Help with Evohome / Opentherm / Intergas

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • The EVOHOME Shop
    Site Sponsor
    • Dec 2014
    • 483

    Originally posted by HenGus View Post
    I have been asking for Honeywell to provide information on normal Evohome/Opentherm operation for the past 6 months. Given that the very essence of Evohome is multi-zoning then it would seem that cranking the boiler up to max flow temperature,when any zone is outwith the 1.5C difference, runs counter to what Opentherm is designed to achieve.

    Exam question: Would better boiler efficiency be achieved with standard TRVs or single zone control (boiler operating under Opentherm control) than with Evohome/Opentherm multi-zoning.? Discuss
    See, now I haven't read anywhere that OpenTherm was 'designed' to do what people have suggested it 'should' (i.e. modulate the boilers burner to the most efficient point at all times). What I have read from the OpenTherm specification sheet is that the thermostat does not tell the boiler how to achieve the 'control setpoint' (that has been set by the thermostat), just like the boiler has no direct influence on what the thermostat(s) themselves do.

    When there is heating demand from one HR92 zone, the boiler will probably go to max designed flow temp set at the boiler (70 degrees C on my Intergas boiler for instance) and this room will heat up. The other rooms will also receive a higher flow temperature, but the HR92's should be putting the brakes on these radiators anyway (so the flow rate into them is minimal).

    Once in the control bandwidth, the boiler will modulate below the designed temp of the system and remain in the lower spectrum of condensing mode which is its most efficient point.

    For me the evohome multi zone system is still the clear winner - to revert backwards would be a mistake (as the control would be effectively removed from the individual zones).
    Last edited by The EVOHOME Shop; 11 August 2017, 04:35 PM.

    Comment

    • paulockenden
      Automated Home Legend
      • Apr 2015
      • 1719

      Originally posted by The EVOHOME Shop View Post
      My personal feeling is that the information on how evohome is supposed to respond to OpenTherm had never been confirmed by Honeywell (no one had asked either), so those 'testing' it were really only guessing and assuming it works similar to TPI control (1.5 degrees proportional band, etc) - it doesn't.
      I asked. Here. And one of the Honeywell guys responded that it DOES work the same as BDR control, with a proportional band etc..

      Found it: http://www.wordpress-1219309-4387497...ll=1#post32858, and the following few comments.

      P.
      Last edited by paulockenden; 11 August 2017, 05:18 PM.

      Comment

      • Dan_Robinson
        Automated Home Ninja
        • Jun 2012
        • 347

        It's a terminology thing.
        Kind Regards - Dan Robinson (Jennings Heating Ltd)

        Comment

        • bruce_miranda
          Automated Home Legend
          • Jul 2014
          • 2307

          Here is what I had said before http://www.wordpress-1219309-4387497...ll=1#post32870 still holds true and will be so with Intergas as well. I have been saying all along that I thought that the Intergas 'issue' was not an issue but the same behaviour as exhibited by all the other boilers. Problem was that NO one on this forum ever spelt out what the Intergas issue was except that @Hengus said that Intergas had confirmed there was a problem. So now there is None. World peace has been restored.

          Comment

          • HenGus
            Automated Home Legend
            • May 2014
            • 1001

            Originally posted by bruce_miranda View Post
            Here is what I had said before http://www.wordpress-1219309-4387497...ll=1#post32870 still holds true and will be so with Intergas as well. I have been saying all along that I thought that the Intergas 'issue' was not an issue but the same behaviour as exhibited by all the other boilers. Problem was that NO one on this forum ever spelt out what the Intergas issue was except that @Hengus said that Intergas had confirmed there was a problem. So now there is None. World peace has been restored.
            Intergas thought that there was an issue. Their reply dated December 2016:

            Many thanks for your email.

            There is no resolution date for the issue with the Eco PCB at present, we are still awaiting any news on that sorry.

            We have no release date for the Extreme boilers but I have been assured that they will be opentherm compatible. As soon as we have a release date for these boilers we will let everyone know.

            Regards

            xxxx xxxx
            Technical Support Engineer



            Intergas Heating Ltd
            Unit 94, Bay 1 Vantage Point
            The Pensnett Estate
            Kingswinford
            West Midlands
            DY6 7FS

            Comment

            • The EVOHOME Shop
              Site Sponsor
              • Dec 2014
              • 483

              Let me ask you a question. If it was middle of winter and the boiler went beautifully into condensing mode but the rooms took 3 hours to achieve target temperature, would you be happy? Or would you prefer them to achieve target temperature at the right time requested and when they are at that temperature to stay at the same temperature efficiently? I am of the opinion that you can't have both of these things with OpenTherm, but the way it works is very clever indeed.

              It seems Viessmann and Ideal have problems with the way they have implemented OpenTherm with some of their boilers. They have chosen to ignore key OpenTherm ID's and Flags and by doing this they are not playing nicely with non-manufacturer controls. The Dutch have been doing OpenTherm for a long time due to the energy efficiency laws out there. Do I think OpenTherm is good?... Yes I do! Do I think there are improvements that can be made to OpenTherm?... Always!

              However, having a control setpoint of 28 degrees C today with my evohome and the pump running and the burner hardly firing, was proof to me I am doing the right thing by promoting Intergas & Honeywell OpenTherm controls over TPI and ON/OFF controls as the best possible solution.

              Comment

              • bruce_miranda
                Automated Home Legend
                • Jul 2014
                • 2307

                @HenGus maybe you should write to Intergas and have them rethink their reply. Especially now that we know for sure there is no issue. :-) Maybe they don't know this too.

                Comment

                • The EVOHOME Shop
                  Site Sponsor
                  • Dec 2014
                  • 483

                  Originally posted by bruce_miranda View Post
                  @HenGus maybe you should write to Intergas and have them rethink their reply. Especially now that we know for sure there is no issue. :-) Maybe they don't know this too.
                  Sadly Bruce I think you will find that they won't care. Intergas UK are not known for their controls knowledge! Why do you think I take these brands on as specialist businesses... I like a challenge!

                  Comment

                  • paulockenden
                    Automated Home Legend
                    • Apr 2015
                    • 1719

                    So, Richard, you said a few messages back that with OpenTherm the 1.5 degree proportional band isn't present (despite Top Brake implying that it is, in a previous thread). So what happens as the zones get close to their setpoints then? How far away from hitting the target do we need to be before OpenTherm starts lowering the boiler flow temperature?

                    It'd be nice to start to get some straight answers!

                    Thanks,

                    P.

                    Comment

                    • Dan_Robinson
                      Automated Home Ninja
                      • Jun 2012
                      • 347

                      1 degree. As I said earlier.
                      Kind Regards - Dan Robinson (Jennings Heating Ltd)

                      Comment

                      • paulockenden
                        Automated Home Legend
                        • Apr 2015
                        • 1719

                        Originally posted by Dan_Robinson View Post
                        1 degree. As I said earlier.
                        So the proportional band is narrower with OT than it is with TPI?

                        That seems completely counter-intuitive to me.

                        But hey, if it works without producing hideous overshoots then great!

                        P.

                        Comment

                        • Dan_Robinson
                          Automated Home Ninja
                          • Jun 2012
                          • 347

                          For a while now I've been saying that if you override Evohome it drops its knickers and panics. Richard confirmed to me that this holds true, and that the control range is actually +/- 1 degree. Hence my comment that it should be 2 or 3 degrees to bring the flow temp modulation in sooner.

                          However, one must always consider warm up times as Richard said.

                          The good thing about Intergas is that you can limit the maximum set point to force condensing all the time (hence my system is sized for 55 at - 3 iirc). Other "premium" brands have not allowed this.

                          However, returning to the override point. Evohome should be left to its own devices and optimisation routines.
                          Kind Regards - Dan Robinson (Jennings Heating Ltd)

                          Comment

                          • Dan_Robinson
                            Automated Home Ninja
                            • Jun 2012
                            • 347

                            Sorry... For some reason when I go to edit a typo in a post, I'm deleting them.
                            Kind Regards - Dan Robinson (Jennings Heating Ltd)

                            Comment

                            • The EVOHOME Shop
                              Site Sponsor
                              • Dec 2014
                              • 483

                              Originally posted by paulockenden View Post
                              So the proportional band is narrower with OT than it is with TPI?

                              That seems completely counter-intuitive to me.

                              But hey, if it works without producing hideous overshoots then great!

                              P.
                              It not called a proportional band either. Its a 'control bandwidth'...

                              I'll get my coat...

                              Comment

                              • bruce_miranda
                                Automated Home Legend
                                • Jul 2014
                                • 2307

                                Originally posted by The EVOHOME Shop View Post
                                Sadly Bruce I think you will find that they won't care. Intergas UK are not known for their controls knowledge! Why do you think I take these brands on as specialist businesses... I like a challenge!
                                This is probably the first time I have seen a company admit, in writing, to a problem that doesn't exist?

                                Comment

                                Working...
                                X