Water, but no heating. Possible 3PV?

[Echo the husky]

I was thinking of splitting the unit apart and sticking the unit back in place by the pins so I can get my probe down the back of it while it's still on.

If you are confident doing it like that that's fine, I didn't want to mention doing it that way as it is less safe.

HW only, White=0v, Grey=240v, Orange=0v

This would be correct only if the clyinder had reached temperature or the clyinder stat was turned down. This appears to be the case as the orange has 0V (as is not being back fed via the cylinder stat.)

HW&CH, White=0v, Grey=240v, Orange=0v

Is this correct? Unless you had the room thermostat turned down, the white should have 240V as well. (which would in turn then make the orange 240V) If grey has power the clyinder stat must be turned down, or the clyinder has reached temperature (which as above appears to be the case).

CH only, White=240v, Grey=73v, Orange=42v

That would be expected as you are not getting the HW off signal from the programmer.
If it was working it should be 240V on all of those wires.

Am I right in thinking that the reason there is only 73v on the grey during CH only is due to (apart from terminal 4 on the programmer not outputting the required 240v) the rectifying diode/resistor configuration.

I think you mean terminal 1 of the programmer not putting out the required 240V, and Yes.

 

[SuffolkDave]

Yes, terminal 1 (I was going off terminal 4 of 7). I just wired terminal 1 to terminal 4 and fired it up, boiler kicked in when heating demanded.

The voltages from earlier i tried again with both stats set to max:

HW W=0v, G=0v, O=240v

HW/CH W=240v, G=73v, O=240v

CH W=240v, G=73v, O=42v

If HW is switched on, the valve will not motor when CH is turned on.

So at the minute until I get a new controller, I've opened the valve to manual and set the HW slightly over 50c to take the frost out of the air

 

[Echo the husky]

Yes it is a faulty programmer.

 

[SuffolkDave]

Thank Christ for that. I bet that was like pulling teeth for you eh Freddo?

 

[Echo the husky]

It gives me something to do!