hi all, i just want a bit of advice, i have a icos he15 boiler that has started to make banging noised when started, the panel all lights up as it should be after a few minutes it starts to bang and the burner light starts to flash this will countiue to cycle like this if allowed, i have noitced the pump in airing cupboard is lighting up power but nothing else where before i know this whould light up three bars, so i was just wondering if anyone could tell me if this sounds like a failed pump thanks