"Dave" wrote in message
...
Nearly a year ago I changed the old vented system to a sealed one, whilst
also adding new rads and splitting it into zones. It all works well BUT
the pressure falls VERY slowly, probably from 1 bar to 0.7 bar over about
6 weeks.
I can't find any dampness around the rad valves or visible joints so have
resigned myself to waiting for the leak to get worse before I can find it.
Are there any suggestions on how to find the leak, or for anything I can
add to seal the leak (probably not a good idea)?

The GlowWorm book suggests a minimum pressure of 1 bar, is this just to
stop local boiling in the heat exchanger?

Dave

I take it you've got a pressure relief valve vented safely to the outside?
Is this pipe dripping?

Alternitavely, I take it you've installed an expansion vessel into the
system - has this got the correct charge (Around 0.7 bar cold)?

Angus

Angus