Hi and thanks for your response, I’m sure the pump (Granfos) is running and the boiler stat is on full. I have a spare pump as this one is set on position 3 as it makes a noise when set on position 2, could that be the answer then?
Help I have just moved into a new house that has a Glow-worm Fuel Saver 80 F. the boiler lights up fine and then runs for about 30 – 40 seconds and then shuts down for about 30-40 seconds and continues like this, any ideas?