Baxi 105e water preheat

[fd54]

The preheat feature on our Baxi 105e boiler doesn't seem to be working. If I turn the thermostat down and up again it seems to activate it but you have to do this each time you want the hot water to fire up and even when it does the water heating light continues to flash and never resolves to a solid continuous light so the water starts to lose heat again.

Anyone any idea what is happening and how to fix it?

thanks a lot.

 

[gas112]

The water will only preheat it wont give you continious hot water when drawn .
When you turn tap on the light should turn to a constant one if it doesnt then the diaphragm is probably kaput and not moving the pin into microswitch to activate hw demand