Paging anyone who knows a bit about plumbing here as I can’t raise a plumber to come out..

Noticed the water pressure was down on the heating system so tried to pressurise it as the plumber has shown me before and I’ve done many times before.

The pressure gauge – set to 1.5 bar is on top of a big red expansion vessel – maybe 5L in size. The water taps and pipework feed into the vessel so normally re-pressurising the system causes the pressure gauge to move and there’s a sound of water moving through the pipework.

Tonight though, quite a bit of extra water temporarily raised the pressure but the air valve at the bottom started to hiss and the vessel feels like it’s very full when I tap it. As it’s not fitted to particularly strong brackets I don’t want to risk adding any more pressure / water in case it falls off. I’ve tapped the gauge to make sure it’s not stuck but it’s now back at 0 bar even though I’ve added quite a bit of water…

Any ideas?

1 of two things.

The vessels lost pressure and you just filled it with water

2 the bladders ruptured and you just filled it with pressure .

Locate the scraeder valve and depress it- if you get more thn a few drops of water – new vessel required

If you dont get anything or a little air you need to charge it back up to 1 bar when cold – but you also need to release all that extra water you just put into aystem.

If you dont do this , next time your system fires and doesnt have anywhere to expand to your prv will blow and your system will drain.

Thanks trail rat – air seems to be coming from the bottom of the vessel but not through the core or the shraeder valve – have turned the system off so looks like even more expense – the vessel is only 14 months old and the system has been a king size pain in the derrière since we moved in.

I had a combi in the old house which lost pressure regularly (the pressure vessel was a flat internal thing rather than that gas bottle looky-likey you’ve got) and magically the system stopped losing pressure when a (good) plumber came along and re-pressurised it – with my track pump (not the filling loop).
Worth a try Shirley?

FWIW water will slowly absorb air which is why there is a bladder in there, and why my homebrew pipe-hammer arresters need draining every now and again.