Thanks for the reply, this is what i've done so far. On the three way manifold I've removed both plungers that activate the micro switches as they were a bit stiff, so cleaned them up so they now operate smoothly & replaced the diaphragm. the microswitch that opereates first when dhw is demanded seems a little stiff in its operation so I'll replace that too. Do you know where the outlet filter is situated? Once cleaned and if the fault still exists whats next to look at in your opinion? Just a reminder of whats what, its a Vokera maxim 24e that will only fire up the boiler (when hot water needed as ch is ok) when the tap for dhw is on or very near to full blast.
Regards
Steve, October 2012
