"Christian McArdle" wrote in message
. net...
Last time I found the expansion vessel wasn't doing its job, I managed
to pump 10psi of air into it, and it then worked perfectly for a few
months until this latest event.

I would replace the vessel. It should not require regular precharging.

Well not regularly but you do come across the customer who says I had such
and such wrong and I thought I'd check for airlocks. I let a lot of air out
of here but it still won't go g

Christian.