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

  1. #101
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    It does modulate as I see a high flow temp when it first comes on, the issue at moment is it’s not modulating low enough and causes it to cycle off or overshoot.

  2. #102
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    Quote Originally Posted by blowlamp View Post
    Do you think Ideal might be referring to the way Honeywell OpenTherm devices operate at full burner output until they are within a degree or two of set temperature, at which point they then start to request a specific control flow temperature?
    That is not the way that the ATag appears to respond. With both CH and HW, the boiler TSet Calculated (flow) temperature rises slowly towards the TSet Max set in the boiler profile. Looking at the boiler manual, the temperature difference between flow and return guides the speed/gradient of the boiler temperature ramp up.

    Once the TSet Calculated equals TSet Max, it stays there until all the zones are within a 2C range of their target temperatures. The boiler TSet Calculated temperature then reduces. For most of this afternoon, with all 12 zones at their target temperature, the boiler has operated in a flow/return range of 52 to 55C/ 40 to 45C. The only time that TSet Calculated rose was when my wife increased a zone temperature by 2C. It fell back within 10 to 15 minutes.

    No short cycling here when TSet Calculated was close to TMax Set. I appreciate that we are not talking like for like here. Different boilers and different controls - albeit, both Opentherm.

  3. #103
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    The OpenTherm controller won't be able to affect the ramp rate of the burner.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  4. #104
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    Quote Originally Posted by Dan_Robinson View Post
    The OpenTherm controller won't be able to affect the ramp rate of the burner.
    Yeah I thought as much also, surely the boiler software is solely responsible for that.

    My thoughts are that they have messed the boiler pcb up and are sorting it but not taking all the blame.

  5. #105
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    Precisely.

    Boiler logic varies, and the ignition rate is also different and can affect micro loads if the burner is chucking out 7kW into a rad that can only take 500w.

    Some boilers have return sensors, others do not. There are also all sorts of different heat exchanges, burners, fans etc.

    As such there is no way a universal controller would/should have direct control over the gas side of the boiler. It can/should only have influence over the flow temperature. The better boilers too will have their own ability to limit flow temp - Intergas being one, Vaillant another, where Tmax can be limited in the boiler software.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  6. #106
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    Quote Originally Posted by Dan_Robinson View Post
    Precisely.

    Boiler logic varies, and the ignition rate is also different and can affect micro loads if the burner is chucking out 7kW into a rad that can only take 500w.

    Some boilers have return sensors, others do not. There are also all sorts of different heat exchanges, burners, fans etc.

    As such there is no way a universal controller would/should have direct control over the gas side of the boiler. It can/should only have influence over the flow temperature. The better boilers too will have their own ability to limit floor w temp - Intergas being one, Vaillant another, where Tmax can be limited in the boiler software.
    Mine is limited to max 55c flow temp thinking this would change the heating curve it still sits at 48c most of time even though how is upto temp and it’s cycling on and off and there’s an 8c diff between flow and return.

  7. #107
    Automated Home Ninja Dan_Robinson's Avatar
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    If it is any consolation, the savings a year from modulating much further down from 55 will be less than an afternoon down the pub.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  8. #108
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    Quote Originally Posted by richardc1983 View Post
    It does modulate as I see a high flow temp when it first comes on, the issue at moment is it’s not modulating low enough and causes it to cycle off or overshoot.
    When you say “low enough”, is it getting to the lowest power it can? If so, there’s nothing more that can be done. If your boiler has a low power output of, say, 6kWh, and it’s a 5kWh day, it’s going to have to cycle.

  9. #109
    Automated Home Ninja Dan_Robinson's Avatar
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    Quote Originally Posted by dty View Post
    When you say “low enough”, is it getting to the lowest power it can? If so, there’s nothing more that can be done. If your boiler has a low power output of, say, 6kWh, and it’s a 5kWh day, it’s going to have to cycle.
    What is a 5kWh day?
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  10. #110
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    Quote Originally Posted by Dan_Robinson View Post
    What is a 5kWh day?
    A day where the outside temperature means your heating system needs to provide 5kwh to maintain the set temperature.

    My boiler tends to cycle in warmer weather, but since its been cold its bang on stays on at around 32c flow temperature.

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