Boiler doesnt turns on and off erratically

alex d

Hi all,

I am a complete novice to heating, but recently my flat is always cold as the boiler will come on for say 1/2 hour, then stay off for hours before coming on again.

When its actually on, the flat gets very warm very quickly.

Its a closed system (no loft or attic, and no open tanks). The pilot light is lit, all radiators are bled, the thermostat works fine as when the boiler is on if you turn the thermostat it clicks and immediately turns the boiler on or off. But when the boiler is 'not working' the thermostat has no effect.

There is a pressure gauge on the boiler, and I topped it up recently as i thought it was low, but the pressure is all over the place, between 0.5 and 3.5 bar depending when i look at it.

any suggestions at all would be much appreciated!!

alex