Ideal Vogue & Opentherm via Honeywell T6 Lyric (wired version)

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  • paulockenden
    Automated Home Legend
    • Apr 2015
    • 1719

    #31
    I realise this is a side issue, but I'm struggling to see the logic of allowing OpenTherm to control the pump speed.

    Surely on a boiler with an integral pump, the boiler knows best what pump speed is needed in order to maintain a given flow rate? The thermostat simply needs to say "I need flow at 48 degrees" or whatever.

    What leads you to believe that control of pump speed is an issue here?

    I reckon, PERHAPS, although the boiler can modulate down to 30 degrees, maybe it's reporting back across opentherm that it'll only go down to 45. Which then forces the Lyric into "low load" mode below that value.

    So perhaps the bug isn't what it can do, rather what it SAYS it can do.

    You'd need something like this to debug what's going in.

    But can't help wondering whether the pump speed thing is a red herring.

    P.

    Comment

    • richardc1983
      Automated Home Sr Member
      • Nov 2016
      • 86

      #32
      Originally posted by paulockenden View Post
      I realise this is a side issue, but I'm struggling to see the logic of allowing OpenTherm to control the pump speed.

      Surely on a boiler with an integral pump, the boiler knows best what pump speed is needed in order to maintain a given flow rate? The thermostat simply needs to say "I need flow at 48 degrees" or whatever.

      What leads you to believe that control of pump speed is an issue here?

      I reckon, PERHAPS, although the boiler can modulate down to 30 degrees, maybe it's reporting back across opentherm that it'll only go down to 45. Which then forces the Lyric into "low load" mode below that value.

      So perhaps the bug isn't what it can do, rather what it SAYS it can do.

      You'd need something like this to debug what's going in.

      But can't help wondering whether the pump speed thing is a red herring.

      P.
      Your possibly right, the boiler knows what it needs to do. Ideal are saying the boiler should be saying it can go down to 30C but we know this isnt happening as the boiler is cutting out at 45C and low load control shows up even though it is turned off in the lyric.

      Comment

      • HenGus
        Automated Home Legend
        • May 2014
        • 1001

        #33
        Originally posted by richardc1983 View Post
        Your possibly right, the boiler knows what it needs to do. Ideal are saying the boiler should be saying it can go down to 30C but we know this isnt happening as the boiler is cutting out at 45C and low load control shows up even though it is turned off in the lyric.
        I wish someone from Honeywell would comment as it makes Evohome/Opentherm something of a non starter if the two key components are connected but not communicating properly. It makes me wonder whether Evohome will work as Honeywell intended with an Ideal boiler?

        Comment

        • paulockenden
          Automated Home Legend
          • Apr 2015
          • 1719

          #34
          If you're handy with a soldering iron, another option is https://www.kiwi-electronics.nl/opentherm-gateway-kit

          Which is the hardware for http://otgw.tclcode.com/otmonitor.html

          P.

          Comment

          • richardc1983
            Automated Home Sr Member
            • Nov 2016
            • 86

            #35
            Originally posted by HenGus View Post
            I wish someone from Honeywell would comment as it makes Evohome/Opentherm something of a non starter if the two key components are connected but not communicating properly. It makes me wonder whether Evohome will work as Honeywell intended with an Ideal boiler?
            Ideals emails today:



            Hi Richard



            The PCB is being delivered to this address already as this is where the boiler has been registered to.

            We are trying to resolve the only potential cause of the issue from our side of things. If this does not resolve the issue then this cannot be the boiler at fault so we would not be able to assist any further.

            I have done all that I can on this by getting you a new PCB and BCC.

            Hopefully this should resolve matters

            Paul Griffith

            Installer Support Team

            -------------------------------------------------------

            HI Richard



            The R&D team have stated the boiler will modulate down to the set point of 30 degrees.

            The query was taken to the highest person in R&D who tested a Vogue boiler on a rig and found that it will operate at 30c.

            They are confident it is not the boiler at fault however I spoke with my manager and we are willing to give you a PCB still as we promised.

            I have ordered up a new PCB and BCC which should be with you by the end of the week.



            Hopefully the new PCB and Bcc will resolve this as this is the only component in the boiler that could potentially cause the issue, however it is more likely to be an external factor.

            If this does not resolve the problem then I’m afraid It would be an issue you need to pursue with Honeywell or your heating engineer.





            Paul Griffith

            Installer Support Team

            Comment

            • DBMandrake
              Automated Home Legend
              • Sep 2014
              • 2361

              #36
              Originally posted by paulockenden View Post
              I realise this is a side issue, but I'm struggling to see the logic of allowing OpenTherm to control the pump speed.

              Surely on a boiler with an integral pump, the boiler knows best what pump speed is needed in order to maintain a given flow rate? The thermostat simply needs to say "I need flow at 48 degrees" or whatever.
              I was thinking the EXACT same thing before I turned the page and saw your reply...

              I can't see how an OpenTherm controller like an Evohome could have the knowledge or visibility into the situation in the boiler it would need to make a meaningful decision on the pump speed - the boiler itself (with an integrated pump) is best placed to make this determination. If the Evohome was allowed to do this there is too much chance of it making a bad decision as it doesn't know enough about the properties of the boiler.

              Although OpenTherm may provide the option to specify a pump speed I think it's value may be marginal. All you really want is OpenTherm to say "boiler on please, provide a flow temperature of 45 degrees" and then it's the responsibility of the boiler to do whatever it sees fit to achieve that target, including modulating the burner, cycling the burner off temporarily if it can't modulate low enough, adjusting the pump speed to be optimal based on the flow temperature and hydraulic resistance of the open radiators etc... Like you I don't see what allowing the Evohome to dictate pump speed would gain, and more than likely it would be a retrograde step.

              Comment

              • HenGus
                Automated Home Legend
                • May 2014
                • 1001

                #37
                Originally posted by HenGus View Post
                I wish someone from Honeywell would comment as it makes Evohome/Opentherm something of a non starter if the two key components are connected but not communicating properly. It makes me wonder whether Evohome will work as Honeywell intended with an Ideal boiler?

                I asked Ideal Technical for advice about the Vogue and Opentherm and I got this response:

                Quote: You are able to connect the Honeywell Evo home multi-zoning control via the Open therm connection or you are able to use it on the switched live in .

                The boiler is a system boiler and is unable to prioritise a call for dwh. unquote

                I am not sure that I understand the response to my query about DWH priority. I have had two installers of rival system boilers tell me that when DWH is required, CH can be isolated, and the boiler will react with max set temp, or if the basic 'S' plan is left as it is, then when DHW is required, the boiler will just pump max temp water around both CH and HW.

                My question wasn't really about the connection it was more about the boiler coping with multi-zoning demands.

                Comment

                • richardc1983
                  Automated Home Sr Member
                  • Nov 2016
                  • 86

                  #38
                  New PCB arrived and was fitted. Does exactly the same, wont ramp down below 45C when the request for heat comes through from the T6 you can see the flow temp is at 38C but then within a few minutes its upto 45C and above until the thermostat cycles off.

                  Comment

                  • Rameses
                    Industry Expert
                    • Nov 2014
                    • 446

                    #39
                    Rich

                    (forgive me if I get terms wrong - not my forte) Here is a chart I have taken at random from some of our test sites with Opentherm. You can see our systems do allow for modulation down to lower levels. The Honeywell interface will operate to the limitations of the boiler. I am told that each boiler vendor has different threshold where the low load transitions to on/off. I dont know what the threshold for Ideal is. The example I show is an Integras boiler for example.

                    26degrees.jpg
                    getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own

                    Comment

                    • paulockenden
                      Automated Home Legend
                      • Apr 2015
                      • 1719

                      #40
                      Without an openthem monitor in the middle (see links above) it's going to be impossible to determine on which side the fault lies.

                      Hopefully Ideal will obtain a T6 and have a play.

                      Although having said that, in real-world operation I wonder how many people really need flow temps below 45 degrees.

                      Oh, just a thought - what you're seeing this problem do you have radiators opened up enough to allow the (probably) pretty high flow rate needed to keep the temp of a firing boiler this low, even with the burner turned right down. If your rads are only partly open you'll get a restricted flow which will then cause heat build-up.

                      P.

                      Comment

                      • richardc1983
                        Automated Home Sr Member
                        • Nov 2016
                        • 86

                        #41
                        Originally posted by Rameses View Post
                        Rich

                        (forgive me if I get terms wrong - not my forte) Here is a chart I have taken at random from some of our test sites with Opentherm. You can see our systems do allow for modulation down to lower levels. The Honeywell interface will operate to the limitations of the boiler. I am told that each boiler vendor has different threshold where the low load transitions to on/off. I dont know what the threshold for Ideal is. The example I show is an Integras boiler for example.

                        [ATTACH=CONFIG]915[/ATTACH]
                        Completely agree but Ideal are blaming you guys and then you guys are passing back. The common thing here is Opentherm, its not down to me surely to resolve this and I think Ideal tech guys need to contact honeywell or someone from honeywell make contact with ideal as this was not a cheap off the shelf thermostat nor was the boiler a cheap boiler.

                        Comment

                        • richardc1983
                          Automated Home Sr Member
                          • Nov 2016
                          • 86

                          #42
                          Yeah all rads are fully open.

                          I think most people would need flow temps below 45C to make full use of it and to prevent cycling. The problem is the flow temp is climbing too high rather than running lower. The thermostat then cycles off rather than the the demand being there but the burner being off.

                          Comment

                          • DBMandrake
                            Automated Home Legend
                            • Sep 2014
                            • 2361

                            #43
                            Originally posted by richardc1983 View Post
                            New PCB arrived and was fitted. Does exactly the same, wont ramp down below 45C when the request for heat comes through from the T6 you can see the flow temp is at 38C but then within a few minutes its upto 45C and above until the thermostat cycles off.
                            Originally posted by paulockenden View Post
                            Oh, just a thought - what you're seeing this problem do you have radiators opened up enough to allow the (probably) pretty high flow rate needed to keep the temp of a firing boiler this low, even with the burner turned right down. If your rads are only partly open you'll get a restricted flow which will then cause heat build-up.
                            I was about to say something similar - are we sure the burner in the boiler can modulate that low with a light load ?

                            Just because the boiler PCB will allow the boiler to be commanded as low as 30 degrees by OpenTherm doesn't mean that the actual burner in the firebox can achieve that on a light load such as one or two radiators being open.

                            A modulating burner has a "modulation ratio" - this is how wide the control range is for the burner, or essentially "how low can it go" without having to cycle right off. As an example if you have a modulation ratio of 5 to 1 on a 20kW boiler this means that the lowest heat it can put out with the burner running continuously is 4kW.

                            If it takes only 2kW to heat the water to 30 degrees in the number of radiators you have running then even though it might be trying to target 30 degrees, and have the burner flame turned down as low as it can, this is inevitably going to cause the temperature to keep increasing past 30 degrees, and at some point it will have a threshold where it says "OK, I'm already on minimum burn and I can't keep this temperature down to the target, I just have to switch off for a while".

                            Bear in mind that keeping even several radiators up to 30 degrees doesn't require much heat output in kW because the temperature differential to the room temperature is very low, so you could only achieve this on a boiler with quite a high modulation ratio. Any other boiler is going to overshoot this 30 degree target and have to cycle off for a while, so I reckon this could be your problem.

                            This problem is explained here and shown nicely on a couple of graphs:



                            What kW rating is your boiler ? See if you can find out what it's modulation ratio is.
                            Last edited by DBMandrake; 19 January 2017, 03:33 PM.

                            Comment

                            • richardc1983
                              Automated Home Sr Member
                              • Nov 2016
                              • 86

                              #44
                              The boiler sits with the flame on at 44C for say 10 minutes before the room thermostat goes off. The 44C is the temperature the boiler is being asked to provide which then means it has plenty of time to lower. If I manually run the boiler with a max flow temp of say 35C the boiler will sit like that all night providing 35C flow water.

                              All radiators are fully on.

                              Comment

                              • DBMandrake
                                Automated Home Legend
                                • Sep 2014
                                • 2361

                                #45
                                Ok in that case it won't be what I was suggesting with modulation ratio then, so forget all that.

                                If both Honeywell and Ideal are pointing the finger at each other I guess you are at an impasse!

                                If you still want to get to the bottom of it, or at least figure out which side is to blame you're going to need an OpenTherm protocol debugging device, as Paul was suggesting.

                                Comment

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