i charge the system to 1.5 bar, when the thermostate call for heat the pressure increases to just under 3 bar. as long as the tempiture stays the same it will hold the pressure in the system. as soon as you turn the temp down , i loss all pressure and have to top up again. Iv changed the preesure relive valve, made no differents.

paul edwards, March 2008

Ckeck the expansion vessel on rear of boiler, should be charged to approx 0.5 to 1 bar pressure (air) use a car tyre foot pump with gauge, you will need to do this with boiler drained and drain plug removed, or you will get false reading from xp vessel. If you get water out of tyre valve on xp vessel then it' s burst and it will require replacing. Also ensure the filling loop is disconnected after use this may cause over pressurizing if passing!

Belly, March 2008