I HAVE A SIME 80C FORMAT COMBI BOILER. THE BOILER DOESN'T IGNITE WHEN RUNNING WATER SO I GET NO HOT WATER AND THE ONLY WAY I SEEM TO GET WARM WATER IS BY PUTTING THE HEATING ON BUT AFTER A WHILE THE FLAMES GO OUT AND JUST THE PUMPS RUN.. VERY STRANGE AND FRUSTRATING. ANY IDEAS PLEASE