Is the pressure gauge showing 1bar or 3bar+?
Are you constantly topping up the pressure?
If its staying about 1bar you probably just need to replace the PRV.
If its staying around 3bar all the time this could be the calorifier is pin holed and needs replacing, or an external filling loop is passing(unlikely cos the cdi has an internal loop and key)
If the pressure rises to 3bar when the heating is on this will be the expansion vessel needs recharging. To do this, empty the boiler of pressure via one of the white drain plugs under the boiler and pump up the expansion vessel to roughly 0.75 bar with a normal tyre pump whilst the drain plug is still open...close the drain plug and refill the boiler to 1bar. Hope this helps
gasmanjim, August 2010
