1. when I attach a pump to put air into the vessel, having got it to the correct 1 bar pressure on the pump, the air is released with the removal of the pump (it can be heard escaping...). I have replaced the Schrader valve in the expansion vessel and this still occurs ....
2. on this boiler (Saunier Duval SD 620F) the expansion vessel comes off the mains inlet circuit - can this be correct???
Thank You

Martin, January 2010

Thanks again Wirecutterman I have done that. what type of guage do you use to measure the air pressure in the expansion vessel? As when I do it a lot escapes when Im removing the pump...
Regarding the PRV - is it at the top of the CH `flow circuit pipe from the boiler and look like it would have a horizontal pin/bar through the connector ??want to test that bad boy and make sure its working too...
The pressure is now at 3bars with the heat on about 70 - 80 degrees ... still seems a little high ?? Thanks

Martin, January 2010

if you can hear it leaking ,remove valve core inner and replace it,i ve swapped out 5 before i found a good one ensure that the seating by the spring is SPOTLESS
this little area keeps the air in, (including your car tyres inflated) ensure valve core inner is tight use tool or fine long nosed pliers.
do the spit test to see if leaking like you test a bike valve,
(I do any way)

wirecutterman, January 2010