obvious leak point from the flooring by now.

I was hoping for advice to ensure that it is definitely not the boiler before going down the leak detection route.

I have read that switching off the boiler and isolating overnight may help determine if it is a boiler issue or not. If you think this would be useful your help in advice on how to do this would be much appreciated.

Thanks in advance

 

[cross thread]

Check the safety discharge pipe is not dripping
Leave boiler completely off and check the condensate pipe is not dripping .
First one would be pressure relief valve passing ,2 nd so be heat exchanger leaking ,after that system leak .
Careful check around all radiator valves

 

[jj4091]

Search results for query: baxi boiler losing pressure

www.diynot.com

 

[alterius]

If you have CH pipes that run under floors - particularly suspended floors at ground floor level - then you may be losing water from a joint that you can't easily get to. I would try and isolate the boiler first as you suggest, and see if the pressure is maintained in the CH system. If it is, then I'm afraid it points to the boiler being the culprit. You can only isolate the boiler if the necessary isolation valves have been built into the CH loop. They should be fairly obvious near the boiler on the flow/return CH pipework.

 

[Jurassicspark]

Has there been any recent modifications to the heating system?