OpenTherm control behaviour

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  • kimber.kimber
    Automated Home Sr Member
    • Jan 2017
    • 89

    #76
    I'll have a try of that on the weekend. No reply from Ideal yet. I wonder if there is a hidden menu enabled with the ideal when the OpenTherm is on.

    On the plus side the gas bill is still falling.

    IMG_6962.jpg

    Comment

    • kimber.kimber
      Automated Home Sr Member
      • Jan 2017
      • 89

      #77
      So when I got up this morning I managed to catch the boiler running the system flat out. Temp on the front was running around 80 degrees, despite the max temps being set to 50 on the knob and 60 in the installer menu.

      It would appear that the boiler is together by full control to the evohome unit to call for as much heat as it wants during OpenTherm control. This would appear to be max when the system is first started, but then modulates down when the system is up to temperature.

      If I don't hear back from Ideal today, I'll stick a call into them.
      Last edited by kimber.kimber; 25 April 2017, 10:01 AM.

      Comment

      • GarforthGasServices
        Automated Home Lurker
        • Apr 2017
        • 4

        #78
        Originally posted by kimber.kimber View Post
        So when I got up this morning I managed to catch the boiler running the system flat out. Temp on the front was running around 80 degrees, despite the max temps being set to 50 on the knob and 60 in the installer menu.

        It would appear that the boiler is together by full control to the evohome unit to call for as much heat as it wants during OpenTherm control. This would appear to be max when the system is first started, but then modulates down when the system is up to temperature.

        If I don't hear back from Ideal today, I'll stick a call into them.
        Looks to md like you havent correctly enabled opentherm on the boiler. Usually on the vogue when it is enabled the flow temperature knob is only used to select the appropriate heating curve. i.e you cannot select the flow temperature manually anymore with opentherm enabled.

        It is only correctly enabled when the connector in the front panel is connected to the loose lead behind the pcb cover panel.

        Comment

        • kimber.kimber
          Automated Home Sr Member
          • Jan 2017
          • 89

          #79
          Originally posted by GarforthGasServices View Post
          Looks to md like you havent correctly enabled opentherm on the boiler. Usually on the vogue when it is enabled the flow temperature knob is only used to select the appropriate heating curve. i.e you cannot select the flow temperature manually anymore with opentherm enabled.

          It is only correctly enabled when the connector in the front panel is connected to the loose lead behind the pcb cover panel.
          Hi,

          This is news to me! The installer manual, only talks about whether you are connecting a 230v controller or an OpenTherm (PELV) device. Is the connection you mention unique to the Vogue 1 or the combi?

          There is also no talk about being able to select the different heating curves.

          Am I missing something?

          Comment

          • kimber.kimber
            Automated Home Sr Member
            • Jan 2017
            • 89

            #80
            Found a video describing what you mention, but the Gen 2 appears to be different. There is no additional connection inside the control panel. See image...

            IMG_6968.jpg

            Thanks for the thought though.

            Comment

            • GarforthGasServices
              Automated Home Lurker
              • Apr 2017
              • 4

              #81
              Sorry, that'll teach me for not reading the whold thread ! Didnt realise you were on GEN2.

              The correct answer is almost the same though. You dont have any control over the flow temp as it is calculated by the opentherm controller and the algorithms used to calculate the heat needed. The button may as well be removed.

              Comment

              • kimber.kimber
                Automated Home Sr Member
                • Jan 2017
                • 89

                #82
                That's ok, too easily done on a forum! There are 9 pages now after all!

                You mention being able to choose the algorithm on a gen 1. Can you do this on the Gen 2
                Last edited by kimber.kimber; 25 April 2017, 09:09 PM.

                Comment

                • GarforthGasServices
                  Automated Home Lurker
                  • Apr 2017
                  • 4

                  #83
                  I'm not sure about Gen2. To be honest the support from ideal is poor both in terms of documentation and from the tech rep.

                  I'm able to set the heat curves on the gen 1 but havent had chance to get near an OT gen2 as yet.

                  You cant change the opentherm algorithms, but im not sure if thats what you really mean, I'm thinking you are more interested in getting more control of the boiler parameters, but this would not be a good idea as you may counteract what the opentherm controller is trying to achieve ?

                  Comment

                  • kimber.kimber
                    Automated Home Sr Member
                    • Jan 2017
                    • 89

                    #84
                    Sorry I meant heat curves, not algorithms. My bad!

                    Comment

                    • kimber.kimber
                      Automated Home Sr Member
                      • Jan 2017
                      • 89

                      #85
                      Still no reply from Ideal. Going to try and give them a ring tomorrow to chase.

                      Comment

                      • kimber.kimber
                        Automated Home Sr Member
                        • Jan 2017
                        • 89

                        #86
                        Just had a reply from Ideal. This is my initial email...

                        Hi

                        I've just had a Vogue S32 system installed. The boiler is being controlled by a Honeywell Evohome control system, with TRVs on all of the radiators and an automatic bypass valve. I'm using the Honeywell OpenTherm module to control the boiler.

                        The slightly odd thing is that the boiler maximum flow temperature keeps being surpassed. Currently the boiler has the maximum flow temperature at 60 degrees, yet its showing a flow temperature of 75.

                        Also, when there is very little demand on the boiler, is keeps cycling the flame for very short durations. This can be see in the following video;



                        Is this normal?

                        Many thanks,

                        Ian


                        And the reply from Ideal...


                        Hi Ian,

                        From the video the boiler is working as it should, it will short cycle when close to a set temperature to keep the flow as close to this as possible.

                        The set temperature for the flow on the front of the boiler is over ridden by the open-therm controls which will increase or decrease the flow temp due to room temperature etc.

                        I hope this helps

                        regards

                        Richard Maskell
                        Domestic Technical Team Manager


                        I've now gone back Ideal with the following...


                        Richard,

                        Thanks for coming back to me. The main issue I am seeing is that without temperature control of the boiler, the boiler is running at 80 degrees at initial load, which is then causing overshoots in room temperatures and can make it uncomfortable. It does throttle back to 50 degrees when load is satisfied, but it takes a while. Is this what you would expect? Is there any downside to the boiler running at it's maximum operating temp for periods of time? I should point out that I do not have the hot water enabled yet, as I am still completing the switch over.

                        I was under the impression that the previous generation boiler has the ability to control the heat curves and therefore the flow temperature. It not only disables the knob, but also the installer menu.

                        Finally the efficiency reading on the boiler is currently very low, at only 30%. This a lot lower than I was expecting, especially running the opentherm module. Could there be any reason for the low efficiency reading?

                        Regards,

                        Ian


                        I'll let you know what comes back.

                        Comment

                        • bruce_miranda
                          Automated Home Legend
                          • Jul 2014
                          • 2307

                          #87
                          Looks like Ideal and Viesmann are sharing notes about how best to implement Opentherm! (Not)

                          Comment

                          • StephenC
                            Automated Home Guru
                            • Feb 2017
                            • 102

                            #88
                            Sounds like we have same problem.

                            @ Rameses - is this something that Honeywell can look at now we are seeing multiple boiler vendors expecting the OT controller to set the max ch flow temp?

                            I note the new Nest v3 seems to have the ability when connected via Opentherm. So appears it is possible from a protocol perspective.

                            Comment

                            • StephenC
                              Automated Home Guru
                              • Feb 2017
                              • 102

                              #89
                              Originally posted by bruce_miranda View Post
                              Looks like Ideal and Viesmann are sharing notes about how best to implement Opentherm! (Not)
                              lol!

                              I'm keeping my R8810 OT Bridge as I'm convinced it's a better solution than Weather Compensation now I've used both. It's just the high temps that make it impossible to use right now. I'll look for a solution.

                              OT is more suited for people who set back zones for example overnight or during the day with high heat loss in the house.

                              Weather Compensation I can say now is better suited to maintaining a constant temp through all day.

                              It's been interesting to observe the different methods and see which could be better in certain situations.

                              Hope this info helps someone out as WC and OT are often compared as being similar (external vs internal sensing and modulation) - but actually, I can now see through experience they are very different.
                              Last edited by StephenC; 27 April 2017, 03:06 PM.

                              Comment

                              • dty
                                Automated Home Ninja
                                • Aug 2016
                                • 489

                                #90
                                Originally posted by StephenC View Post
                                is this something that Honeywell can look at now we are seeing multiple boiler vendors expecting the OT controller to set the max ch flow temp?
                                The interesting thing here will be whether the OT bridge is just a relatively dumb protocol converter (i.e. radio <-> OT) and the brains of the protocol stuff is in the controller, or the brains is in the OT bridge. If *I* were designing it, I would go with the former which would allow changes to the protocol implementation to be done with a controller firmware upgrade. But if it's the latter, then it will only be "fixable" (assuming Honeywell deem it to be an issue on their side and worthy of fixing) by replacing OT bridges - and I doubt Honeywell will do that.

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