evohome Wi-Fi

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  • londonbairn
    Automated Home Jr Member
    • Dec 2015
    • 13

    Originally posted by DBMandrake View Post
    Assuming you still have the same problem after a replacement unit it might pay to start your own thread with a description of the problem.

    Chances are that "for no reason" is not the case and it's more a case of understanding how the system works. (Or possibly a comms fault causing failsafe mode to activate, if you have failsafe enabled - I had that happen when I had an incorrect binding causing the boiler to run at 20% duty cycle over night warming up the rooms with manual TRV's)

    One example of "coming on for no reason" would be turning the heating "off" and then seeing the boiler relay come on a couple of minutes later for a couple of minutes - due to the way communications work this can and does happen.
    Random on/off was easy to fix. Embarrassingly we had a savvy visitor who over rode one of the TRVs in a spare room. Shame the app doesn't show you when this happens!

    Battery issue not so easy to fix. Needs a whole new unit sadly. Apparently been a batch with problems..

    Comment

    • DBMandrake
      Automated Home Legend
      • Sep 2014
      • 2361

      Originally posted by londonbairn View Post
      Random on/off was easy to fix. Embarrassingly we had a savvy visitor who over rode one of the TRVs in a spare room. Shame the app doesn't show you when this happens!
      Aha, that explains it. Yes I agree, not showing an HR92 override on the main controller is a big oversight, and leads to much head scratching when a room refuses to fall in temperature as expected despite apparently being set to 5 degrees...

      The good news is that with the firmware update discussed earlier in this thread this issue is resolved - an HR92 local override is now shown on the main controller and smartphone app as a timed override just as if it had been entered from the controller or smartphone app. This is much better IMO.
      Battery issue not so easy to fix. Needs a whole new unit sadly. Apparently been a batch with problems..
      That's a bummer. My first guess would have been bad batteries - it just runs off two standard AA NiMH rechargeable batteries behind the front panel, but if they say there is a bad batch of controllers then I guess you're best to get it swapped under warranty rather than messing around with trying different batteries.
      Last edited by DBMandrake; 23 December 2015, 11:01 PM.

      Comment

      • chippie
        Automated Home Lurker
        • Dec 2015
        • 5

        I tried sending a message to get the firmware update, but got the following response:

        Unfortunately we cannot provide you with an firmware update. When a update is available it will be installed by your installer. I advise to get in contact with them.

        Is there any way to get the upgrade? The case ref for the contact is 12609129.

        Comment

        • londonbairn
          Automated Home Jr Member
          • Dec 2015
          • 13

          Swap is coming tomorrow. Is there a way to copy our configuration over to new unit or will have to start afresh?

          Comment

          • jneaum
            Automated Home Lurker
            • Dec 2015
            • 2

            Originally posted by DBMandrake View Post
            Aha, that explains it. Yes I agree, not showing an HR92 override on the main controller is a big oversight, and leads to much head scratching when a room refuses to fall in temperature as expected despite apparently being set to 5 degrees...

            The good news is that with the firmware update discussed earlier in this thread this issue is resolved - an HR92 local override is now shown on the main controller and smartphone app as a timed override just as if it had been entered from the controller or smartphone app. This is much better IMO.

            ..... but if they say there is a bad batch of controllers ......
            If there really has been a bad batch of controllers, Honeywell should know the Device IDs affected and it would be good if they recalled the bad and provided good.

            Comment

            • londonbairn
              Automated Home Jr Member
              • Dec 2015
              • 13

              I imagine it was just the batteries (I did say would be happy with replacement ones) but Honeywell said to change it all

              Comment

              • benc
                Automated Home Lurker
                • Sep 2015
                • 7

                Based on another thread I decided to check if my wifi controller has been updated with the latest firmware, and I'm very happy to say it has! I tested the manual override and sure enough it now displays on the controller and app. Very nice!

                I've been suffering temperature overshoots in some rooms (by up to 3 degrees) which I am putting down to oversized rads for the size of room. It's a pain, but I'm getting around it by adjusting the radiator temperature controller on the boiler to coincide with cold/warm spells in the weather. And I have throttled the flow to the rads in the problem rooms by adjusting the lockshields which has helped a bit. I'll be interested to see if the new firmware helps with this overshoot at all.

                Comment

                • rotor
                  Automated Home Guru
                  • Aug 2015
                  • 124

                  I have overshoots as well, and I don't understand why. Surely each HR92 is supposed to be learning the room, and should know that the radiator is too big, and should therefore restrict flow?

                  Comment

                  • Evo
                    Automated Home Lurker
                    • Nov 2015
                    • 8

                    I assume it is just the controller that is wifi? I assume th rad valves tec are not?

                    Any changes in the GUI or functions from the screen?

                    Cheers

                    John

                    Comment

                    • DBMandrake
                      Automated Home Legend
                      • Sep 2014
                      • 2361

                      Apart from a slightly bolder font in some places I haven't noticed any visible changes in the GUI.

                      Comment

                      • benc
                        Automated Home Lurker
                        • Sep 2015
                        • 7

                        I did notice that you can now clear errors from the logs. I think that's new?

                        It hasn't done anything for my overshoots. Still going over by 2 degs in some rooms.

                        Comment

                        • The EVOHOME Shop
                          Site Sponsor
                          • Dec 2014
                          • 483

                          Originally posted by benc View Post
                          It hasn't done anything for my overshoots. Still going over by 2 degs in some rooms.
                          Originally posted by rotor View Post
                          I have overshoots as well, and I don't understand why. Surely each HR92 is supposed to be learning the room, and should know that the radiator is too big, and should therefore restrict flow?
                          Based on the fact that the heating load for each room should be individually 'designed' and 'calculated' on worst case scenario (circa 75 degrees Celsius flow temp at -4), guestimating by oversizing radiators without then reducing the designed flow temperature would in my opinion be very hard for a HR92 to control the system 100%.

                          I think for the cost of these items, they do a very good job indeed. There are just too many factors and variables involved in most people heating systems (outside of the control of the HR92) for them to be perfect. If you do want perfection, when the HR92's were installed the radiators should have been replaced with ones correctly sized, the heating system flushed and the radiator valves replaced - maybe even the boiler replaced if this is oversized too.

                          The HR92's in conjunction with the evohome Controller does learn and maximise what you have got to the best of their ability (this can take a while) - but they can't do miracles.

                          I would suggest lowing the flow temperature of your boiler (if possible bearing in mind heating systems with hot water cylinders need to be at no lower than say 68 degrees flow temp) or balancing the heating system correctly to ensure the HR92's have the best chance of controlling the rooms they are in.

                          Any chance of some pictures of these HR92's and the locations they are fitted in?

                          Comment

                          • paulockenden
                            Automated Home Legend
                            • Apr 2015
                            • 1719

                            If you have rooms that overshoot one simple thing is to reduce the flow by closing the lockshield valve (other end from the HR92) slightly. Not a perfect solution, but it might help. But you're never going to reduce the thermal mass of a large radiator. Unless, perhaps, you deliberately let it half-fill with air (where you'd normally bleed it).

                            Comment

                            • The EVOHOME Shop
                              Site Sponsor
                              • Dec 2014
                              • 483

                              Originally posted by paulockenden View Post
                              If you have rooms that overshoot one simple thing is to reduce the flow by closing the lockshield valve (other end from the HR92) slightly. Not a perfect solution, but it might help. But you're never going to reduce the thermal mass of a large radiator. Unless, perhaps, you deliberately let it half-fill with air (where you'd normally bleed it).
                              Did you just say let the radiator fill with air Paul? If you want to promote system wide corrosion and all lol...

                              Comment

                              • DBMandrake
                                Automated Home Legend
                                • Sep 2014
                                • 2361

                                I too would like to see a detailed description of the setup of the rooms where the overshoots are occurring.

                                At the end of the day the system can't work miracles if you have a large radiator with a large thermal mass, a high flow temperature, and (probably) a system where none of the radiators have been balanced. If the room is well insulated it would tend to make overshooting even worse.

                                Our loft-conversion bedroom radiator is massively over spec'ed (by previous owners I hasten to add) and is a Type 22 of approximately 1200x750mm... Needless to say if the boiler is already up and running and I open the TRV fully for just the one minute that it takes for the radiator to fully heat and then immediately close it again, the room will suffer about a 3 degree overshoot past the previous temperature over a period of about 15 minutes purely due to the thermal inertia of the hot radiator still putting out heat...and it then take a long time to cool down.

                                This kind of lopsided thermal response is what the HR92 has to try to deal with. The only way it can heat the room up quickly but without overshooting the target in such a situation is learn by trial and error how much overshoot there is and calculate how much earlier than the target temperature it should shut the valve so that the room temperature coasts towards the target as the radiator cools. (It actually progressively closes it as the target is approached but the principle is the same)

                                The problem with this is that it is a delicate balance that is affected by other variables outside its control like - is the window open ? Is the door open ? Is the radiator partially or completely covered by clothes or towels ? The HR92 doesn't know... it only sees the end result of that after the fact when the temperature doesn't change in the way it anticipated, but it doesn't know why it didn't as it is not sentient.

                                In our bedroom if I keep the window and door closed and put no clothes/towels on the radiator then despite the massive thermal mass of the radiator after a single day of a 2-3 degree overshoot it will get it pretty much on the dot the following day after observing the previous days overshoot and learning from it.

                                However if I then cover the radiator with a towel the following day the room might overshoot by 2 degrees or so due to the slower release of heat from the radiator into the room, which upsets that delicate balance that it was maintaining. If I leave a towel on it every day it will quickly adapt (a couple of days typically) and now reach the target without overshoot. If I then remove the towel the following day it will undershoot for a day or two! Clearly it is learning and adapting the best it can with the information it has available to it.

                                The more oversized the heat output of the radiator is the more "unstable" this balance will become. If the radiator was a bit smaller, or the flow temperature was lower then the system becomes less unstable and it doesn't have to rely so much on predictively turning the radiator off early to prevent overshoot.

                                In our living room we have three radiator panels approx 600x600 each (double skin, no fins, yes they are antiquated) mounted around a bay window piped together as one, controlled by one HR92. Normally there is a chair in front of the middle one. Again this may be a bit oversized as it can manage a temperature increase in the room of about 6 degrees an hour at a flow temperature of 70 degrees, and that's with the lockshield valve balanced as well...

                                Despite this day after day it heats up quickly without overshooting and maintains an almost flat line all evening. The day we replaced the chair with a Christmas tree (a real one) and moved the chair to obscure the 3rd panel instead of the middle one, we had a big overshoot of about 2 degrees for the first couple of days but it quickly adjusted and started hitting it's targets again. Then when the tree was removed it undershot for a day or so. Again, learning, and quickly!

                                Based on how I've seen my system perform, I don't believe that it would overshoot day after day unless the heat output of the radiators was massively over rated and therefore inherently an "unstable" system from a system control point of view, or other variables were changing every day, so that it never had a steady situation to adapt to. For example doors being left open sometimes, closed others, windows the same, TV on sometimes, off other times, (a TV is a source of heat) number of people in the room changing etc.

                                It's easy to forget that all sources of heat in a room count. Our living room comes up to temperature before we get home and usually the door is left closed so it reaches a very steady equilibrium with no overshoot. As soon as we put the TV on and settle on the sofa there is typically a half degree overshoot - simply due to the heat output of two people and a TV set...and it takes a little while for it to adjust to this, which it does.

                                The temperature of adjacent rooms is also a factor, and one that I think the evohome does not take into account. If your living room always tries to heat to 21 degrees at 6pm but sometimes the hallway is hot at this time and sometimes it is not, then the anti-overshoot adaption would be thrown out a bit. (Obviously if the door between them is sometimes left open and sometimes not, that is also a big factor)

                                In the case of a really oversized radiator, throttling down the lockshield valve a bit (measured with an IR gun at each end of the radiator) may help - it seems that balancing a system is a lost art in the days of TRV's, a lot of "heating engineers" just leave the lockshield valves fully open...
                                Last edited by DBMandrake; 14 January 2016, 01:02 PM.

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