Potterton performa 30HE no hot water

[Nas]

I've checked all the obvious the apart from the DHW temp sensor, can this cause the boiler no to fire when there is demand for hot water?

The Heating works ok and the DHW diaphragm is ok , the only thing I didnt check was the DHW water temp sensor. The Assuming the PCB is I can't think of any other fault that would cause the water not to work.
Also when the heating is on and the tap is opened the flame extinguishes as soon the DHW micro switch is pressed.

Thanks in advance

 

[diamondgas]

You'd usually get a light flashing on the front if the sensors out of kilter Nas .... However it's worth having one handy! Check that the hot water demand light is on too when the switch is made

 

[Nas]

The hot water demend light comes on ok. But there are no flashing lights at all to indicate any errors. The hot water water demand light comes on and the pump runs but the fan does not kick in. The PCB has been changed already I dont think its the PCB. Since heating works ok I'm assuming the APS and fan are OK.

 

[Billy Bob Bob]

i would not rule out the aps on the he, first signs of it failing are no dhw but heating working

 

[diamondgas]

The hot water demend light comes on ok. But there are no flashing lights at all to indicate any errors. The hot water water demand light comes on and the pump runs but the fan does not kick in. The PCB has been changed already I dont think its the PCB. Since heating works ok I'm assuming the APS and fan are OK.

Worth checking that the pump flow switch is making. It make be okay on heating but not moving out enough on hot water? Stretched diaphragm or restricted flow through plate hex maybe? It sounds like the pump isn't being detected?

 

[Nas]

Just to conclude this thread. It indeed was a faulty the DHW temp sensor. The resistance was 25K should have been around 10K.