Good Morning,

I have a Potterton Puma 80 boiler connected to my central heating. When the heating is off the pressure is just over 1 bar. About 20 mins after the heating comes on the pressure goes to over 4 bar at which point I switch it off as I'm scared damage will occur. Once the heating is switched off the pressure goes back to just over 1. Has anyone any ideas what may be the problem ? Any suggestions would be gratefully accepted.

Coupleojars, November 2005

yes the pressure vessel is faulty this takes up system pressure when hot you can replace the one on the boiler or fit a remote one , check the safty dischage out side if this is dripping the prv needs replacing

RAY, April 2007

1st thing is to check is the expansion vessell behind the boiler it sounds like it needs recharging you will need to drain the system and recharge via a footpump on the connection on top of the expansion vessel it needs to be pumped to 1bar but when pumping it the system needs to be open(keeping the drain point open)

d.., November 2005