when the boiler is on it loses about 1/2 bar pressure say over 12 hours, when the boiler is switched off manually the pressure drops to nil, when we go to switch it on it goes into lockout until the pressure is reset.we dont think the timer works so we switch it on and off manually

has anybody got any ideas why the boiler loses pressure ????

LUKEWARMSUE, February 2011

There might be a leak on the system this is normally the reason for pressure drop.
If you bleed a radiator the pressure will drop.Check for leaks around the radiator valves or any joints/unions .

Might also be a fault on the pressure vessel itself

M, February 2011