In message .com,
Graham writes
Ok well i checked the micro switch opreation .. and it functions fine
with low/medium hot water flow ..hot water supply is fine - 100 p/c ...

flame control module, well i mean the cct for the whole control box -
there are a few boards in there ..

it must be something that the direct hot water over-rides as once you
have run the hot water .. dam thing works fine again ..

also a slight tap on the box has the same affect .heating come back on
. hence i think its a joint on one of the boards ... but which one ..

when it clears .. you can here the relay 'click' in the control box
prior to the gas opeing .. so what drives the relay ?

Top board - fl sup board
bottom board - fan ctrl board

neither are interested in what mode it's in

it's either the motherboard or the thermostatic board - the middle one
.... if that is indeed the problem

--
geoff