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Thread: Issue with HR91 / radiator valve

  1. #1
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    Default Issue with HR91 / radiator valve

    I finally got around to installing a HR91 onto the radiator in my dressing room, the only one that didn't have an evohome valve on it.

    When I installed the system a couple of years back, I changed all the radiator valve bodies in the house to brand new Honeywell Valencia ones. This dressing room radiator still has the old valve body, as I didn't change it at the time, but it is also a Honeywell Valencia, albeit an older one.

    When using the manual TRV and when installing the HR91 (when I turn the black knob fully anticlockwise), the radiator gets scalding hot, so the valve body itself functions properly.

    However, with the HR91 installed, it seems as if it closes the valve properly but does not open it enough to let the radiator get hot.

    I can set the temp to 30 degrees and the radiator still stays cold, even though the evohome controller thinks the valve is 100% open. I've reset and rebound a few times and still the behaviour is the same.

    I'm beginning to fear I may need to spend more money and buy a substitute HR92 where I can change the stroke mode, unless I'm missing something obvious here that I should be doing?

    Anyone have any suggestions, or does this look like a stroke mode issue that can only be solved with a HR92?

  2. #2
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    Quote Originally Posted by rs1987 View Post

    Anyone have any suggestions, or does this look like a stroke mode issue that can only be solved with a HR92?
    I bought an HR92. Stroke 1 mode fixes the problem and the valve opens.

  3. #3
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    Quote Originally Posted by rs1987 View Post
    I bought an HR92. Stroke 1 mode fixes the problem and the valve opens.
    I tested an HR91 sample when they first launched but one of the reasons I returned it was this issue - the stroke is insufficient for some valve bodies and there is no Stroke 1 equivalent setting like the HR92. (or indeed any settings at all)

    While I'm sure the HR91 works fine for some people I can't recommend them. You lose a lot of functionality and compatibility for a relatively modest decrease in price.

    In 6 years I've only had one HR92 fail - and that was physically destroyed by a toddler. (Screen ripped off - repaired, then ripped off again!) While they have issues with the battery contacts needing re-tensioning from time to time (I do it when I change the batteries) other than that I've found them pretty reliable.

  4. #4
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    Quote Originally Posted by DBMandrake View Post
    I tested an HR91 sample when they first launched but one of the reasons I returned it was this issue - the stroke is insufficient for some valve bodies and there is no Stroke 1 equivalent setting like the HR92. (or indeed any settings at all)

    While I'm sure the HR91 works fine for some people I can't recommend them. You lose a lot of functionality and compatibility for a relatively modest decrease in price.
    When I originally bought them the price differential was more substantial than today. I can get HR92s today for literally half the price they were when I first installed my Evohome. The other factor that leaned me towards the HR91 at the time was the relative quietness of the motor compared to the HR92.

    Today, I would definitely buy all HR92s for this very reason of compatibility / great control via the settings. I think I probably got lucky as I replaced all my TRVs with brand new Honeywell Valencia's when I first installed the system and didn't run into this problem until now when I tried to install a valve on an older TRV body.

  5. #5
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    Not quite the same situation, but I have some TRV bodies that do not open 100% when the HR92 adapter is screwed on and the black wheel fully unscrewed, as the pin in the TRV is slightly too long - you can hear a slight restriction in the flow when fully open.

    I solved it by removing the steel pin from the adapter (it just pulls out) and used my bench grinder to take about 1mm or maybe a bit less off, then put the pin back.
    You could perhaps use the same technique to 'shift' the range of the pin travel. Although if it doesn't work you might find it difficult to add that extra 1mm back on again!

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