im assuming you dont get DHW
split DHW diaphragm is the most likely cause
split diaphragm cant push pin against DHW microswitch
its possible to change diaphragm with DHW flow valve in situ
buts its a pig of a job
much easier to remove DHW flow valve entirely
& change diaphragm
then replace DHW flow valve
i personally would also take this opportunity to replace internal working mechanisms of the divertor valve
the divertor pin has a tendency to buckle when DHW splits
a very fiddly job
unless you're super confident about tackling this
i'd leave this job for a professional
manwithnoname, May 2011
