Programmer or valve not working?

[BlackRod]

I fitted a new programmer (Honeywell 9400C) to my heating system last September. I thought everything was OK but now I find that the water won't heat up without the heating being on. Not a problem in the winter but will be now. So, what I have is:

CH on and HW on - OK
CH on and HW off - OK
CH off and HW on - Both are off

With the CH set to off, when I switch the HW on the light on the programmer comes on but nothing happens (the boiler doesn't fire up). When I switch the HW off the light goes off and there is a noise that sounds like a valve closing (if I move it the lever will return to its original position). There is a second valve (looks like a three way). I can move the lever freely but it doesn't appear to do anything in response to the CH/HW being turned on/off.

My question is: From what I have described is this likely to be a wiring fault at the programmer or a fault with the valve? I don't want to check/rewire the programmer if what I have described above means that the problem must be with the valve.

If it's relevant the CH controls are quite old. There is a frost thermostat, but no room thermostat. All the radiators are fitted with TRVs. There is an electric immersion heater in the hot water tank but I can't see a thermostat. Boiler is a BAXI Combination about ten years old.

Thank you for reading this, I hope it makes sense.

 

[petertheplumber12]

You do not have a baxi combi it is something else, I think you have a fault with your motorised valve wiring, since by default the at rest position with the motor is hot water. This means including programmer wiring problem.