I have a 13 year old Vaillant combi boiler and the heating works but it's not heating the water, so I have no hot water. I can't find the details now and there is nothing on the boiler to tell me what model it is, how can I find out as I need a new pump to fix it, but apparently there were a few made at the time? can you help me to know what it could be?

Sam, February 2009