When we turn on our combi boiler, some of our radiators go on as well. When we have the 'summer' setting on (hot water only), the boiler won't light at all. Does this need fixing or is there something we've missed?
As per your other question you have not mentioned the make or model of boiler and different boilers operate in different ways. Normally the boiler on water only will only fire up when you turn on a tap(see your other question for preheat) and if it is not doing so then there is a problem with the boiler. It is impossible to give a definitive reason what without the required make model of boiler due to the differing operating systems between different makes and models.
