Mains HE24 flame failure on hot water only

[arifhayat]

I have a problem with 24HE flame failure only on hot water, boiler working fine on heating but as soon as hot water micro swich is pressed, it goes on to flame failure. Hot water pin is going in & out fine. No issue of diaphragm. Removed the micro switch off the housing and operate the switch manually, it goes to flame failure. Tried with new micro switch, same result. Can anyone suggest any remedy?
Thanks.

 

[Agile]

Does the boiler fire up for a while before going to flame failure.

If not then it could be an ( unusual ) PCB failure.

Or someone has wrongly connected something.

 

[CBW]

Do you get an error code too?

 

[arifhayat]

The flame failure is instant. There is no codes display on HE24.

 

[arifhayat]

I tried with another PCB, same result. Can it be any sensor?

 

[Agile]

It could be that another fault is detected and just shown as a flame failure.

 

[ianmcd]

when you move to HW and it locks out, is the flame failure light solid or flashing ? if flashing is it twice per second or once every 2 seconds ?