I have a Potterton boiler and Honeywell 'S' plan system.
I just replaced one of the valves because it had stopped operating.
Now, when the timer clicks in, valves open and pump starts, but the boiler does not fire up for about 1 hr even when pilot light is on. (Separate long time problem, sometimes the pilot light takes 10 minutes of 'sparking' to light the pilot).
Please can you advise.