Anyone using Domoticz with Evohome OT + Outdoor Temperature + HGI80 (or similar)

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  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    Anyone using Domoticz with Evohome OT + Outdoor Temperature + HGI80 (or similar)

    I just discovered that the Evohome OT Bridge will respond to quite a wide range of OT Commands over its radio.
    One of the more useful bit of information is Outdoor Temperature.
    I am keen for someone who has a natively OT compliant boiler with an Outdoor Temperature sensor connected to test my latest Domoticz change. You will need an HGI80 or similar to test this.
    You will also need to update Domoticz to the latest beta development version.
    I have added a Log message that displays the Outdoor Temperature that I calculated using the data the OT Bridge got from the boiler. I just need to see some of those messages.
    My own boiler is a Vaillant that doesn't support OT but using the VR33 it does allow an OT device to be connected. I can see Outdoor Temperature data being returned. Using that data, I have correlated the data received back to the Temperature by comparing what the Vaillant reports as the Outdoor Temperature and what the OT Bridge is reading.
    But I would like more information before I commit that change. The Evohome controller has, in the past, never queried the Outdoor Temperature. Even when weather compensation was introduced it still didn't retrieve the data from the Boiler. I want to check if there was a reason for that or if Resideo just ran out of time to implement a local sensor based weather compensation, which would have been quite useful.
  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    #2
    No one with this configuration on the forum?

    Comment

    • paulockenden
      Automated Home Legend
      • Apr 2015
      • 1719

      #3
      I used to have, but when I added the pre-heat tank before my Intergas combi I added the special sensor for this, and that seemed to clash with the outside temp sensor, so that got ditched.

      Comment

      • bruce_miranda
        Automated Home Legend
        • Jul 2014
        • 2307

        #4
        I am getting back data from my Outdoor sensor, which seems to change exactly in relation to the actual temperature but I can't make any sense of the data I am getting.
        So I am trying to figure out where the problem might be.
        I am going from Domoticz-> HGI80-> OTB-> VR33-> Outdoor sensor.
        So I have no idea if there is an issue in the VR33s translation between eBUS data to OT data.
        Or that its the OTB that is causing the problem.
        Or my Domoticz implementation.
        Thing is, I am using the same code to query the other boiler parameters and that seems to work fine. But then again, the Evohome never queried the Outdoor Temperature from the OTB before. And maybe, the bug I have stumbled on is the reason why Resideo "ran out of time" to implement Evohome weather compensation using the local boiler's outdoor sensor.

        Comment

        • kevinsmart
          Automated Home Ninja
          • Sep 2018
          • 257

          #5
          Originally posted by bruce_miranda View Post
          I am getting back data from my Outdoor sensor, which seems to change exactly in relation to the actual temperature but I can't make any sense of the data I am getting.
          So I am trying to figure out where the problem might be.
          I am going from Domoticz-> HGI80-> OTB-> VR33-> Outdoor sensor.
          So I have no idea if there is an issue in the VR33s translation between eBUS data to OT data.
          Or that its the OTB that is causing the problem.
          Or my Domoticz implementation.
          Thing is, I am using the same code to query the other boiler parameters and that seems to work fine. But then again, the Evohome never queried the Outdoor Temperature from the OTB before. And maybe, the bug I have stumbled on is the reason why Resideo "ran out of time" to implement Evohome weather compensation using the local boiler's outdoor sensor.
          Stick an OTGW between the OTB and VR33? That should tell you whether the Domoticz->HGI80->OTB path is working, returning the same value.

          We know OTB->Boiler->Outdoor sensor works. The OTB regularly requests the Outside temperature. So if the OTGW is reading a nonsense value it's likely to be your VR33 that is the issue.

          Comment

          • bruce_miranda
            Automated Home Legend
            • Jul 2014
            • 2307

            #6
            Kevin, are you saying you have actually seen the OTB request the outside temperature ID: 1B from the boiler? I wonder why it does that thought. That data is going nowhere. Evohome wasn't pulling it before the latest firmware update and not infact pulls no OT data any more.

            Comment

            • kevinsmart
              Automated Home Ninja
              • Sep 2018
              • 257

              #7
              Originally posted by bruce_miranda View Post
              Kevin, are you saying you have actually seen the OTB request the outside temperature ID: 1B from the boiler? I wonder why it does that thought. That data is going nowhere. Evohome wasn't pulling it before the latest firmware update and not infact pulls no OT data any more.
              Yes, that's right, approximately every 1m 45s. It's not OTGW initiated, it is coming from the OTB (T for Thermostat, B for Boiler):

              00:01:06.465029 T001B0000 Read-Data Outside temperature: 0.00
              00:01:06.777600 B401B0400 Read-Ack Outside temperature: 4.00

              When I first saw this, it was the original motivation behind me modifying the OTGW firmware to support weather compensation.

              Comment

              • bruce_miranda
                Automated Home Legend
                • Jul 2014
                • 2307

                #8
                Very interesting. Could you please show me some more of these temperature messages, especially if you have the actual temperatures too. And definitely when the temperature is above 16C outside.

                Comment

                • kevinsmart
                  Automated Home Ninja
                  • Sep 2018
                  • 257

                  #9
                  From my previous house with Intergas boiler. The Intergas boiler returns fractional temperatures, its sensor was very accurate according to my Netatmo weather station.

                  01:42:24.375260 T001B0000 Read-Data Outside temperature: 0.00
                  01:42:24.471559 B401B04CA Read-Ack Outside temperature: 4.79
                  ...
                  01:43:24.893382 T001B0000 Read-Data Outside temperature: 0.00
                  01:43:25.018012 B401B04D1 Read-Ack Outside temperature: 4.82

                  It was read approximately every 60 seconds.

                  My Vokera sensor is less accurate, always an integer and typically 1C higher than my Netatmo. Seems to be read less frequently. I wonder if this is due to the latest firmware, maybe someone else can confirm.

                  22:11:07.679883 T001B0000 Read-Data Outside temperature: 0.00
                  22:11:07.890209 BC01B0600 Read-Ack Outside temperature: 6.00
                  ...
                  22:12:55.586279 T001B0000 Read-Data Outside temperature: 0.00
                  22:12:55.597772 BC01B0600 Read-Ack Outside temperature: 6.00

                  My current outside temperature is 5.6C. You'll have to wait a few weeks for me to see >16C, I'm in Scotland.

                  Comment

                  • bruce_miranda
                    Automated Home Legend
                    • Jul 2014
                    • 2307

                    #10
                    The Evohome firmware upgrade cannot impact the frequency at which the OTB requests the boiler for the outside temperature. It could however be that the two OTB units that you have, have different OTB firmware versions in them. As I said, the latest Evohome firmware has infact stopped requesting ANY boiler data from the OTB. And it never requested Outside Temperature data. So the fact that the OTB requests that from the Boiler is quite surprising.
                    Your data provided above is super useful.

                    Comment

                    • kevinsmart
                      Automated Home Ninja
                      • Sep 2018
                      • 257

                      #11
                      Originally posted by bruce_miranda View Post
                      The Evohome firmware upgrade cannot impact the frequency at which the OTB requests the boiler for the outside temperature. It could however be that the two OTB units that you have, have different OTB firmware versions in them. As I said, the latest Evohome firmware has infact stopped requesting ANY boiler data from the OTB. And it never requested Outside Temperature data. So the fact that the OTB requests that from the Boiler is quite surprising.
                      Your data provided above is super useful.
                      Bruce, how often does the Evohome controller communicate with the OTB? Maybe that frequency has changed and that influences how often the OTB reads boiler parameters. There are several other requests like return water temperature read at around the same rate.

                      Comment

                      • bruce_miranda
                        Automated Home Legend
                        • Jul 2014
                        • 2307

                        #12
                        So previously, Evohome would request the boiler stats from the OTB every 5mins. It doesn't do that any more. It used to request the Control Setpoint and Flame status every minute, it doesn't do that either.

                        Comment

                        • bruce_miranda
                          Automated Home Legend
                          • Jul 2014
                          • 2307

                          #13
                          My OTGW sat unused for over a year and the moment I decide to sell it, because it made little sense to my setup, I could do with one - Typical isn't it.
                          In any case, what I was trying to do was provide a way for users to see and track Outside temperature. But it looks like the VR33 might be the issue here. It's still worth implementing because looking at the above it shows that on a native OT boiler the data is valid.

                          Comment

                          • kevinsmart
                            Automated Home Ninja
                            • Sep 2018
                            • 257

                            #14
                            opentherm1.JPG
                            opentherm2.JPG

                            Here are all the types of requests seen by my OTGW. You can see there are a bunch of them with a period of around 1m45s.

                            The DHW ones are odd, because Evohome doesn't distinguish between CH and DHW from an OpenTherm control perspective.

                            Most likely the R8810A OTB has been designed to also handle other controllers.

                            I should say though that some of them are inserted by the OTGW. Basically if it knows that an ID is not supported by the boiler it will replace it with an alternative ID to read additional information. Burner operation hours is an example of that, but my boiler just returns 0 for it, the Intergas does provide actual values.
                            Last edited by kevinsmart; 26 February 2021, 03:05 PM.

                            Comment

                            • bruce_miranda
                              Automated Home Legend
                              • Jul 2014
                              • 2307

                              #15
                              That is quite clear evidence that the OTB is doing a lot more than is being instructed by Evohome.

                              Comment

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