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

  1. #481
    Automated Home Legend paulockenden's Avatar
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    Well... yes and no. Weather apps seem to manage OK, and they poll directly.

  2. #482
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    Quote Originally Posted by paulockenden View Post
    Well... yes and no. Weather apps seem to manage OK, and they poll directly.
    Different setup there, vs. paying for access to data via a secured and rated API data provider.

  3. #483
    Automated Home Legend paulockenden's Avatar
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    But there's no need for it to be different. My point is that the controller can use the same setup as the millions of apps out there.

  4. #484
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    Slightly different problem here. For the last few days, every time Iíve looked at the Evotouch, itís said the outside temp is 13C. Having just out of the car, where the temp was reading 17C, it was the same. I tried disconnecting and then reconnecting the WIFI but this has no effect. Next I took the batteries out and then put them back in. Interestingly, the date changed to 18 Aug at 2113. Iíve never noticed it do this before on restart, so I wonder whether this was when something in the firmware hung-up. Iíve not noticed any problems with the schedules. Once the WIFI connected again, the outside temp was restored at 16C. It doesnít affect me that much as itís on OpenTherm boiler (please implement the boiler sending the outside temperature to allow flow temp setting based on outside temp) but it was some strange behaviour to observe.

  5. #485
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    Quote Originally Posted by paulockenden View Post
    Not if the API pushed a URL and a grep string.
    That would only work for very simplistic single query/result API's which don't have seperate authentication processes or persistent login state, and would therefore not be very versatile or future proofed.

    Case in point - good luck trying to query the Honeywell API used by the iPhone app (and python evohomeclient/domoticz etc) using just a single get request with a grep parser..

    Quote Originally Posted by roydonaldson View Post
    If the API is being rate limited, it doesn't particularly matter whether it's the cloud or the end device that is doing the polling. If the rate is still above the committed rate limit, then the API will decline the request.
    Of course it matters. If Honeywell servers act as an intermediary they only have to poll each weather location from the weather service once per update cycle regardless of how many Evohome owners live in that area. Effectively they are acting as a reverse proxy.

    So one query to the weather service every X minutes for weather for "London" vs hundreds of Evohome's in London individually querying the weather service using the same shared Honeywell API key... With a proxy you only need one query per location which has Evohome customers per polling cycle then Honeywell can do what they want between their servers and Evohome units.

  6. #486
    Automated Home Legend paulockenden's Avatar
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    If the MITM weather API is using “London” as the granularity then I can understand some of the problems!

    Hopefully it’s using postcodes (perhaps minus last two digits). I wonder how many of those have multiple Evohome installs?

  7. #487
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    Quote Originally Posted by paulockenden View Post
    If the MITM weather API is using “London” as the granularity then I can understand some of the problems!

    Hopefully it’s using postcodes (perhaps minus last two digits). I wonder how many of those have multiple Evohome installs?
    Which online weather service gives weather reports more granular than by city ? None that I've seen.

    Also if you're in a smaller city/town you're likely to be getting a weather report for a nearby larger city anyway. For example I'm in Motherwell and while nearly all weather services list it as a distinct location, the report from nearly all of them is identical to Glasgow, which is 15 miles away and has it's own microclimate that frequently has different weather conditions.

    One of the few services which gives a distinct and accurate weather report for Motherwell is Meteogroup. (WeatherPro on the iPhone)

    The main issue I'm seeing with the Evohome temperature though is not inaccuracy, but lag. If you allow for 4 to 6 hours of lag its usually within about 2C of the true temperature which is close enough for the weather related features to work, however the 4-6 hour lag unfortunately makes it useless when it really matters - when the temperature is going up or down quickly in the morning and evening.

  8. #488
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    Re: Load Scaling
    I am still a little concerned that some of the new features are somewhat esoteric in behaviour and the guidance is not clear enough to fully understand any implications or in fact identify a potential logic flaw. On Saturday the weather was cool enough that I switched over from DBMandrake’s patent “summer setting” to normal and immediately 3 zones called for heat. 2 for 75% and 1 for 100%. The evohome boiler control relay showed 100%. The result? Nothing happened ☹ I left it for 10 mins with still nothing happening and then due to my wife’s unhappiness with the lack of heating, I went into load scaling, switched over from normal to partial, and the boiler relay switched and heat started being produced. I then switched load scaling back to normal and the boiler relay stayed on. So this raises a few questions
    1 – what is the requirement for Normal or Partial in load scaling. The guide says that normal is for a well insulated house. So what is regarded as well insulated. I live in an early 90’s timber frame house with 100mm wall insulation, cavity wall, 300mm loft insulation, heat recover ventilation system, 18mm double glazing, insulated floor. Is this “well insulated” or is it based on passivhaus specification and if so what value?
    2- what exactly does the Normal vs Partial setting do in terms of load scaling?
    3 – I believe there was a mention that load scaling algorithm is “self learning”. What is the time to “learn” and what does that mean to my daily running whilst it learns?
    4- I have a combi boiler but not opentherm. I tend to change the boiler temp over the season to regulate the flow temp to a degree and meet demand. With load scaling can I dispense with that and if so where should I set – full or half or other?
    I know it has been mentioned before by others but whilst these features should “help” they should not appear to “hinder”. If I want heat I need heat. An algorithm saying the opposite is not going to endear itself particularly to the non-techy in the house who don’t appreciate the sophistication and awesomeness of evohome algorithms and just want heat !!

  9. #489
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    Quote Originally Posted by SteveP View Post
    Re: Load Scaling
    I am still a little concerned that some of the new features are somewhat esoteric in behaviour and the guidance is not clear enough to fully understand any implications or in fact identify a potential logic flaw. On Saturday the weather was cool enough that I switched over from DBMandrake’s patent “summer setting” to normal and immediately 3 zones called for heat. 2 for 75% and 1 for 100%. The evohome boiler control relay showed 100%. The result? Nothing happened ☹ I left it for 10 mins with still nothing happening and then due to my wife’s unhappiness with the lack of heating, I went into load scaling, switched over from normal to partial, and the boiler relay switched and heat started being produced. I then switched load scaling back to normal and the boiler relay stayed on. So this raises a few questions
    That sounds to me like a momentary loss of comms between the Evotouch and the boiler relay. If it said 100% heat demand for the boiler relay and the relay stayed off, then that is not right, and is unrelated to load scaling.

    What probably happend is that toggling load scaling on then off changed the heat demand, (reducing it actually) and this would force the Evotouch to send a new heat demand to the relay, and this time the message got through.

    If you'd left it alone after 20 minutes the original heat demand would have been resent and the problem would have sorted itself. Heat demands are sent to the relays once every 20 minutes, (if it remains the same) and every time the heat demand changes.

    1 – what is the requirement for Normal or Partial in load scaling. The guide says that normal is for a well insulated house. So what is regarded as well insulated. I live in an early 90’s timber frame house with 100mm wall insulation, cavity wall, 300mm loft insulation, heat recover ventilation system, 18mm double glazing, insulated floor. Is this “well insulated” or is it based on passivhaus specification and if so what value?
    2- what exactly does the Normal vs Partial setting do in terms of load scaling?
    Yes, the normal and partial modes are a bit nebulous in their description in relation to insulation.

    What I can tell you is that partial provides less load scaling than normal. So for example if a zone which normally requires little heat asks for 100% heat demand "normal" might scale that down to 25% boiler demand, partial might scale it to 50% and off will leave it alone at 100%. Keep in mind that these figures are examples - load scaling automatically adapts in every zone so the amount it scales down the heat demand is specific to each zone and also varies over time as it learns the characteristics of the zone.

    All you really need to keep in mind is that load scaling scales down the heat demand by a ratio in a given zone, and that ratio is adapted over time as well. Also the heat demand sent to the boiler is partially additive among zones. So for example many zones asking for a low heat will generate more boiler heat demand than one zone asking for a low heat - not the case with load scaling off where the number of zones doesn't matter only the highest demand of all zones.

    When load scaling is off the boiler demand is always whatever the figure from the highest demanding individual zone is. So if one zone goes to 100% the boiler will go to 100%. This is not the case with load scaling where one zone going to 100% by itself will not force the boiler to 100%. This helps minimise overshoots and provide better temperature regulation, however it can slow the change in temperature a little.

    If load scaling is working you'll see the boiler demand will be lower than the highest demand from a particular zone - often dramatically so.
    3 – I believe there was a mention that load scaling algorithm is “self learning”. What is the time to “learn” and what does that mean to my daily running whilst it learns?
    I've been watching mine a bit during the beta period and I haven't been able to work out what the learning period is or how quickly it adapts. I suspect that it increases the scaling factor on zones which have a tendency to overshoot.
    4- I have a combi boiler but not opentherm. I tend to change the boiler temp over the season to regulate the flow temp to a degree and meet demand. With load scaling can I dispense with that and if so where should I set – full or half or other?
    I also used to vary my flow temperature with the seasons - up to 70 (and occasionally 75 if we got a really cold sub zero blast) and then down to about 60 in the summer, otherwise I'd get very uncomfortable overshoots in warm weather, especially when schedule changes occured.

    Since I started using load scaling in the first beta I've left the flow temperature alone at 70 and haven't needed to turn it down in summer and haven't suffered any significant overshoots.

    However in the second beta a feature was introduced that disables load scaling in zones where a large manual override is applied, so if you do make a large manual override that is 1.5C or more above the current temperature it will once again let the boiler go to 100% and may result in an overshoot in summer, however without this it could be impossible to get heat in a single zone - see the discussion about this earlier in the thread.

    So you might still see a little overshoot if you manually crank a zone up but if you just let the schedule do its thing load scaling should prevent major overshoots even when new zones are coming online and just generally do a better job at reaching and maintaining set points - it certainly does for me.
    I know it has been mentioned before by others but whilst these features should “help” they should not appear to “hinder”. If I want heat I need heat. An algorithm saying the opposite is not going to endear itself particularly to the non-techy in the house who don’t appreciate the sophistication and awesomeness of evohome algorithms and just want heat !!
    Which is exactly why the change was added in the second beta to let manual overrides override the load scaling as well so that when you want heat NOW (like turning up a bathroom radiator) you can get it now...

    So I think load scaling is working pretty well now - if you're unsure about it try it in partial mode first and see what you think over several days. Normal mode is quite a bit more aggressive at cutting down the heat demand than partial mode and I found it a bit too much for my house.
    Last edited by DBMandrake; 7th September 2020 at 09:39 PM.

  10. #490
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    Thanks DBMandrake, very helpful and clear explanation. Hopefully the issue with the lack of heat was a comms "blib" as I couldn't understand why the boiler relay was showing 100% and yet not engaging and yes the switching to partial mode would make sense that it did fire the relay as it resent the command. I'll have a bit more of a play and see what the partial vs normal mode does in terms of overshoot control and not having to keep adjusting the boiler output

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