when resting and heating the hot water the pressure is about 1 bar but when the heating comes on the pressure goes to 3 bar.Switch the heating off and the pressure drops to 1 bar.Any ideas anyone.Thanks.

R>Whitington, July 2009

it could be your expansion vessel that has split or requires recharging. heat exchanger is blocked or there is an hose connecting the expansion vessel to the pump block. these can become blocked but the hose can be cleaned by using a long thin screw driver to rod it. if u dont know how to check reply back and ill give u some info

Nathan, July 2009