Mid position valve problem

[shaggie16]

Hi, can anyone help?
I hve recently had to drain the system completely, twice, to have a radiator replaced, but I'm hoping this is incidental to the problem.

Gledhill thermal store - but that's irrelevant really. Hot water is fine (valve in the non-actuated position.) Central heating only gives a tiny amount of warmth on the rads (not hot at all) even though the store is well up to temp.

If I put light pressure on the lever on the valve acuator, even when the heating is called, it has not moved very much at all. If I manually push the lever to the central position, the rads get piping hot. The room stat is satisfied, the valve actuator returns under spring pressure, but when the room stat calls again, the same problem occurs.

The valve body (not the actuator) was changed earlier this year. I have taken the actuator off, and the valve spindle is easily and smoothly rotated with finger, so I assumed the actuator was duff. However, with the actuator NOT on the valve body, the actuator operates exactly as it should! This confuses me, as I say, the valve spindle itself on the body of the valve can be rotated with light finger pressure....

Is it possible for an actuator to become weak or am I barking up the wrong tree?

Thanks in advance,

-m.

 

[Agile]

It would be better if you told us which tree you are barking up!

What make of motor valve???

 

[TCCHeating]

Yes. Sounds like weak syncron motor. First thing to do is check that it is receiving the full 230v. If it is then change it

 

[shaggie16]

Sorry - it's a Danfoss valve with an HSA3 actuator. The tree I'm barking up is thinking that it's the actuator, it's just I thought I would check first as the valve is so easy to turn by hand that it seems strange the actuator is not strong enough to do that. But I guess it can't be a lot else.

 

[shaggie16]

Yes. Sounds like weak syncron motor. First thing to do is check that it is receiving the full 230v. If it is then change it

Thanks for that - hadn't thought to check the voltage - doh! Will do so and act accordingly. If it isn't receiving the 240V then I assume that's down to the control board on the dreaded Boilermate...

 

[Agile]

Also check that when assembled the driving spline and the valve shaft are free to turn and not binding.

Tony

 

[shaggie16]

Also check that when assembled the driving spline and the valve shaft are free to turn and not binding.

Tony

Thanks - that's the source of my confusion - valve shaft turns properly with very little finger pressure- hence why I don't see the actuator having a problem turning it (especially as the actuator turns properly when removed from the valve.) But I just wanted to sanity check my theory of it being the actuator before I picked one up.