Vokera 80SP boiler.Heating has to be on to get hot water

[Ashton]

To get hot water i have to turn the central heating on as just turning the water on does nothing.
This fault happened last year and the engineer fitted a new diaphram which worked for a couple of months then the old problem occured again.
I have been told it may be the thermal switch but am not sure.
With money being tight i can't afford to just throw money at it and would be grateful if it may be something i can fix myself???

 

[nickso]

most likely the diaphragm again. easy way to test is turn on hot tap and observe movement of fulcrum arm, if it doesnt move enough to hit the microswitch then its the diaphragm.