Ventilation fan works fine when heating is off but immediately switches off when heating is turned on. Consequently the furnace runs for a minute and then overheats and turns off.
Any idea what could be the cause?
When switch furnace on, ventilation fan turns off
central-heatingfansfurnace
Best Answer
Many thanks to all who have attempted to help. I am afraid the question was based on my mis-interpretation of the symptoms. In fact the furnace was attempting to light, but failing due to an exhaust problem (now fixed) -sorry! Martin