On the boilers first ignition it stays on for some time, and then when the return water to the boiler is hot it shuts off, but the room temp is still below the desired setting (set at 20c at the moment), it then is on and off for the 55 seconds every time. I believe this is because the room...
Andy - Have checked vent and feed pipe....both clear.
D_Hailsham - No TRVs all lockshields, when the boiler was serviced the thermostat was checked and found to be ok. Re the pump, I took the large screw out and stuck my screwdriver in to test the speed the impeller was working, it was quick.
Really hope someone can help as I can't afford to tear any more hair out!
The problem
Boiler cuts out and comes back on every 55 seconds
4 (out of 8 ) downstairs rads are lukewarm at best
The situation
Large house with 16 rads, 8 upstairs 8 downstairs. System is about 25 years old...