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

  1. #81
    Automated Home Ninja Dan_Robinson's Avatar
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    Sounds like flannel to me.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  2. #82
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    Having spent more time than I should looking at my boiler (Atag with OT) maximum flow temperature is limited by the TMax temperature set in the boiler profile. HW and CH will control to the the TMax temperature and, as far as CH is concerned, the manual set temperature is ignored.

    For example, this morning I checked the boiler when it was in the last stages of re-heating my cylinder and the calculated TMax Set was 70C with a profile TMax of 70C. When CH came on with 4 zones below the target temperature, the boiler flow temperature slowly climbed to calculated TMax of 70C and then dropped down quickly to a calculated TMax of 52 with a return flow of 42. Interestingly, when there is no heat demand, the calculated TMax falls to 20C.

    I appreciate that a lot of the above may be boiler specific.

  3. #83
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    Quote Originally Posted by Dan_Robinson View Post
    Sounds like flannel to me.
    I agree...

  4. #84
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    Ive replied with this;

    So are you saying the new pcbs are going to inhibit this ability for the Honeywell controller to control burner output or is it going to be a case of fully allowing the Honeywell control of the boiler so as not to cause a conflict with the two fighting each other?

  5. #85
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    So what do you think the actual issue is then? That they have found issues in their pcb and are trying to correct it and blame Honeywell in the process.

  6. #86
    Automated Home Ninja Dan_Robinson's Avatar
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    Well, although I am working from an old spec for Opentherm, I can't see anything that says the OT master has any direct say over what the burner does. That would be potentially dangerous, even if Honeywell designed the combustion train too.

    The fact remains, this is a master-slave relationship and the boiler will do what its told through Tmax. If ti doesn't understand then it will default to full power to ensure comfort.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  7. #87
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    Quote Originally Posted by Dan_Robinson View Post
    Well, although I am working from an old spec for Opentherm, I can't see anything that says the OT master has any direct say over what the burner does. That would be potentially dangerous, even if Honeywell designed the combustion train too.

    The fact remains, this is a master-slave relationship and the boiler will do what its told through Tmax. If ti doesn't understand then it will default to full power to ensure comfort.
    So from what they have said the boiler doesn’t understand what is being asked of it so just doing as it wants to achieve comfort.

  8. #88
    Automated Home Ninja Dan_Robinson's Avatar
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    That's my guess.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  9. #89
    Automated Home Legend paulockenden's Avatar
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    Quote Originally Posted by richardc1983 View Post
    it is apparent that Honeywell opentherm devices control both the flow temperature and the burner output, whereas most only operate the boilers flow temperature.
    Aren't the two things pretty much equivalent?

    Reduce the burner output and it'll reduce the flow temperature.

    P.

  10. #90
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    Quote Originally Posted by paulockenden View Post
    Aren't the two things pretty much equivalent?

    Reduce the burner output and it'll reduce the flow temperature.
    Not really.

    If you specify a target flow temperature using OpenTherm the boiler will modulate the burner kW output as necessary to meet and maintain that requested flow temperature.

    If you were to specify a target burner output in kW directly using OpenTherm (which I don't think it can do anyway) the flow temperature that you ended up with would be all over the place depending on the load presented by the radiators, so wouldn't provide any useful control.

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