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Thread: Evohome is Noisy - please help me

  1. #171
    Automated Home Legend paulockenden's Avatar
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    Optimisation works well for me, all apart from one room.

    It's annoying that I can no longer just disable it for that zone. Taking away useful functionality always leads to complaints!

  2. #172
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    Optimum start and off has been working for me great so far as well. I have it set to come on a maximum of 1 hour before. I only turned Optimum off on a few months ago but Iíve found this feature working well so far.

  3. #173
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    Quote Originally Posted by mtmcgavock View Post
    Optimum start and off has been working for me great so far as well. I have it set to come on a maximum of 1 hour before. I only turned Optimum off on a few months ago but I’ve found this feature working well so far.
    I had some issues with optimal start seemingly not learning properly when I first got Evohome (nearly 2 years ago now) with the main problem being that it would come on as much as an hour too early to meet the target in some rooms and seemingly never learn to come on later. Because of that I had the maximum lead time limited to 2 hours as a workaround.

    I don't know what changed - whether it has been the two (count them! ) intervening firmware updates over those two years, whether its because I changed to DTS92 wall stats in some of the problematic rooms, (like the living room - whose optimal start is now spot on) or what has changed, but when I checked recently every single zone was hitting its target on the money with most at the set point about 15 minutes before the target if not right on the target. I now trust it so much that I have the maximum lead time set back to the default of 3 hours, but I have never seen it attempt to use more than two hours...

  4. #174
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    Perhaps I better try it again! It may be recent upgrades have sorted the issue that it seems I was not alone with.

  5. #175
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    Quote Originally Posted by G4RHL View Post
    Perhaps I better try it again! It may be recent upgrades have sorted the issue that it seems I was not alone with.
    I think part of the issue may be that it has limits to how far it is wiling to "learn", and some room/radiator combinations may exceed those limits.

    What I mean by that is it is taking two factors into account when calculating optimal start lead time:

    1) Temperature differential between the current temperature and the next target, eg how many degrees does the room need to increase to reach the target. No learning is needed here as it just subtracts the target from current temperature.

    2) At what rate in degrees per hour can the room heat up when commanded - not quite a simple linear relationship, more of a flattening out curve since as the room temperature increases the differential to the radiator panels reduces (less heat output) and the differential to the outside temperature increases (more heat loss) so this results in a curve not a straight line.

    The learning process has to learn at what rate the room heats up so that combined with the differential it can calculate a start time. What I suspect the problem could have been is the learning algorithm may only adapt so far - lets say a maximum of 5 degrees per hour and a minimum of 1 degrees per hour. If your room heats faster than 5 degrees per hour it will always come on too early and will never fully adapt, if your room heats slower than 1 degree per hour it will never come on soon enough, but if your room is somewhere in between it will adapt correctly.

    When I had problems I noticed that the two rooms that gave me the most trouble had exactly these extreme characteristics - the living room - as measured at the HR92, heated up very quickly (over 6 degrees per hour) and consequently always came on too early, as much as an hour, while the hallway (about 0.5 degrees per hour in winter, temperature measured at the controller on the wall) was actually always late and didn't hit its target until as much as an hour late, although to be fair it often struggled to hit the target at all. Neither room ever learnt its start up time properly.

    Since that time the Living room has changed to a DTS92 on the far side of the room near the door and it also has a baby cot in front of the radiator slowing the warm up rate of the room. Optimal start seems nearly perfect in the Living room now. Part of this may be that a suitably placed DTS92 measures the real (slower) warm up rate of the room, while an HR92 thinks the room is warmed up and starts throttling back long before it actually is due to it measuring the warm side of the room beside the radiator...

    The hallway seems OK for optimal start at the moment but I suspect in the depths of winter when it is struggling to make the set point it will be late again. But I don't mind late as much as I mind a radiator coming on an hour or more earlier than it needs to be.

    Is it possible that your rooms that were coming on too early have very fast warm up times, at least where the temperature is measured ? And do you use HR92's or wall stats in those rooms as the zone sensor ?
    Last edited by DBMandrake; 9th November 2017 at 10:13 AM.

  6. #176
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    I'm not sure I really understand the point of optimisation. I'm quite happy to decide when the heating should come on in various rooms. In fact there's only two or three where we have regular schedules and all the rest should really stay at background unless we want to use them. An occupancy detector would be useful - or even just a button to press when you go in and press again when you have finished.

  7. #177
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    Quote Originally Posted by filbert View Post
    I'm not sure I really understand the point of optimisation. I'm quite happy to decide when the heating should come on in various rooms. In fact there's only two or three where we have regular schedules and all the rest should really stay at background unless we want to use them. An occupancy detector would be useful - or even just a button to press when you go in and press again when you have finished.
    You may be over thinking it. If you say turn a zone Ďoní at 7am then on a warm morning it might hit your target temperature by 7.40. On a really cold morning, the set temperature might not be reached until 8.30. If you want 20C in, say, 3 zones at 7.30, then why not let Evohome do all the thinking? That said, many of us would like Honeywell to go back to individual zone optimisation rather than the all ON/OFF that we have now.

  8. #178
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    Quote Originally Posted by filbert View Post
    I'm not sure I really understand the point of optimisation. I'm quite happy to decide when the heating should come on in various rooms. In fact there's only two or three where we have regular schedules and all the rest should really stay at background unless we want to use them. An occupancy detector would be useful - or even just a button to press when you go in and press again when you have finished.
    The point of optimal start is you specify in your schedules when you want the room to be at the scheduled temperature, not when you want the radiator to come on to start heating towards the set temperature.

    This means that as the seasons change and the warm up times of the rooms get longer (winter) or shorter (summer) the system will automatically adjust the lead time for each zone to hit the target at the specified time without coming on any earlier than necessary. This means you don't need to reprogram your schedules as the seasons change or if you get an unexpected cold snap.

    So in summer a zone might only take 20 minutes to reach the target but in the depths of winter it might take 90 minutes, and Evohome will figure this out for you and constantly adapt as conditions change.

    If your bathroom is set to reach 22 degrees at 6:30am every morning for showers it will do that regardless of whether it needs to run for 20 minutes or 2 hours ahead of time to achieve this. (You can set a maximum lead time that it is allowed to use though - which defaults to 3 hours)

  9. #179
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    You could try putting up some sound proof foam perhaps to deaden the noise a little bit. It won't make it totally silent, but might take the edge off if it bothers you that much.

  10. #180
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    Quote Originally Posted by Funder1 View Post
    You could try putting up some sound proof foam perhaps to deaden the noise a little bit. It won't make it totally silent, but might take the edge off if it bothers you that much.
    Sometimes just putting a small piece of wood, pressed against the side of the metal part of the valve with the other end touching the wall may be suffice to stop any resonating. Does not always work but worth a try if the sounds bothers you.

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