by stuartcmorrison »
Fri Apr 02, 2010 6:47 pm
other advice pointed me in the direction of the flow valve where i would probably find a perforated diaphragm.
removed and dismantled said flow valve only to find there is no diaphragm, the flow valve doesn't look like the one in the diagram but is wired into the same flow terminals, i'm assuming this is an improved design as it seems diaphragms were a common problem.
on this one there is just a pendulum which swings up with water flow and then activates the hot water (don't know exactly how the activation works as there is no metalic contact and doesn't seem to be a micro switch). anyway, by powering up the boiler with this flow valve in my hand i turned it upside down (to move the pendulum) and hey presto it calls for hot water.
assembled everything back together and it all works as it should (for now), i can only assume that maybe the spindle on the flow valve was sticking slightly and through man handling it's freed up.
anyway, i know where to look next time.