Vaillant boiler monitoring - anyone doing it?

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  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    Vaillant boiler monitoring - anyone doing it?

    Having just spent an hour rewiring my S plan+ system so that the Evohome + OT bridge had almost complete control of it, I started thinking of my next project.

    Today I put the Evohome into Away mode and for the longest time the OT bridge gave the boiler a target temperature of 10C, which means OFF. However suddenly for no reason it put the target temperature up to 33C, but because the flow temperature was already 41C in the boiler, the boiler didn't fire up.

    My current setup is
    1. Boiler is now completely controlled via the OT bridge -> VR33 -> Vaillant boiler. I can see varying target flow temperatures being set. And the OT bridge is firing up the boiler too after all the wiring modifications I had to make inside the boiler PCB (i.e. jumper between 3-4, jumper between 7-8)
    2. Heating pump is controlled by the boiler and now I've rewired my system, so that the CH motorised valve opens whenever the pump is running. So effectively I don't have a CH valve any more.
    3. All the radiators besides two towel rails have the radiator controls on them.
    4. I do have the HW kit as well with a HW valve.
    5. One CH zone is UFH with a T87RF sensor and a BDR91 set up as a Zone Valve operating the UFH pump and it's own zone valve.

    I now want to see what the boiler is actually up to. My boiler is up in the loft so visually monitoring it proves difficult. In fact the entire set-up is so silent, I've had to repurpose the old wired room stat to come on when the pump was running, so I knew the heating system was on - doing something!

    Is there anyone who is successfully monitoring a Vaillant boiler? I have quickly built a read only eBus interface. I want to be able to monitor the flow, return, target flow temperatures and flame status. I know I can monitor flow and return via external sensors but would like the boiler's own view.
  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    #2
    Anyone? I used some software called ebus connector and now using something called ebusd. Can see lots of messages but neither software is able to read anything yet.

    Comment

    • bruce_miranda
      Automated Home Legend
      • Jul 2014
      • 2307

      #3
      Several days later and pouring over logs of Hex messages, I am finally at a position where I've got the 4 basic data points that I was looking to measure from my Vaillant boiler i.e. Flow Temperature, Return Temperature, Target Flow Temperature (as set by Opentherm) and Flame Status. Goodness me it was tough going. But without the ebusd software I wouldn't have even started.

      Although I've only actually ever seen a few Target Flow Temperature (as set by Opentherm) on the actual boiler, over a period of a day I saw that the OT bridge used an entire range of temperatures.
      10C, 35C, 40C, 42C, 50C, 55C, 57C, 58C, 59C, 60C, 61C, 62C, 63C, 64C, 65C, 67C, 68C, 69C, 70C, 71C, 72C, 73C, 74C, 75C, 76C, 77C, 79C, 80C, 90C

      10C normally means that everything is shut down and there is no heat demand and 90C is normally when there is HW demand or a lot of CH demand. But it's good to see other temperatures being used too.

      Comment

      • cvenn
        Automated Home Lurker
        • Apr 2016
        • 3

        #4
        Excellent work. Are you planning to get these into Domoticz? I have a Vaillant boiler with VR33 etc. and would love to see what the boiler is doing without having to trek up to the loft room every time.

        Comment

        • bruce_miranda
          Automated Home Legend
          • Jul 2014
          • 2307

          #5
          My Vaillant boiler's flow set to 70C max and the Opentherm target flow for today.

          Boiler Flow.jpg
          Last edited by bruce_miranda; 16 November 2016, 12:15 AM.

          Comment

          • cvenn
            Automated Home Lurker
            • Apr 2016
            • 3

            #6
            Do you know if this data would be available via an HGI80, or does it need the direct eBus interface?

            Comment

            • bruce_miranda
              Automated Home Legend
              • Jul 2014
              • 2307

              #7
              That's actually a good question. The HGI80 should know about anything the evohome system is doing. So if we assume the evohome controller is passing a target value to the OT bridge to pass on to the boiler then it should be available on the HGI80. I know that the OT bridge is being constantly feed the flow and return temperatures by the boiler. But it it passes this information back to the controller I don't know.
              For the moment I took the easiest route. I am taking the data directly from the ebus by listening to the communication between the VR33 and the boiler.

              Comment

              • jdp80
                Automated Home Jr Member
                • Mar 2016
                • 38

                #8
                Hey Bruce,
                I have a vaillant 637 system boiler. I bought an ebus-USB converter from a company in Germany and am using it, via a Raspberry PI, to monitor flow + return temperatures along with modulation setting, flame/pump/demand flags, pressure and error reporting. It's worked very reliably so far. I'm not using Opentherm - yet.

                I wrote a Python script to poll the values via ebusd and log them, with more frequent logging when the boiler is on - these values are uploaded into Domoticz, along with the information from the HGI80 so I can see everything in one place.

                Comment

                • bruce_miranda
                  Automated Home Legend
                  • Jul 2014
                  • 2307

                  #9
                  I'm logging to both Domoticz and also to Emoncms. I haven't worked out how to graph multiple temperatures on a single graph yet in Domoticz, hence I use the Emoncms.

                  Comment

                  • bruce_miranda
                    Automated Home Legend
                    • Jul 2014
                    • 2307

                    #10
                    Originally posted by jdp80 View Post
                    Hey Bruce,
                    I have a vaillant 637 system boiler. I bought an ebus-USB converter from a company in Germany and am using it, via a Raspberry PI, to monitor flow + return temperatures along with modulation setting, flame/pump/demand flags, pressure and error reporting. It's worked very reliably so far. I'm not using Opentherm - yet.
                    If you bought one of the ebus-usb converters that you should be able to tell the boiler what flow temperature you need. You may not even need Opentherm. You could use Domoticz to set the flow temperature based on the heat demand that you see coming via HGI80 and other variables. For me unfortunately, I built a very simply read only interface, so I can only listen to what the boiler is saying. I have to rely on the OT bridge doing the best job. Now that I've watched it for two days I don't like the fact that the OT bridge runs quite a lot at full wack 90C too often.

                    Comment

                    • jdp80
                      Automated Home Jr Member
                      • Mar 2016
                      • 38

                      #11
                      I'm exporting from domoticz into InfluxDB, which can be read by Grafana - great for graphing.

                      Originally posted by bruce_miranda View Post
                      If you bought one of the ebus-usb converters that you should be able to tell the boiler what flow temperature you need. You may not even need Opentherm. You could use Domoticz to set the flow temperature based on the heat demand that you see coming via HGI80 and other variables. For me unfortunately, I built a very simply read only interface, so I can only listen to what the boiler is saying. I have to rely on the OT bridge doing the best job. Now that I've watched it for two days I don't like the fact that the OT bridge runs quite a lot at full wack 90C too often.
                      Yes, I can set flow temps via the interface - that was another reason for getting it. Although, I haven't pursued this yet - I'm not entirely sure what algorithm to use, and wasn't sure whether it would conflict with Evohome's TPI. It's on the list though!

                      Comment

                      • bruce_miranda
                        Automated Home Legend
                        • Jul 2014
                        • 2307

                        #12
                        Infact to start with an extremely simple algorithm would do too. The the TPI can just control the boiler on/off. All you need to do is sense when there is HW demand and make the target flow over 65C, everytime else it can be in the 50s. Or maybe track the return temp and make sure the flow allows for maximum condensation.

                        Comment

                        • paulockenden
                          Automated Home Legend
                          • Apr 2015
                          • 1719

                          #13
                          Flow temp is important. If it's too low and you divert it to the HW tank it'll actually EXTRACT heat!

                          Comment

                          • bruce_miranda
                            Automated Home Legend
                            • Jul 2014
                            • 2307

                            #14
                            Hence why I said the key thing is to sense HW demand and then raise the flow temperature to above 65C, rest of the time it can stay in the 50s.

                            Comment

                            • jdp80
                              Automated Home Jr Member
                              • Mar 2016
                              • 38

                              #15
                              DHW is easy to sense - CH %age seems a bit trickier based on what sensors I currently have in Domoticz - I'm sure there was a CH aggregated value somewhere, maybe it's dropped off.

                              Still a bit fuzzy in my head how I would translate CH heat demand into flow temperature though, guess it would need to learn somehow (outside temperature would be an factor) rather than use arbitrary values

                              I also have UFH in some rooms which would need to be factored in

                              Comment

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