I have the same problem with my Puma 80 combi. System pressure at about half a bar when switched off then goes up and up the more rads I put on ending in the red. Prev thread says its the pressure vessel. Is this a big job? It will be repaired by a proper plumber of course!

bob, December 2007

depends! if you have a new expansion vessell fitted behind the boiler then yes i think its a big job, because from what a remember you require the boiler pretty much removing from the wall to replace the vessell, the easier option is to have a new vessell fitted somewhere else, only problem with that is its a little bigger than a football but shouldn't take half as much time! hope this helps!

kev!, December 2007