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Thread: TRV not opening fully

  1. #1
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    Default Evohome: TRV not opening fully

    I have a problem with at least one HR92 actuator. With the actuator fully open, the rad valve is not fully open. It's open most of the way but it still restricts flow slightly and this impacts the amount of heat the rad can put out.
    I use Honeywell Valencia TRVs. Should I assume that, when the HR92 actuator is fully open, it shouldn't be applying any pressure to the TRV pin?
    Last edited by skwerl; 29th November 2021 at 05:06 PM.

  2. #2
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    The HR92 has a variable stroke setting to deal with situations like this. try that first.

  3. #3
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    This is with the HR92 head removed and only the actuator body left in place. Ie the black wheel that drives the pin. In fully open position it is pressing on the TRV pin slightly

  4. #4
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    Ah, yes I have heard of people report this issue. Besides the obvious fixes, I thought I heard of a collar that might be available to increase the distance between the TRV pin and the HR92 pin.
    One more reason why I recently stuck with the Pegler valves. They have just worked flawlessly for me.

  5. #5
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    Yeah. They come with various collars but being Honeywell Valves youíre supposed to just fit the actuator directly. Iím going to email Honeywell and ask for their input. Itís only a minor problem on rads that are towards the end of the circuits.

  6. #6
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    I had the same problem with some 'decorative' type TRV bodies, you could hear a little bit of restriction when the HR92 was fully open.
    The easiest solution I decided was to simply remove the steel pin from the toothed black wheel on the valve adapter (it pulls straight out by hand) and grind about 0.5 to 1mm off the end using my bench grinder. Job done.

  7. #7
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    Yeah. I thought of that as a last option. Itís more a point of principle that HW valves donít seem to work as well as they should with their own actuators. And I canít be arsed! I mailed HW support to hear what they have to say

  8. #8
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    Yes it does seem a bit odd that you are getting the issue with Valencias. In our last place when I first installed an Evohome system I installed Valencia bodies and they worked perfectly, so I wonder if maybe you have a dodgy batch.

  9. #9
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    Quote Originally Posted by skwerl View Post
    Yeah. I thought of that as a last option. It’s more a point of principle that HW valves don’t seem to work as well as they should with their own actuators. And I can’t be arsed! I mailed HW support to hear what they have to say
    I assume you haven't read my thread on this issue:

    https://www.automatedhome.co.uk/vbul...encia-problems

    I installed Valencia's and same as you found they don't work properly with the HR92 by default!

    In the end I used Stroke 1 mode on all my HR92's and they work fine now. Regarding the pin travel, they have a lot more pin travel than other brand valves however this is due to the threaded insert which allows balancing to be performed on the same valve as the TRV instead of at the lockshield valve as is traditionally the case.

    I don't recommend balancing the radiator using the balancing insert when using an HR92 - just unscrew the insert until it comes lose then turn it back in slightly. This will give the appearance that the HR92 adaptor is pressing the pin down slightly even when fully extended but this is only travel that would have been removed by adjusting the balancing insert anyway.

    Check out the photos a few posts down in that thread.

  10. #10
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    Yeah. I realised early on that the balancing ďscrewĒ seems like a nice idea but doesnít work as well as a lockshield, so I leave them fully backed out. Iíd refer to that as fully open and so the HR92 shouldnít add any restriction at all. The difference is about 5 degrees C when the HR92 actuator wheel is fitted vs the Valencia in its bare form. Maybe on the Valencia, position 0 is supposed to be applying some pressure on the pin. But there are no instructions as to how to set the Valencia to 0 - my assumption was that 0 was when no pressure is felt and the valve is truly fully open

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