Intermittent problem with motorised valve

[flutterbye]

I replaced the actuator to a BG branded MV a couple of weeks back since it was stuck open and I thought that had solved the problem. Its a on/off vale controlling HW only.

Most of the time, it works as expected, opening/closing the valve and switching on the pump etc dictated by the HW stat and controller.

However, around once per week, I've noticed it too stays stuck open with pump on.

MY theory is (and this is what I'd like to check with others) is that maybe the valve itself which I didn't change yet, gets stuck a little so the spring in the actuator doesn't have the force to close it? Is that plausible or is it most likely to be something else?

When the actuator is off and I can see the spindle I can always turn it by hand which is what makes me doubt my theory...

Any insight gratefully received !

 

[Dickie1]

Replace with a complete new 2 port valve mate, it does sound like it is jamming.

When you have the system drained down to do this; Fit two valves on the outlet side on both 2 port valves, this will enable you to replace faulty 2 port valves in the future.

You would isolate the a pump gate valve & the two valve you've fitted, this then lets you work on the circulation pump & both 2 port valves - without the need to drain the system..............We pros have been doing this for yonks!!!