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Thread: 4 HR92s in same zone not opening equally

  1. #1
    Automated Home Jr Member Freeco's Avatar
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    Default 4 HR92s in same zone not opening equally

    I have my EvoHome system with 8 HR92s for 4 zones since November. My plumber hooked up the wireless receiver to our heater, but all the rest I did myself (as my plumber is old-fashioned an has no experience whatsoever with EvoHome). I'm an IT guy, so what can go wrong
    I had some difficulties at first, but I managed to work most things out.

    The strange thing that's still left is that the 4 HR92s for my living room zone don't turn open the valves equally. They do work in sync, so open/close at the same time, but the percentage they open is not the same. Eg: 2 open 10%, the 3rd opens 20%, while the 4th opens 30%.
    At first the 2 HR92 that always open more than the other 2 where connected to the 2 smallest radiators in the room. I had to switch them around to be able to properly heat the room.

    So now I have the 2 HR92s that open most on our 2 biggest radiators, and the 2 that open least on the smallest radiators.
    Problem solved, but still... I find it odd they're not all on the same %.
    Anyone an explanation? Or can I still reconfig something?

  2. #2
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    Is this zone set to multi-room or single room?

    Did you fully open the valve using the black disc before attaching the head?

    Are they all configured with the same stroke setting?

    Mine don't always open the same amount in the same zone, but they're not usually that far apart.

  3. #3
    Automated Home Jr Member Freeco's Avatar
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    The zone is set to single room. All 4 zones are, for that matter.
    I believe completely open, but I'm not entirely sure. I either had the black rings completely closed, or completely open. That I am sure.
    The stroke is set to 1 on these 4 HR92s. I had to check, cause it's been some time since I last changed things. I believe I tried first with the default 0 (standard stroke, recommended), but changed it to 1 (full stroke) just to see if it would change anything. I actually don't understand what the difference is between standard vs full stroke.

    The difference shows when the room is more or less at the desired temperature, but needs just a little heating. 0,5-1C or so.
    Just as a test to recheck the valve opening again I'm currently asking +2C temp increase and they all opened to 100%. But I expect they'll drift off again as the target comes near.

  4. #4
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    Apropos to this discussion I think... I have two radiators in my living room - one large and one small. I have a spur leading off to a dining room in a recently built extension with a large radiator. The 15mm piping hits the LR large radiator first, then the LR small radiator and spurs off to the large radiator in the dining room. The consequence of this is that LR small radiator is always cooller that either of the large radiators in the LR and DR. Of course, I guess I could easly correct this by reducing the flow through the dining room radiator but I have never bothered. Ten years ago I spent much time in so-called radiator balancing activities but eventually gave it up as a waste of time. Once the dining room is up to temperature flow reduces through the DR radiator anyway. I use a separate DTS92 in the LR BTW.

  5. #5
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    Quote Originally Posted by Freeco View Post
    The strange thing that's still left is that the 4 HR92s for my living room zone don't turn open the valves equally. They do work in sync, so open/close at the same time, but the percentage they open is not the same. Eg: 2 open 10%, the 3rd opens 20%, while the 4th opens 30%.
    At first the 2 HR92 that always open more than the other 2 where connected to the 2 smallest radiators in the room. I had to switch them around to be able to properly heat the room.

    So now I have the 2 HR92s that open most on our 2 biggest radiators, and the 2 that open least on the smallest radiators.
    Problem solved, but still... I find it odd they're not all on the same %.
    Anyone an explanation? Or can I still reconfig something?
    I'm not sure why you're expecting them all to be identical when the radiators are different ?

    Valve position (option 10 in the HR92 menu) is an indication of the pin travel of the valve, but every valve body is going to be slightly different despite the calibration process that the HR92 performs when you fit it with the black wheel unwound, and the point at which the valve starts flowing will differ.

    If they just blindly moved the pin to the exact same position for all three valves and it turned out that the valve bodies were significantly different (different brands for example) then you could easily end up in a situation where one radiator gets hot and gets the room up to temperature but an identical pin movement on the other radiator doesn't let the radiator get hot at all. That's obviously undesirable as you'd want a balanced total heat output from the various radiators.

    You say the two smaller radiators were being opened more - but to me that makes sense that they would need to be opened more in relation to the larger radiator if you want balanced heating around the room.

    If you have swapped the HR92's around then they will be unaware that they are now on different radiators, but will gradually adapt to their new circumstances. I'll bet that if you check again in 2 weeks you'll find that the HR92's on the smaller radiators are once again opening more than the one on the large radiator - and if this happens, I'd say it's by design.

    You don't say where the temperature sensor for the zone is ? In a single room zone there is only one sensor, so unless you have a wall mounted sensor one of those 4 HR92's is the sensor for the zone. In that case swapping them around will obviously change things quite a bit as you are now measuring the temperature from a different part of the room beside a different radiator. Something to keep in mind.

    When you say you had to move them around to "properly heat the room", what do you mean ? Do you mean it wasn't getting up to the indicated temperature ? Because if the room is consistently under temperature they will keep gradually opening the valves until it can reach the set temperature - even if they need to open the valves 100% to attain the set temperature.

    So there shouldn't be any reason why the room couldn't reach its temperature before swapping them around.

  6. #6
    Automated Home Jr Member Freeco's Avatar
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    Quote Originally Posted by DBMandrake View Post
    You say the two smaller radiators were being opened more - but to me that makes sense that they would need to be opened more in relation to the larger radiator if you want balanced heating around the room.

    If you have swapped the HR92's around then they will be unaware that they are now on different radiators, but will gradually adapt to their new circumstances. I'll bet that if you check again in 2 weeks you'll find that the HR92's on the smaller radiators are once again opening more than the one on the large radiator - and if this happens, I'd say it's by design.

    You don't say where the temperature sensor for the zone is ? In a single room zone there is only one sensor, so unless you have a wall mounted sensor one of those 4 HR92's is the sensor for the zone. In that case swapping them around will obviously change things quite a bit as you are now measuring the temperature from a different part of the room beside a different radiator. Something to keep in mind.

    When you say you had to move them around to "properly heat the room", what do you mean ? Do you mean it wasn't getting up to the indicated temperature ? Because if the room is consistently under temperature they will keep gradually opening the valves until it can reach the set temperature - even if they need to open the valves 100% to attain the set temperature.

    So there shouldn't be any reason why the room couldn't reach its temperature before swapping them around.
    The radiators are all same model/brand, btw. They just differ in dimensions. They also have their own tubes to supply them with heated water.
    I've swapped the HR92s around back in late November. They should have adapted by now ;-) And I did a full reset of the whole EvoHome system (both controller and all HR92s) in December as well.
    I use the HR92s as sensor. The controller is in the same room, but somewhere in a corner on a cupboard. I choose not to use it as the main controlling sensor for the zone because I don't have better spot to put it (with my wife's approval ). Someone told me the first HR92 added to a zone is used as the sensor for the zone. I've used one of the HR92 that opens most as the first in the zone and connected it to radiator quite central in the room.
    The first situation was simply annoying at the point where the target temp was almost reached and the valves started to close down. Radiators make a hissing sound when water runs through them (evohome or not). It drove my wife nuts, as it took very long to reach the actual target with hardly any heat coming from the 2 biggest radiators. Swapping them around improved that a lot.

    if it's normal behavior, I can live with that you know. The current situation is OK. I only find it odd they're that different individually, and that difference stays when moving them around (even after a reset).

  7. #7
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    Interesting. I just checked the valve positions of our 5 radiator zone and they are all absolutely identical at 37 and all are mid-warm. One of those radiators is larger than the other 4. However Im using a room sensor rather than one of the HR92s as sensor. The other thing I would say is that the black wheel was wound out before mounting and clipping in place the HR92s and they are all fitted on new Valencia valve bodies.
    Last edited by rvb99; 9th March 2018 at 12:35 PM.

  8. #8
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    Same for me. I have two rooms set up as single-room zones using wall mounted sensors, one with two rads and one with three, all with HR92s. The valves within each zone always report the same valve position as each other.

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