Vaillant boiler monitoring - anyone doing it?

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  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    #16
    Within Domoticz if you check the values of the devices "DHW Valve" and "CH Valve", it appears to show you the aggregated heat demand of both. Based on that just simply change the Target Flow temperature with DHW Valve taking priority. I think this will give you a better Opentherm implementation especially if the boiler switch on is still being controlled by the BDR91 Boiler relay.
    You don't need to bother about outside temperature actually. It's the temperature inside the house that is of more importance.
    Last edited by bruce_miranda; 17 November 2016, 10:48 AM.

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    • bruce_miranda
      Automated Home Legend
      • Jul 2014
      • 2307

      #17
      The more I look at the data, the more I am convinced that a better OpenTherm algorithm could be written especially if you have the ability to read the CH Valve and DHW Valve devices in Domoticz. I bet the OT bridge is simply using these aggregated values to determine what Target Flow to set for the boiler. So if I was doing this again, I probably wouldn't spend money on the OT bridge or the VR33 and would simply buy an eUSB interface and get that hooked up to Domoticz. It appears dead easy and no complex calculations are needed because all that is already being done by the controller and sending that information. If you have the Boiler relay then On/Off is sorted too. Ofcourse if my Domoticz went pop, then things would still work because the Boiler Relay is being controlled by evohome, except that I would lose the ability to vary the Flow temperature and that would mean I go back to a traditional setup.

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      • jdp80
        Automated Home Jr Member
        • Mar 2016
        • 38

        #18
        The only thing is BDR91 boiler controller will do TPI won't it? Does it still do TPI when connected via Opentherm?

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        • bruce_miranda
          Automated Home Legend
          • Jul 2014
          • 2307

          #19
          Originally posted by jdp80 View Post
          The only thing is BDR91 boiler controller will do TPI won't it? Does it still do TPI when connected via Opentherm?
          That's true. You could go the whole way and get your ebus interface to fire the boiler up too based on a Domoticz trigger/condition. That way you get maximum return for your investment in the ebus interface. You just have to mimic the ebus commands fired by the VR33 but with your own target temperature and on/off time.

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          • jdp80
            Automated Home Jr Member
            • Mar 2016
            • 38

            #20
            I've set up some Domoticz logging to track the percentage demand on each 'circuit' to see how they correlate with the boiler flow/return and gas consumption



            It looks like the boiler does a pretty good of modulating down once the flow/return temperatures start to equalise. I'm not sure without a bit more analysis on how I could improve on that.

            Although, it has been quite cold today, maybe there would be more of difference on a day where the outside temperature was in the 10s.
            Will continue to monitor..

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            • bruce_miranda
              Automated Home Legend
              • Jul 2014
              • 2307

              #21
              You are absolutely right. In fact I see the boiler modulating more than the OT. So most of the time the boiler is switching the flame on and off while the OT bridge is just telling the boiler to stay fired up. For me the bit I don't like is the amount of time the OT is telling the boiler to run at full when there is only CH demand. That's where I think a better OT implementation is possible.

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              • bruce_miranda
                Automated Home Legend
                • Jul 2014
                • 2307

                #22
                BTW what are you using to produce those comparative graphs. My Domoticz is only able to graph temperature sensors and nothing else. My CH and DHW Valves and other relays are all listed under switches which means that I cannot add them to my custom graphs.

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                • jdp80
                  Automated Home Jr Member
                  • Mar 2016
                  • 38

                  #23
                  Yeah it's annoying that, it looks like the percentage goes into a different bucket you can't graph.
                  I created some dummy utility sensors then update them in a timed Lua script like
                  Code:
                  value = tostring(otherdevices_svalues['CH Valve'] / 2);
                  commandArray[1] = {['UpdateDevice'] = '[I]<deviceId>[/I]|0|' .. value}
                  279 being the ID of my dummy 'percentage' utility device

                  ..and also post it into InfluxDB for visualisation in Grafana

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                  • bruce_miranda
                    Automated Home Legend
                    • Jul 2014
                    • 2307

                    #24
                    How and what are you using to measure gas consumption?

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                    • jdp80
                      Automated Home Jr Member
                      • Mar 2016
                      • 38

                      #25
                      A Loop energy monitor with pyloopapi

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                      • bruce_miranda
                        Automated Home Legend
                        • Jul 2014
                        • 2307

                        #26
                        That reminds me, I must build myself a gas meter monitor. Would have bought the loop myself had they not forced the electric meter monitor on me. Off to the market now to buy an IR reflector. Let's hope the walk to China doesn't take long.

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                        • DBMandrake
                          Automated Home Legend
                          • Sep 2014
                          • 2361

                          #27
                          Originally posted by bruce_miranda View Post
                          That reminds me, I must build myself a gas meter monitor. Would have bought the loop myself had they not forced the electric meter monitor on me. Off to the market now to buy an IR reflector. Let's hope the walk to China doesn't take long.
                          You don't actually have to use the electricity monitor though ? The dual fuel kit is £60 - if that is still cheaper than other options that do gas only (and it seems to be a lot cheaper than the next nearest competitor as far as I can see) then there is nothing to stop you just buying the dual fuel kit and just not setting up the electricity sensor clamp ? (Or just don't clamp it to anything)

                          For that matter even if you are monitoring the electricity some other way there is no reason you can't fit the clamp in addition to your other method of monitoring. It might even be interesting to see the comparison between the two.

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                          • bruce_miranda
                            Automated Home Legend
                            • Jul 2014
                            • 2307

                            #28
                            Many of the electricity monitors don't work well when you have solar, hence I built one myself and the readings are pretty close to my meter readings. I dont want to spend 60 and then find out that I have range issues etc. I have a ton of wifi enabled mp chips sitting doing nothing, so might as well make this a fun project.

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                            • DBMandrake
                              Automated Home Legend
                              • Sep 2014
                              • 2361

                              #29
                              Fair enough. Range to the gas sensor is certainly a concern - I did have some problems there, but I have got 3 bars now with the right location for the receiver. The problem with adjusting the receiver location is you have to move it and then wait at least 15 minutes for it to check in before the signal reading updates - which can be frustrating if it currently reports no signal...

                              At least the sensor does store up to 30 days worth of data even if it has lost the connection - so when I have had an issue as soon as its fixed it "catches up" the old data so no data is ever lost. I had an issue with my router that was causing no data to go through to loop for a couple of hours - after I rebooted the router it took about 20 minutes to catch itself back up again.

                              As far as accuracy of the gas sensor goes - it has been excellent. After a full weeks use and including mucking around with adjusting for lost signal etc I checked how closely the reading matched my meter last night (after turning the heating off for 20 minutes to let the reading catch up) and the reading was only two out on the very last red digit (it read 2 higher than the meter) which is excellent. I don't seem to have had any problems with light entering the boiler cupboard when the door is opened giving false readings either.

                              So as far as gas readings are concerned I'm pretty happy.

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