Water runs hot (very hot) for a short time, then flame goes out. Few seconds later it fires up but then trips out (red LED). Managed to turn down temperature control dial to about half way, the water comes out HOT, but doesn't trip out. If I turn the temp up then it trips out again.

Sounds like it is overheating but why?

CrowDA, April 2006

Thanks Bob. Can you tell me which diphram you are refering to. Perhaps it is best I strip the lot!!!
I find that if I turn the temp down and then run the hot water slowly then it maintains.

Funny thing is that the central heating works fine.

CrowDA, April 2006

the diaphram is letting by (renew it)
and check the h/w/heat exchanger is not clogged up.
last one i did, I found sand and stones in it, from pipework not being protected during installation, the other problem is rust from your rads,causing flakes to block the h/w/exchanger

bob the plumb, April 2006