Very interesting but a bit too technical for me!
I do not have much electrical knowledge and failed to understand the checking procedures from this article.
Sorry about that, let's try another way.
1. Turn the power off to the system (
Setting CH and HW to OFF at the programmer is NOT sufficient).
2. This resets the motorized valve; manual lever should be at left end of slot.
3. Remove the actuator. (Don't disconnect the wiring)
4. Move the lever to the right end of the slot and push the lever in.
5. Replace actuator and pull the lever out.
6.
Check that the lever returns to the left end of the slot and there is resistance when you move it to the right end.
7. Turn CH and HW stats to minimum.
8. Turn power ON.
9. Turn HW ON at the programmer and Turn HW stat to Max.
10.
Boiler should light and only the pipe from valve to cylinder get hot.
11. Turn CH ON at programmer and CH stat to Max
12.
Boiler should run and valve move to mid-position (the lever will be loose in its slot); both pipes from valve should get hot.
13. Turn HW OFF at programmer (do not touch HW stat)
14.
Boiler should run and pipe from valve to CH should stay hot; pipe to cylinder should cool down.
15. Turn HW ON and Turn HW stat to Min
16.
Boiler should run and pipe from valve to CH should stay hot; pipe to cylinder should cool down.
Let us know what you find.