BAXI 105 HE No hot water

[Sparky1971]

Hope someone can help,

I have a BAXI 105HE, which has stopped giving hot water on demand, heating works fine however when we call for hot water we have to open 2 or 3 taps before the boiler will give a green light for the DHW on the front of the boiler. Sometimes even with a few taps open it wont give DHW - although a sharp knock with a screw driver on the valve assembly ushually works, there has been a couple of times when we have not been able to get hot water at all. This seems to be getting steadily worse. Any help would be appreciated

 

[buckley plumb]

probably the hw pressure differential diaphragm.about £8 from merchants.

 

[Sparky1971]

Is there anyway of proving this, against for instance, a sticking 3 way valve?

 

[buckley plumb]

on front of valve assy is a micro sw remove this then run a hot tap the spindle should move out . if not turn off cold to boiler and drain from a hot tap remove front of diapraghm unit and check for splits in the rubber diapraghm.if it was diverter on hw demand the heating flow would get hot