Bought a house and the boiler keeps losing pressure

HouseBuyer77

One thing you can do is identify the outlet pipe from the over pressure valve (PRV, it lets pressure out of the system if it gets too high, sometimes they break or get stuck open). It will be coming out of your boiler and go through the wall, on the other side of the wall it will just be an open ended pipe. See if you can identify any moisture around it. Stick a bag over the end and leave it for a few days. If it's filling up you've found your leak.

You can also use the isolation valves for the central heating circuit to isolate the radiator system from the boiler itself. If with the boiler isolated pressure is dropping the problem is in the boiler, if it's staying stable it's a radiator or a pipe. Of course to do this you need to leave the boiler off for an extended period, so not ideal at this time of year.

CLAPTON

you can buy some sealent from any DIY, plumbing shop for about £20
you just pour it in.


it worked OK for me from having to top up once every month to once a year

HouseBuyer77

That stuff can also block up more modern heat exchangers, use with caution!