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Thread: Evohome firmware 02.00.19.31 Beta Trial - Exclusive for Automated Home Members

  1. #511
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    Quote Originally Posted by kevinsmart View Post
    With older firmware, and OpenTherm, the boiler still used to fire if the aggregated demand was much less than 10%.

    With the newer firmware it only seems to send a flow temperature above 10C to fire the boiler if the demand is at least 10%.
    Oh, that's disapointing to hear.

    One of the things that attracted me to OpenTherm if I ever ended up with a new boiler is I hate the 10% minimum heat demand threshold the Evohome system has when using a boiler relay.

    It leads to significant temperature cycling under low loads such as one or two bedroom radiators on at night. The room has to fall significantly below the set point before a 10% heat demand is reached, that then leads to an overshoot, then another undershoot etc...

    I've always said that the minimum ontime TPI algorithm in the Evohome is wrong - yes there should be a minimum ontime for the boiler of say 1 minute, as its not good or efficient to short cycle boilers, however the mistake is in not sending any heat demand at all until there is a demand of 10% - that can be a significant dip below set points in low heat conditions, (and especially with the new load scaling algorithm) enough to trigger oscillations as the control algorithm in the HR92's are opening their valves progressively and wondering why nothing happens for such a long time...

    Currently it works like this with a relay:

    Heat Demand - Relay on time percentage:

    0% - 0%
    1% to 9% - 0%
    10% - 10%
    11% - 11%

    etc. Everything below 10% is ignored. Here's how it should work:

    0% - 0%
    1% to 9% - 10%
    10% - 10%
    11% - 11%

    This way minimum ontime for the boiler is respected but even a small heat demand is enough to trigger the boiler and avoid cycling of temperatures and overshoots in low head demand conditions.
    Last edited by DBMandrake; 20th September 2020 at 12:46 PM.

  2. #512
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    Quote Originally Posted by kevinsmart View Post
    With older firmware, and OpenTherm, the boiler still used to fire if the aggregated demand was much less than 10%.

    With the newer firmware it only seems to send a flow temperature above 10C to fire the boiler if the demand is at least 10%.

    So I now have HR92s and HM80 UFH open even though the boiler is not heating.

    I guess it is energy saving but it does mean zones within 0.5C of set point may not heat.
    Even if I override the temperature to something ridiculous like 30C, the controller still reports no heat demand from that zone, thus no demand to the controller. I've tried overriding all the UFH zones and the only one that still wants to demand heat is the Hallway, using the evotuch sensor.

    Since the thermostats are bound to the evotouch, then the evotouch is bound to the HCC80R, the HCC80R seems to recognise the demand, there must be something not working correctly in software on the evotouch. I've tried disabling all the warm weather saving and optimisation features, but still to no avail.

    Anyone else had issues with opentherm boiler demand in conjuction with UFH? Heating season is coming up so I may revert back to standard firmware if a reset doesn't fix it, as I imagine the final release is still a while off.

    On a side note, is there any news on the app side of things? Or will that be released along with the final stable firmware?

  3. #513
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    Quote Originally Posted by DBMandrake View Post
    Oh, that's disapointing to hear.

    One of the things that attracted me to OpenTherm if I ever ended up with a new boiler is I hate the 10% minimum heat demand threshold the Evohome system has when using a boiler relay.

    It leads to significant temperature cycling under low loads such as one or two bedroom radiators on at night. The room has to fall significantly below the set point before a 10% heat demand is reached, that then leads to an overshoot, then another undershoot etc...

    I've always said that the minimum ontime TPI algorithm in the Evohome is wrong - yes there should be a minimum ontime for the boiler of say 1 minute, as its not good or efficient to short cycle boilers, however the mistake is in not sending any heat demand at all until there is a demand of 10% - that can be a significant dip below set points in low heat conditions, (and especially with the new load scaling algorithm) enough to trigger oscillations as the control algorithm in the HR92's are opening their valves progressively and wondering why nothing happens for such a long time...

    Currently it works like this with a relay:

    Heat Demand - Relay on time percentage:

    0% - 0%
    1% to 9% - 0%
    10% - 10%
    11% - 11%

    etc. Everything below 10% is ignored. Here's how it should work:

    0% - 0%
    1% to 9% - 10%
    10% - 10%
    11% - 11%

    This way minimum ontime for the boiler is respected but even a small heat demand is enough to trigger the boiler and avoid cycling of temperatures and overshoots in low head demand conditions.
    Hmm, this is interesting to know, so in reality I haven't got as much benefit to having OpenTherm as the boiler demand anymore apart from it telling the boiler what it wants the flow temperature to be (very useful for the UFH). Often at night in the winter we boost one or two radiators for a short period of time to knock the temperaure up by a degree or two, and the system absolutely excelled at that, with minimum overshoot. I have setup the pump over-run to be a bit longer on our boiler in order to prevent any damage from any possible short cycling since we use an automatic bypass.

  4. #514
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    Quote Originally Posted by ssb_tv View Post
    Even if I override the temperature to something ridiculous like 30C, the controller still reports no heat demand from that zone, thus no demand to the controller. I've tried overriding all the UFH zones and the only one that still wants to demand heat is the Hallway, using the evotuch sensor.

    Since the thermostats are bound to the evotouch, then the evotouch is bound to the HCC80R, the HCC80R seems to recognise the demand, there must be something not working correctly in software on the evotouch. I've tried disabling all the warm weather saving and optimisation features, but still to no avail.

    Anyone else had issues with opentherm boiler demand in conjuction with UFH? Heating season is coming up so I may revert back to standard firmware if a reset doesn't fix it, as I imagine the final release is still a while off.

    On a side note, is there any news on the app side of things? Or will that be released along with the final stable firmware?
    Thatís really bad and unfortunate for me too, because Iím planning to move to a house which has UFH and an OpenTherm boiler and I intend to install EvoHome again.

    I think https://www.automatedhome.co.uk/vbul...?31092-ally153 needs to investigate, if you provide your MAC address.

  5. #515
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    Quote Originally Posted by kevinsmart View Post
    That’s really bad and unfortunate for me too, because I’m planning to move to a house which has UFH and an OpenTherm boiler and I intend to install EvoHome again.

    I think https://www.automatedhome.co.uk/vbul...?31092-ally153 needs to investigate, if you provide your MAC address.
    Thanks, I'll drop him/her a PM, but I have a feeling resetting the evotouch should be the first port of call, it's just with 19 devices to rebind I'll have to find the time to get the system running from scratch again.

    UFH and OpenTherm worked perfectly on the stable build and 19.31, so something has changed I assume, or something has not carried over correctly when it upgraded itself to 19.33.

  6. #516
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    I have a strange issue, not sure if it's related to the beta. In my kitchen, one of two radiators keeps going to override. I'll notice it and cancel the override and it's fine but later on it's done it again.

  7. #517
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    Quote Originally Posted by Scubajoe View Post
    I have a strange issue, not sure if it's related to the beta. In my kitchen, one of two radiators keeps going to override. I'll notice it and cancel the override and it's fine but later on it's done it again.
    What temperature does it override to ? The previous set point for the schedule ?

  8. #518
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    Quote Originally Posted by DBMandrake View Post
    What temperature does it override to ? The previous set point for the schedule ?
    It actually just shows the override symbol on the controller and the app. It doesn't change the temperature.

    Thanks.

    20200921_094316.jpg

  9. #519
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    Quote Originally Posted by Scubajoe View Post
    It actually just shows the override symbol on the controller and the app. It doesn't change the temperature.

    Thanks.

    20200921_094316.jpg
    If it's only happening in one or two zones, choose a random time in the hour, remove all the batteries from the HR92's in the affected zone(s) and then refit them.

    This should fix it. Honest.

    If it does, it's a well known issue...not new in either of the Beta's - its been there ever since the update which introduced local override display on the controller, which I think was in late 2016 ???

  10. #520
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    Quote Originally Posted by DBMandrake View Post
    If it's only happening in one or two zones, choose a random time in the hour, remove all the batteries from the HR92's in the affected zone(s) and then refit them.

    This should fix it. Honest.

    If it does, it's a well known issue...not new in either of the Beta's - its been there ever since the update which introduced local override display on the controller, which I think was in late 2016 ???
    All seems fine now, thanks for your help.

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