Hi all, I have a wallstar combi oil fired boiler. We got low on oil a couple of weeks ago but didn't run out. Since we've had our oil delivered the boiler won't fire up when hot taps are turned on so no hot water. The boiler fires up periodically to heat water but not when we turn on taps. I haven't tried the heating yet as it's been too hot. When I put the switch on the external mounted part of the boiler to 'test' the heating and hot water work fine. Any advice would be much appreciated.