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Thread: Springing HR92s

  1. #1
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    Default Springing HR92s

    I have two radiators where I had to use the plastic adaptor that screws on for the HR92 to fit as the valve is a Danfoss one. I installed all in December 2014 and twice in that time on one of the radiators the HR92 has sprung off. The adaptor screws on tightly and it is not unscrewing so I am assuming the pressure to operate the valve pin is forcing off the HR92. Anybody experiencing this?

    I assume it may be the valve is sticking (20 years old)and too much effort is needed to operate it causing the HR92 to come off but the present pin seems to push in and out without any problem, it may be stiff but does not seem unduly so. The ultimate cure will be to replace the valve I suppose. I have replacements for all my valves but can't be chewed and I have been waiting until a good time occurs - when the old boiler fails!

    By the way, springing off on to the floor did not trigger a fault report in the Control Panel.
    Last edited by G4RHL; 26th February 2017 at 12:50 PM. Reason: Additon

  2. #2
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    You won't get an entry in the fault log book. Even if the latch on an HR92 is open (and is therefore non-functional, since it won't turn the motor) no fault will be logged...

  3. #3
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    I seem to recall that DanD discovered that an HR92 whose latch is unlocked sends a unique heat demand figure that is outside of the normal 0-200 range, and can thus be recognised as a fault. It's a pity the controller doesn't act on this to report that an actuator is not functional and may not be latched properly. (Could be included in a software update...)

    However if yours sprung off the radiator with the latch still in the closed position I don't think even the HR92 itself would be aware there was an issue, as it would think it was still on the radiator, with the only clue being that the pin was "too easy" for it to depress.

  4. #4
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    I have the plastic adapters on all my valves and I have only had one case where the HR92 has failed to operate properly. Ironically, this was when the HR92s were first fitted. I found one of my HR92s sitting on top of the adapter with the latch locked (an before you ask, I didn't install them). I am not sure how this happened. I re-sat the HR92 properly on its adapter and it has been fine ever since.

    With the adapters, I do find that I can get the occasional case of pin 'stiction': this usually results in a slight clunk when the valve first opens. I exercise the pins on my TRVs a couple of times during the summer months. I have yet to hear Evohome do a fortnightly cycle.

  5. #5
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    Yes my HR92 sprung off with the latch closed to lock it so logically, yes, the Panel would not know. It has happened 3 times over about 27 months on the same radiator. Could be the threads on the adaptor are not too good but it feels solid and tight when on. Having said that there must be some weakness and I lean toward it being the pin is stiffening up to make it harder work to drive it.

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