Motorised Valve Faulty?

[MartyJ76]

Hi all, hoping someone might be able to shed a little light on a 2 port motorised valve that I dont think is operating correctly on the CH side of my system.

The system was installed only 2 years ago. The valve on the DHW side of the system is operating correctly. However, on the CH side, am getting only minimal heat to rads. 

With the valve lever set hard left to Auto, it appears the valve lever seems to revert after a while to a position off left of centre. Is this where it should be? Not hard, full travel left? 

 

If I push the lever to manual, there is resistance to complete hard right. But nothing will make the lever sit in the groove to keep it locked to manual, it reverts to a position just to the left of full right (apologies for this description, dont have the terminology).

 

In the latter scenario therefore, the closing lever plate inside the head unit is pushing the red microswitch, but it moves back and therefore the tiny red switch does not remain pressed?

 

An audible click can be heard in the electrical controller box when the manual lever is fully depressed, and a second click when it moves away from the microswitch. Its turning on, and then off, right?

 

I understand the lever should remain in Auto at all times, whilst when demand is pressed on thermostat the system deliver heat for 5 mins, and thereafter nothing. I should add, and most will have guessed, this is on an Air Source Heat Pump set up. But my query is only upon knowledge of working 2 port motorised valves. Any suggestions as to whether this unit is functioning as it should?

 

Thanks so much, this site is a lifesaver, every time.

[Mattg4321]

Is this a Honeywell valve?

[ProDave]

What make of valve, different makes behave differently?

 

If you remove the actuator head from the actual valve, does the actuator move correctly off the valve?  does the valve spindle rotate freely with the actuator head off?