Nest 3G wiring help

[Dave OCD]

When the stat is satisfied the valve actually closes on a spring return as power is removed from the motor - unless it's a 3 port valve which is slightly different.

 

[Arb]

When the stat is satisfied the valve actually closes on a spring return as power is removed from the motor - unless it's a 3 port valve which is slightly different.

Yes which appears to be happening yet hot water still gets through. I have an older Honeywell valve and can only take it apart so far before bad things happen, I can remove the synchronous motor and that's about it.
I will buy a complete unit to fit in the new year as I am satisfied that I have exhausted all avenues and have a pretty firm diagnosis that the valve is not seating for one reason or another.

Thank you all for your professional help and not being to brutal about my amateur efforts and non compliance.

 

[diditrain]

When you are calling for heat only, have you checked for voltage on the brown conductor of the valve?

 

[Arb]

When you are calling for heat only, have you checked for voltage on the brown conductor of the valve?

No I didn't, although I did disconnect the stat to the valve for 24hours so 0 Volt to the motor and hot water was still getting past, the case states the valve is normally closed so I assume it's not seating correctly. Once the stat once connected it functioned as it should along with the motor operating and boiler firing.

But I will double check over the weekend just to be sure.

 

[freddo]

When the wires to the nest receiver come from behind, use the rear knockout holes, that's what they are bloody there for!!!!!!!!!!!

Whoops, missed the date!