Have been working on a Ravenheat CSI 85 combi-condensing problem is on DHW boiler fires up for about 5 seconds then turns off repeating this I have carried out the following checks thermistors getting 12-15k ,found diverter valve passing,condense trap clear,min & max burner pressures ok, working pressure at gas metre is ok not sure if problem is plate to plate heat exchanger or does this have any pots on Pcb that may need adjusting would appreciate your thoughts.
Ps boiler fine on central heating
Thanx
Ps boiler fine on central heating
Thanx