Opentherm with Evohome

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  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2309

    #31
    Would be keen to know what the Intergas issue is. Who in the world would invest in Evohome and run a single zone!

    Comment

    • top brake
      Automated Home Legend
      • Feb 2015
      • 837

      #32
      Originally posted by HenGus View Post
      I have at last found an ecotechnician that is keen to work with me to provide an Opentherm solution with an Atag boiler. That said, I am struggling with a couple of things which are the costs/benefits of a £250 additional cost for an EBus to Opentherm converter and Opentherm bridge, and getting confirmation that the Atag Opentherm connection can cope with multiple HR92 zones? FWiW, I finally got confirmation from the guys at Intergas that their boilers do have an issue which is under investigation in The Netherlands.
      ATAG is OT so no adapter needed, just wire OpenTherm Bridge
      ATAG supports multizoning with evohome

      thanks
      I work for Resideo, posts are personal and my own views.

      Comment

      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        #33
        Originally posted by HenGus View Post
        and getting confirmation that the Atag Opentherm connection can cope with multiple HR92 zones?
        I can't see how the number of HR92 zones could be an issue - the boiler is not aware of how many zones there are.

        The heat demand of the different zones is aggregated by the Evotouch controller and one flow temperature is chosen (at a given moment in time) to meet the demand and sent via OpenTherm to the boiler. Whether this is one HR92 zone or 10 is irrelevant to this process.

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        • paulockenden
          Automated Home Legend
          • Apr 2015
          • 1719

          #34
          Perhaps someone mentioned the "Single Zone Thermostat", and things got confused?

          P.

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          • HenGus
            Automated Home Legend
            • May 2014
            • 1001

            #35
            Originally posted by top brake View Post
            ATAG is OT so no adapter needed, just wire OpenTherm Bridge
            ATAG supports multizoning with evohome

            thanks
            Atag Technical Support would beg to disagree:

            Quote: With the Honeywell Evohome system there needs to be a Honeywell OpenTherm bridge that connects to our OpenTherm blue bus connection. That is the only controls connection to the boiler. A blue bus connector needs to be ordered from us by your Atag installer, part number S4745000 for an external third party control to connect with our boiler. Unquote

            edit:

            Both TopBrake and Atag are correct (apologies TB). It would appear that Evohome O/T Bridge does connect to what Atag calls a Blue Bus but it requires a simple connector/ adapter.
            Last edited by HenGus; 28 October 2016, 09:06 PM. Reason: Add to info

            Comment

            • HenGus
              Automated Home Legend
              • May 2014
              • 1001

              #36
              Originally posted by DBMandrake View Post
              I can't see how the number of HR92 zones could be an issue - the boiler is not aware of how many zones there are.

              The heat demand of the different zones is aggregated by the Evotouch controller and one flow temperature is chosen (at a given moment in time) to meet the demand and sent via OpenTherm to the boiler. Whether this is one HR92 zone or 10 is irrelevant to this process.
              This was the response that I got from an eco technician/installer (well known to TB - I suspect):

              The problem is that the boiler or Evohome (no one really knows which at the moment) doesn't cope with modulating the setpoint with multiple zones.

              My theory is that there is too much data and the boiler PCB can't interact quickly enough with the OpenTherm bridge so it drops its knickers and runs at whatever the maximum setting is.


              Read more: http://www.diynot.com/diy/threads/in...#ixzz4ONroCcTm

              The problem is also reported on The Evohome Shop Forum. Intergas Technical Support confirmed to me over the phone that there is a known issue with the handling of multiple zones and they had no idea when a fix would be rolled out; however, they acknowledged (as they have had a visit I suspect from TB) that the Honeywell O/T Bridge will connect to their boilers.

              Comment

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