hi calum. if you drop the front panel (two screws above digital display) on the L/H side youl see the pressure releif valve (black plastic cylinder with a red tip and small lever attatched to a brass pin) press this towards the wall and observe the gauge until it goes down to 1.5 bar. If the pressure builds back up the likelyhood is you will need to replace the expansion vessel. The boiler will function safely at 2.5 bar and is fitted with an automatic blow off valve which will automatically release the pressure if it reaches 3.0 bar. Hope this helps Jim H
Jim H, February 2006
