biasi 24 S boiler 'not gettting any hot water' Advice needed

[shirl1]

Hi,
Could be duplicating my post here, not sure if last one got posted but i'll send it again anyway.(I'm new )

I have a Biasi boiler model S 24 which has suddenly stopped heating my water.
Central heating is working ok and I can only get hot water at moment if I switch heating on at the same time.
Any suggestions/advice on parts etc. would be appreciated.

 

[ANDYSI]

I had exactly the same problem, I had 4 engineers look at it they changed 3 way diverter valve twice and replace diagphram, but still same problem. I decided to turn the water pressure up slightly at mains stop cock. I haven't failed to get hot water since. I think there wasn't enough pressure to push diaghpram which then pushes hot water ignition micro switch. hope this helps.