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Thread: Is EvoHome controller a thermostat?

  1. #11
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    It's actually be kind of interesting (for a nerd like me) to read the evolution of the current system from whenever it first appeared

  2. #12
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    Quote Originally Posted by MrBoy View Post
    Anyway did this meant I did it right... Simply set the temperature sensor setting for my zone as Evotouch instead of remote? I tried this but saw no change in reported temp to confirm or deny I'd got it right.
    Yes, that's right. You should see the reported temp for the zone change on the Evotouch screen shortly after you change the setting (that is, within 30 seconds or so) - assuming the Evotouch controller is actually measuring a different temperature to the HR92, of course.

  3. #13
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    Quote Originally Posted by Ian_W View Post
    Something else to watch out for is that when the controller decides to charge its batteries, its measured temperature can increase by a few degrees C for several hours. This has caught me out when using the controller as the room's temperature sensor. Maybe there is a way to convince it to charge the batteries at a given time when this mis-reading won't be a problem, but I haven't found it yet.
    Funny, I graph all my zones and use the controller as the sensor for my hall zone (controller wall mounted) and I have never seen a noticeable temperature rise when the controller is charging its batteries on my graph, certainly not "a few degrees C for several hours". Maybe half a degree at most if that. I wonder what is different with your setup ?

    I do find I have to set the calibration to -1.0C to match an independent thermostat - but that offset required seems to be very constant and is probably due to overall heat production from the device independent of any battery charging.
    Last edited by DBMandrake; 16th January 2018 at 12:38 PM.

  4. #14
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    Quote Originally Posted by DBMandrake View Post
    Funny, I graph all my zones and use the controller as the sensor for my hall zone (controller wall mounted) and I have never seen a noticeable temperature rise when the controller is charging its batteries on my graph, certainly not "a few degrees C for several hours". Maybe half a degree at most if that. I wonder what is different with your setup ?
    Bearing in mind I installed my system only about three weeks ago and I've seen this behaviour once, it's possibly a one-off and perhaps I shouldn't have generalised so quickly. However I did see the reported temp go up by 2 - 3 C correlating with the battery charge indicator showing on the top right-hand corner of the controller display, and this took at least overnight to sort itself out. My set-up differs from yours insofar as the controller is on the shelf mount/cradle, but very rarely leaves it.

    ETA: there's an earlier reference to this behaviour in this post by @paulockenden.

    Quote Originally Posted by DBMandrake View Post
    I do find I have to set the calibration to -1.0C to match an independent thermostat - but that offset required seems to be very constant and is probably due to overall heat production from the device independent of any battery charging.
    Mine seems to be spot on, zero offset in steady state, compared to a known-good thermometer - provided I leave it alone and don't handle it. It seems very sensitive to hand heat, or perhaps I'm just holding it wrong (to quote a phrase...).
    Last edited by Ian_W; 16th January 2018 at 01:59 PM.

  5. #15
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    Quote Originally Posted by Ian_W View Post
    My set-up differs from yours insofar as the controller is on the shelf mount/cradle, but very rarely leaves it.
    In my experience, any handling of the controller will cause an issue when the controller is operating in a temperature sensing mode. Most people tend to hold the controller in their left hand which blocks the vents on the side.

  6. #16
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    In this configuration (during setup) why does it ask you to press the bind button?

  7. #17
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    Quote Originally Posted by Ian_W View Post
    Something else to watch out for is that when the controller decides to charge its batteries, its measured temperature can increase by a few degrees C for several hours. This has caught me out when using the controller as the room's temperature sensor. Maybe there is a way to convince it to charge the batteries at a given time when this mis-reading won't be a problem, but I haven't found it yet.
    This happened again in my system starting late yesterday evening. As of this morning the Evohome controller is still showing the battery charge indicator and is measuring about 2C higher than another thermometer in the same location (within a couple of inches). Normally Evohome agrees with this thermometer to within 0.5C, taking account of the rounding and bias towards the setpoint.

    The Evohome controller has been sitting in its cradle for a long time - probably several weeks. If I take the controller out of the cradle now, the battery shows full, and after several minutes the measured temperature drops. If I then put it back in the cradle, all is well for some tens of minutes but then the indicated temperature starts increasing again and levels out at about 2C higher than actual temperature. Incidentally the actual room temperature is now about 2C higher than the setpoint, as the room is no longer supposed to being heated.

    Last time this happened, I lost patience and had to re-boot the controller to get it out of this state. I don't know how long it's going to try to charge what appears to be an already fully-charged battery, and am not inclined just to wait and see when it sorts itself out which might result in the room not being heated properly later today when it needs to be.

    Does anyone else see this behaviour, and/or can anyone suggest tips to avoid it, please? For example, if it could be pre-empted by manually cycling the batteries every so often that would be inconvenient, but at least better than what's happening now.

  8. #18
    Automated Home Legend paulockenden's Avatar
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    I've not measured it scientifically, but in the room where I use the controller as a thermostat if it feels a bit chillier than it should I usually find the controller feels warm.

    P.

  9. #19
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    Quote Originally Posted by paulockenden View Post
    I've not measured it scientifically, but in the room where I use the controller as a thermostat if it feels a bit chillier than it should I usually find the controller feels warm.
    I seem to have the opposite problem - my controller won't charge the batteries until they are nearly flat!

    It gets left on the wall mount all the time and I never see a charging icon. A few days ago when I was measuring the proportional band for another thread I took the controller off the wall so I could have it beside me in the rooms I was testing, and immediately the battery symbol was at half - this is not uncommon as it doesn't seem to recharge the batteries until they get quite low.

    However I only had it off the stand for about 10 minutes before the big red "battery low, place place the unit back on the charger" warning appeared - the one that blocks you using the user interface altogether. Hrmph. Normally it will run for about 3 hours off the charger before this warning appears, not 10 minutes...

    So back it went on the charger. Either the batteries are faulty or the charging bug that lets the battery run nearly right down before recharging them (first reported nearly 2 years ago ?) is still there in the latest firmware...

    I've had the unit long enough now (2 1/2 years ?) that it may be time to try replacing the NiMH batteries - and with some better, slightly higher capacity ones! Maybe the batteries are getting a bit iffy.
    Last edited by DBMandrake; 2nd February 2018 at 10:45 AM.

  10. #20
    Automated Home Legend paulockenden's Avatar
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    There's something really odd about the temp reported by the controller. If you graph it it's very bumpy, unlike the temps from an HR92 or wall stat which tend to be nice and smooth.

    I don't mean oscillations, I mean a sawtooth like appearance.
    chart (6).jpg
    P.

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