Balancing EvoHome zone with multiple HR92s

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  • emmeesse68
    Automated Home Guru
    • Dec 2014
    • 103

    Balancing EvoHome zone with multiple HR92s

    Hi all,

    I recently added a few HR92s to my heating system and I came across a behaviour I can't explain.

    There are two radiators in my bedroom: one (medium/large) under the window, valve being just under the windowsill, partly covered by curtains. Surely not a great spot for a temperature sensor. The other is a smaller one, "ladder" shape, valve very close to the floor, the opposite side of the window. It's not covered, but the floor is rather cold (downstairs there's an unheated cellar), so the measured temperature isn't the best either. Waiting for a wireless thermostat that I ordered to arrive, I configured the small radiator as the zone "master" (temperature sensing).

    Now I can actually heat the room to a decent level, but after reaching the programmed setpoint the "master" radiator stays warm, while the other closes and cools down. That doesn't feel very comfortable, since one side of the room stays warm while the opposite side is cooling down (I sleep on the cold side... ).

    Can anyone explain why this happens? Any suggestion how to fix it?

    Thanks!
  • erik
    Automated Home Guru
    • Feb 2015
    • 244

    #2
    Do you have the multi room parameter for the zone set to multiple rooms? Or to single room?

    Comment

    • G4RHL
      Automated Home Legend
      • Jan 2015
      • 1580

      #3
      Does sound like it has not been set to one single zone but if the ladder radiator is in an enclosed area such as an open plan en suite then that area could heat up leading the system to think all his good. Just a thought.

      Comment

      • emmeesse68
        Automated Home Guru
        • Dec 2014
        • 103

        #4
        Originally posted by erik View Post
        Do you have the multi room parameter for the zone set to multiple rooms? Or to single room?
        Good question... I had to double check but I was pretty sure it was single zone configuration, as I actually confirm.

        In a single zone/single room config there's one sensor and many actuators. In such a case, do config parameter such as temp offset or stroke or open windows sensitivity matter on slave valves (those that are not acting as a sensor)?

        Actually, at first my big radiator was master, then I couldn't achieve correct temp reading because it is recessed under the windows ledge and behind curtains, so I re-binded the zone with the ladder radiator as sensor.

        When my bedroom is heating up, both radiators work well. The unwanted behaviour I described happens after setpoint has been reached, it seems that the ladder radiator (it's not in an enclosed area actually) could heat up its own sensor enough even when the other one shuts off - chilling out half of my bedroom...

        Valves seem to behave independently, they don't always adjust at the same time (except when setpoint is changing).

        Is there a way to balance valves, or to know how they balance? Or might I delete and rebind the zone, to reset signature, and let EvoHome learn it again?

        In the future I plan to fit HR92s to other rooms in my house. Most of those rooms have two radiators. Dunno if separate wireless thermostats could fix that behaviour, but it feels a bit overkill to fit additional thermostats to every room with more than one radiator, when there's at least one that can be used as a sensor... Is there anyone that could share experience about multiple actuators in single rooms/single zones?

        Comment

        • erik
          Automated Home Guru
          • Feb 2015
          • 244

          #5
          If it's set as single zone, it should behave like you want it to. Both actuators should basically do the same thing. You can check by checking (I think) parameter 10 to see how much % the actuator valve is open. It should be about the same percentage on both. Although the actuators don't act exactly at the same time, so there might be a 2-3% percent difference.

          It could be that 1 radiator valve is different than the other. This could mean it's closing at a certain valve percentage, while the other is still open at that same percentage. I don't think there's a way to 'calibrate' them to be balanced. You could try setting parameter 6 to 1 on the big radiator one. See if that causes it to stay open longer. Or you can re-calibrate them by taking the hr92 off, turning the black wheel all the way counter-clockwise. Then put it back on and wait for CYCLE to complete.
          Last edited by erik; 27 February 2015, 10:18 PM.

          Comment

          • top brake
            Automated Home Legend
            • Feb 2015
            • 837

            #6
            Originally posted by erik View Post
            If it's set as single zone, it should behave like you want it to. Both actuators should basically do the same thing. You can check by checking (I think) parameter 10 to see how much % the actuator valve is open. It should be about the same percentage on both. Although the actuators don't act exactly at the same time, so there might be a 2-3% percent difference.

            It could be that 1 radiator valve is different than the other. This could mean it's closing at a certain valve percentage, while the other is still open at that same percentage. I don't think there's a way to 'calibrate' them to be balanced. You could try setting parameter 6 to 1 on the big radiator one. See if that causes it to stay open longer. Or you can re-calibrate them by taking the hr92 off, turning the black wheel all the way counter-clockwise. Then put it back on and wait for CYCLE to complete.
            The heat output of the radiators needs to be balanced

            To ensure an even distribution of the hot water to the radiators in a system you’ll need to do what’s known as balancing the system. Because the water is pumped via a pipe, and branches to feed each radiator, the ones at the beginning of the ‘run’ tend to get more than their fair share. […]


            Evohome will then be able to control the room temperature in a balanced way

            The manual doesn't cover this as it assumes that the installer already did this, it is mentioned in youlearn chapter 6

            Excerpt:

            It is important to balance the heating system so that hot water is distributed evenly to all the radiators. This will ensure that the heating system operates efficiently and effectively.

            With an unbalanced system, customers may complain of cold radiators or radiators not heating up quickly enough. This is because the hot water is finding its easiest circulation path, which will normally be through those radiators closest to the boiler.
            Last edited by top brake; 27 February 2015, 10:28 PM.
            I work for Resideo, posts are personal and my own views.

            Comment

            • erik
              Automated Home Guru
              • Feb 2015
              • 244

              #7
              Balancing the heat output of your radiators isn't going to help AT ALL if the HR92 closes the valve on 1 radiator and not on the other. You can balance the radiators all you want, but a closed radiator valve will make it output 0 heat, no matter what.

              Comment

              • top brake
                Automated Home Legend
                • Feb 2015
                • 837

                #8
                Originally posted by erik View Post
                Balancing the heat output of your radiators isn't going to help AT ALL if the HR92 closes the valve on 1 radiator and not on the other. You can balance the radiators all you want, but a closed radiator valve will make it output 0 heat, no matter what.
                Agreed but it does need to be balanced nonetheless

                When they are balanced (and that eliminated) if still issue I would delete the zone and bind again with a wireless thermostat on the wall as the sensor
                Last edited by top brake; 27 February 2015, 11:05 PM.
                I work for Resideo, posts are personal and my own views.

                Comment

                • erik
                  Automated Home Guru
                  • Feb 2015
                  • 244

                  #9
                  Yes, and he needs to brush his teeth, too. But it has nothing to do with the subject.

                  Comment

                  • top brake
                    Automated Home Legend
                    • Feb 2015
                    • 837

                    #10
                    Originally posted by erik View Post
                    Yes, and he needs to brush his teeth, too. But it has nothing to do with the subject.
                    Very helpful
                    I work for Resideo, posts are personal and my own views.

                    Comment

                    • erik
                      Automated Home Guru
                      • Feb 2015
                      • 244

                      #11
                      Originally posted by top brake View Post
                      Very helpful
                      Just as helpful as your post. At least I was helpful in the post before it...

                      Changing temperature sensor is questionable advise as well. The issue is not with the temperature sensing, the issue is one radiator valve closing while the other isn't closing. Another temperature sensor isn't going to change that.
                      Last edited by erik; 27 February 2015, 11:23 PM.

                      Comment

                      • emmeesse68
                        Automated Home Guru
                        • Dec 2014
                        • 103

                        #12
                        Just to summarize... I had to balance my heating system myself (before I installed any EvoHome component), since I realized a few months ago that my former installer didn't bother and left all lockshield fully open (I think he didn't brush his teeth as well ).

                        My bedroom HR92s are not configured the same way, because the one driving the ladder radiator (the one that stays warm, and acts as as a sensor) is configured for full stroke sincee at first it didn't open enough and the radiator didn't heat up. The other valve is set for normal stroke because it doesn't need full stroke to open/close my bigger radiator properly.

                        Offset also is differently set, because I configured the big radiator to -2 degrees when, in the beginning, I tried to use it as a sensor. I left it as it was when I switched to the other one, that's set to an offset of -1. But if this counts, in my opinion it would have made valves behave the opposite way than they are doing now.

                        Anyway, the two valves don't show the same opening %. When the unbalanced behaviour happens, the ladder radiator valve is usually 60 - 70% open, while the big (and cold) radiator would be only 10 - 15% open - that doesn't look too close to the other.

                        The difference isn't constant, either. Now the big radiator is 39% while the ladder one is 59% (different enough but the big one is not closed, at least). Earlier this evening they were both working close to 100%.

                        The unbalancing appears when the room setpoint gets reduced (e.g. wnen my schedule sys I want to switch from 21 degrees to 20), but not every time - or, at least, it's not always that evident.

                        And I was planning to addd an additional wireless thermostat anyway, because neither valve is in a decent position to act as a sensor. Thermostats order is takng a bit longer than expected, so I have to wait ...and I'd really like to understand how multiple valves in a single zone act together, since I'm planning to install hr92s all around my house... most rooms I'm going to fit with have two radiators, I'm afraidthat if I'll have to fit wireless thermostats everywhere I'll be spending on batteries what I'm saving on heating

                        Comment

                        • erik
                          Automated Home Guru
                          • Feb 2015
                          • 244

                          #13
                          I would try to reset the HR92's and remove the zone and redo it. Seems like something is wrong (the very different valve positions).

                          I had 2 running in my living room and they were always almost the same.

                          Comment

                          • G4RHL
                            Automated Home Legend
                            • Jan 2015
                            • 1580

                            #14
                            My two in my living room always read the same and one has a settee in front of it and is in a draught free corner.

                            Comment

                            • JohnnyP
                              Automated Home Jr Member
                              • Nov 2008
                              • 38

                              #15
                              This may not help... because I've a Hometronic setup, but the HR92s are the same, so... If I had your situation with two quite different radiator locations in the same zone, I would not explicitly assign one of the HR92s to be the temperature sensor, simply bind them both to the same zone and let them get on with it. This has the positive effect that both HR92s act independently in maintaining the same setpoint locally, but in Hometronic has the negative effect of not being able to display the achieved zone temperature at the controller. Alternatively, I would buy one of the wall-mounted temperature sensors and explicitly assign that as the sensor, which would enable achieved zone temperature reporting at the controller.

                              Comment

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