I've replaced a new Drayton trv 4 myself on the first week of November with the same issue. Now it's broken AGAIN! I've attached the image here of the broken valve. Can anyone determine what's the cause of this broken valve? Is it the quality or what are the causes??
I found eQ-3 electronic at £15 each in 2019 may be more expensive now, these exercise the valve mid day every Saturday to stop them sticking, and come up with a fault report if over or under travel, so you know if pin has stuck. And of course programmable and actually work in degrees C no silly *123456 so would not fit mechanical heads any more.
You can try freeing the pin off- have a search in this forum, it's not a rare problem. WD40 and a spoon are popular. And yes that'll be why your new head has failed.
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