by thegasman »
Sat Feb 27, 2010 9:33 pm
could be a couple of things, firstly you need to remove the cover and see if it runs properly-ONLY do this if Qualified to do so- if it runs ok then it is likely that the fan venturis are dirty and need cleaning out, if it still doesnt run properly we need to establish whether or not the hot water demand is constant or not if it is then its either a plate heat exchanger or thermistor problem if the demand is dropping out it could just be a diaphragm or microswitch-more info needed really to be sure