Evohome - poor temperature regulation

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  • erik
    Automated Home Guru
    • Feb 2015
    • 244

    #46
    you're asking for 20. It's delivering 22. It didn't say that on my tin.

    Also, if you will keep the same setpoint in a zone for a day (and close all other zones to prevent them from influencing the result), you will probably see it going from setpoint to setpoint + 1 and back to setpoint and back to setpoint + 1 etc. all day.

    If you do the same experiment with a old Honeywell Round thermostat, it will probably do a much better job in keeping temperature constant.

    Your heating is very very quick by the way. It doesn't slowly build up a huge overshoot like it does for me. It very quickly builds up a overshoot, more like a true accidental overshoot. Less orchestrated than in my case. The circumstances are very different and therefor hard to compare.

    Comment

    • G4RHL
      Automated Home Legend
      • Jan 2015
      • 1580

      #47
      Originally posted by erik View Post

      Your heating is very very quick by the way. It doesn't slowly build up a huge overshoot like it does for me. It very quickly builds up a overshoot, more like a true accidental overshoot. Less orchestrated than in my case. The circumstances are very different and therefor hard to compare.
      "And there is the rub" bit of Shakespeare! Different set ups, different properties, different construction. My house has always heated up quickly - even long before Evohome. It was good from day one for that and got better when we replaced the double glazing and installed cavity insulation.

      Comment

      • G4RHL
        Automated Home Legend
        • Jan 2015
        • 1580

        #48
        Additional note -optimisation.

        This morning I noticed that of three zones all at the same temperature, optimisation came on for two of them an hour before the set point (07:30) - in each case to get them up from a starting temperature of 15 to 18. Puzzled as to why not the third zone as this is the hall and it takes longer to warm up than other zones. Yesterday morning optimisation started heating that zone 20 minutes before the set time. This is the reverse of what I would expect - surely those that take longer to heat up come on sooner with optimisation? No doubt the remaining zone will start to come on at 07:10.

        Addendum 07:07 - it came on 25 minutes before at 07:05.
        Last edited by G4RHL; 15 March 2015, 08:07 AM.

        Comment

        • greyhound1234
          Automated Home Jr Member
          • Mar 2015
          • 33

          #49
          Originally posted by Rameses View Post
          @ All

          I will try to explain.

          At 17 degrees there will still be demand - albeit low. (unless its 17 degrees outside) - so this means that whilst the system has achieved 17 degrees, this does not mean it’s off, for instance the boiler will be operating a water temp of 30 and the Hr92 valves will be open 20 % for example - this keeps the room at your set point - whilst keeping boiler burn to a minimum and energy into the system.

          < at this time the important thing here is Hr92's are open taking the throttled heat>

          If you increase Zone A to 20 degrees you are then making a 100% heat call - which will make the boiler turn up to 70 degrees (dependent on boiler and demand for heat from the rest of the house)- which will go around the 'circuit' - at this point your Zone A valve will more than likely be fully open - but your Zone B valve will still be opened slightly from the previous (and current) operation of trying to keep 17 degrees.

          Zone B will get some heat temporally - and the valve WILL close once it sees that the temp is rising in a way that will jeopardise the 17 degree set point. An amount of heat delivered to the radiator before the valve closes is causing the short temporary overshoot. This is typical and consistent to what you are experiencing with the 1.5 degree ‘overshoot’ but this is both short term and not requiring any more energy that has already been created into the support Zone A. Left alone the zone will go back to 17 degrees. NB: Some customers have incorrectly sized radiators for the room, ie too big or designed, and this can amplify this problem, with a larger mass to cool.

          Please note that if your 17 degree Zone B was set to 10 degrees (ie not calling for heat) – this would not occur as the valve would be fully closed when the heat is injected into the system.

          The Hr92 is designed to operate within its own surroundings it will always find the balance to provide set temperature in the room independently from call for heat from other zone. But the process of finding this balance takes time and it has no awareness of what the other zones are asking for, choosing to operate on what it can experience within the room.

          The zoning system behaviour described above is in contrast to traditional systems where the whole house would rise in setpoint and radiator valves were static and not dynamic in their operation.

          We are sure of the capability of the Hr92 as recently we received EUBAC certification (independent third party testing) endorsing its capability to exercise control, and is best in class with a AA rating.
          [ATTACH=CONFIG]506[/ATTACH]

          I hope this goes a little to explain the behaviour you are observing. Yes there are possible areas for improvement getting even tighter control, but right now these are not possible within this product and as we are demonstrating this is significantly better than previous controls on the market. We are listening – we do read this feedback –and we will aim to improve our products over time.
          Hi Rameses

          Okay I can see that IF the 'zone B' zone valve were operating as you say, then the zone B radiator would be cool, and any transient increase in air temperature would be short lived and not affect the thermal comfort of the room since the radiative temperature of the surroundings would be fairly unchanged and indeed the thermal mass would soak up the tiny bit of extra heat. However, the Zone B radiator was running at full bore, hot, for the hour that Zone A was calling for heat. Until Zone B reached 1.5 degrees over, when it closed.

          Comment

          • greyhound1234
            Automated Home Jr Member
            • Mar 2015
            • 33

            #50
            A picture is worth 1000 words.
            Please see my sketch of how a single zone heating behaviour works.
            Clipboard02.jpg
            This is not from data, but just to illustrate it.

            Comment

            • greyhound1234
              Automated Home Jr Member
              • Mar 2015
              • 33

              #51
              Now, also to point out some interesting observations which may help the bug to be tracked down.

              I have just unbound, reset, and rebound everything.
              Previously, all zones when tested individually used to overshoot like this.
              Now having rebound then, only one is. The first zone.

              I'll say what I did first.
              1. unbind each HR92 at the valve control. (hold binding 15 sec).
              2. Factory reset the controller. Once it says 'I've been reset, green tick', I didn't press the green tick but took the batteries out.
              3. I left it 5 minutes. I put the batteries back in. It says 'you have no zones, choose installer menu or guided config' (I'm paraphrasing here...)
              4. Installer menu. I note that there is a pre-populated zone called living room bound to evohome internal sensor. I tried to edit this zone and bind HR92.
              I noted it does not say 'do you want to add another radiator', unlike adding a new zone.
              5. However, if you do that, it still says unbound when you have finished. And the heat demand comes on permanently. This prepopulated zone is corrupt!!
              6. You can't delete this dodgy zone until you bind another.
              7. I bound the bathroom. (put bathroom HR92 in bind mode, then press 'use evohome internal sensor, no', then press bind. Waited 30 sec on binding received screen before pressing ok (no idea why this is needed).
              8. I deleted the living room. I then bound the other zones and the living room.

              I now notice that the bathroom - zone 1 (which used to be occupied by the corrupt zone) is overshooting, the others are not.

              Comment

              • greyhound1234
                Automated Home Jr Member
                • Mar 2015
                • 33

                #52
                I note impressive control of other zones. The radiators cool down as they pass the set point (typically 30% open as reported by HR92.
                However, zone 1 bathroom overshoot - requested temp 19.0. Actual 19.5 boiling radiator and rising fast, HR92 position 70% open!
                I see a post noting that in guided config, renaming/deleting a zone 'corrupts the database'. Related?

                Things I will now test. Is it zone 1 that is dodgy, or just the bathroom.

                Comment

                • roydonaldson
                  Automated Home Guru
                  • Jan 2013
                  • 205

                  #53
                  Try running the Rf test on every zone. I had a problem where it had the actuator bound fine, but not the sensor.

                  Comment

                  • top brake
                    Automated Home Legend
                    • Feb 2015
                    • 837

                    #54
                    Really pleased you have resolved the issue. This all stems from this 'default zone' assuming that you want to control the Evo as application type 'thermostat' using the Evo internal sensor with Boiler relay. This is how an Evohome base pack is supplied pre-bound. If you factory reset it spoils this. When you go through guided configuration it deletes/overwrites it according to the zone type you select (usually radiators). There is a possibility that if you do a factory reset and then rather than guided config you add zone in installer mode that this 'default zone' can remain. It is not a bug as such but a configuration error.

                    Make sense?
                    I work for Resideo, posts are personal and my own views.

                    Comment

                    • erik
                      Automated Home Guru
                      • Feb 2015
                      • 244

                      #55
                      Originally posted by top brake View Post
                      Really pleased you have resolved the issue.
                      It is not resolved yet as far as I can tell. It improved in the scenario of using multiple zones (hr92's), but not resolved, yet. I will also try resetting and unbinding everything and then reconfigure/rebind everything and make my living room zone 2. And see if it improves. Maybe there's some bug specific to just zone 1?

                      greyhound, what happens if you totally reset/unbind and re-configure/rebind it in single zone (thermostat) modus? Does anything improve at all in that scenario?

                      Originally posted by greyhound1234 View Post
                      A picture is worth 1000 words.
                      Please see my sketch of how a single zone heating behaviour works.
                      [ATTACH=CONFIG]507[/ATTACH]
                      This is not from data, but just to illustrate it.
                      That's exactly what I'm seeing. And after the first 'hump' to 1.5 above setpoint, which you have shown, it will build another hump and another etc. etc. Like shown in this image:
                      evohome-single-zone.jpg
                      Last edited by erik; 15 March 2015, 11:21 AM.

                      Comment

                      • erik
                        Automated Home Guru
                        • Feb 2015
                        • 244

                        #56
                        So I reset and unbinded everything. Then used the guided config. I made my hallway zone 1, Evotouch as sensor, 1xHR92 as actuator. I made the living room zone 2. Round Wireless as sensor, 2xHR92 as actuators. Hallway setpoint is 6, measured temperature is far above, so it doesn't do anything. Livingroom was set to setpoint 17.5 when it measured 16.0

                        Result: Evohome started heating and it measures 18.0 for quiete a while now in the living room and it still keeps asking for heat every 10 minutes. However, the HR92's in the living room are closed. So, the room is too hot and all the extra heat needlessly generated is going through my by-pass, basically being wasted.

                        The HR92's in the living room are set to default stroke. They have been carefully placed on the radiator valves. Black wheel all the way to the left and letting them go through their CYCL. There's a 1 year old Honeywell Radiator Valve (V2000) and a 1 year old Heimeier valve. Both are closed by the HR92. Yet they are still asking for heat from the boiler.

                        Ah, seems the system has finally stopped asking for heat now. It's 18.1 on my own thermometer. Let's see how much it has to cool down and how long it will take before Evohome starts heating again. And let's see to what temperature it will heat once it does...

                        Conclusion so far: no improvement, at all. So... please enlighten me. What did I do wrong? What user mistake did I make?
                        Last edited by erik; 15 March 2015, 05:37 PM.

                        Comment

                        • erik
                          Automated Home Guru
                          • Feb 2015
                          • 244

                          #57
                          It's 1 hour later now. There has been no heat demand for an hour now. Temperature, according to my own thermometer has dropped from 18.1 to 17.4.

                          Just to make things clear, when using an old Honeywell Round as a thermostat, I've never seen my own thermometer going up/down more than 0.3 degrees. So already, Evohome is doing less than half as good as an ancient 'dumb' thermostat.

                          Comment

                          • erik
                            Automated Home Guru
                            • Feb 2015
                            • 244

                            #58
                            and again 40 minutes later my own thermometer shows 17.1 and Evohome has been showing 17.5 for a while now instead of 18. It just started heating again.

                            So in summary: Evohome heats up the room to way above setpoint, keeps asking for more heat even when the valves are closed, then finally stops heating and stays off for 1 hour and 40 minutes and lets temperature drop by a whole degree. Then it starts heating again.

                            For reference: the old Honeywell Round would keep temperature within a 0.3 range. So doing at least 3x better than Evohome.

                            Edit: Oh, and guess what. It started requesting heat again, but the HR92's are still closed (1 was set to 37%, the other to 41%). So no heat going into the radiators. Changed them to full stroke now and let them CYCL again... Let's see if the valve behavior will improve now... Again: these are brand new radiator valves... One of them is from Honeywell. Wtf?
                            Last edited by erik; 15 March 2015, 07:13 PM.

                            Comment

                            • greyhound1234
                              Automated Home Jr Member
                              • Mar 2015
                              • 33

                              #59
                              Originally posted by top brake View Post
                              Really pleased you have resolved the issue. This all stems from this 'default zone' assuming that you want to control the Evo as application type 'thermostat' using the Evo internal sensor with Boiler relay. This is how an Evohome base pack is supplied pre-bound. If you factory reset it spoils this. When you go through guided configuration it deletes/overwrites it according to the zone type you select (usually radiators). There is a possibility that if you do a factory reset and then rather than guided config you add zone in installer mode that this 'default zone' can remain. It is not a bug as such but a configuration error.

                              Make sense?
                              Hi - I need more days to conclude if is has significantly improved, but I got the impression that it was better at least in the zones that are not the bathroom.
                              Though I wouldn't call having one zone that behaves erratically to be 'resolved'.

                              "There is a possibility that if you do a factory reset and then rather than guided config you add zone in installer mode that this 'default zone' can remain. It is not a bug as such but a configuration error. " Indeed, that zone always remains after a factory reset, and if you try to bind this default zone to the HR92s, it all gets very screwy.

                              Do you have any comments on what I read on another post
                              ---------------------------------------------
                              "You should be able to check the firmware version by doing a quick tap on 'settings' on the evohome main screen followed by a long tap (arround 20s) on 'device settings'. The system should then display an info screen with the device id and application software version followed by a date etc."

                              Mine is V25 from 16 janv 2014 and here is a brief description of the bugs I found:
                              - Renaming a zone in the installation menu corrupts the database
                              - Deleting a zone corrupts the database.
                              - Activating the temperature compensations make erroneous readings (HR92 uses their own temp sensor, no more evo's unit even if activated)
                              - Activating optimisation overrides the 2nd time temperature by the first time temp.
                              -----------------------------------------

                              So renaming and deleting zones I was hoping to avoid. Unfortunately, in the guided configuration, if I ask for 4 zones, it pre-populates it with names which I then have to change. What did this person mean by 'corrupts the database'? Would that behaviour lead to temperature overshoot?
                              (I'm thinking, what if I used guided config and ask for 4 zones and leave the names alone?)

                              Comment

                              • erik
                                Automated Home Guru
                                • Feb 2015
                                • 244

                                #60
                                I would just like to say I bought an Evohome Connected (single zone) package and it was pre-configured in the box. So I couldn't have done anything wrong in installation/binding. And even then, it didn't work as advertised (building up 1.5 degree overshoots).

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