potterton prima F not firing up?

If the boiler fires up then there's very probably nothing wrong with the boiler - perhaps you should be suspicious of the timer programmer.

What happens if you select it to be permanently on and just use the room thermostat as a method of control - turn it down when you retire for the night and up again in the morning - same when people leave in the morning and return in the evening.

Good Luck...
December 2016