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Thread: Adjusting Zone Temp when Optimum Stop is Enabled

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    Default Adjusting Zone Temp when Optimum Stop is Enabled

    A first for me. We have a visitor coming, so I decided to adjust the temperature profile for one of my zones. The Optimum Stop icon was enabled. After confirming the revised schedule, nothing happened. The revised schedule was showing on the controller but the zone was stuck in Optimum Stop. I guess that it would have stayed there until the next check point was reached. I cleared the problem by turning off Optimum Stop and turning it back on again.

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    I used optimum stop for a while, I always had to use override to defeat it, editing schedule would not. gave up on it in the end, e.g in the lounge, with a setpoint of 15 @ bedtime, we'd be sat for the last 45-60 mins watching telly thinking its a bit chilly in here now...or you end up constantly tweaking your schedule based on what you think optimum stop might do...and its also weather (= house heat loss rate) dependent... so it was too much like hard work. to be useable I think needs to be per-room, there are some zones where it makes sense and somewhere it doesn't. I am now back to optimum stop and start off for the winter.

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    I repeat, it was REALLY STUPID of Honeywell to remove the per zone optimisation feature in the latest evohome controllers. Bring it back will ya Honeywell.

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    Quote Originally Posted by sandyman View Post
    I used optimum stop for a while, I always had to use override to defeat it, editing schedule would not. gave up on it in the end, e.g in the lounge, with a setpoint of 15 @ bedtime, we'd be sat for the last 45-60 mins watching telly thinking its a bit chilly in here now...or you end up constantly tweaking your schedule based on what you think optimum stop might do...and its also weather (= house heat loss rate) dependent... so it was too much like hard work. to be useable I think needs to be per-room, there are some zones where it makes sense and somewhere it doesn't. I am now back to optimum stop and start off for the winter.
    Keep in mind that the objective of optimal stop is to have the temperature drop 0.5 degrees below the current set point at the time the next lower set point is scheduled.

    So for example, say you have 21 degrees scheduled from 6pm to 11pm then 5 degrees from 11pm onwards. Optimal stop will try to turn the radiator off (technically, drop to the following set point) as early as possible between 6pm and 11pm whilst keeping the temperature from falling below 20.5 degrees at 11pm. It's aiming to hit exactly 20.5 at 11pm.

    Half a degree doesn't sound like much and if the room was 20.5 the whole time with the radiator remaining warm it wouldn't feel cold, however we are more sensitive to changes in temperature than we are to the specific temperature, so this unexpected drop from 21 to 20.5 over a relatively short time, (with the radiator turned right off and getting cold) will feel "chilly" after being acclimatised to 21.

    I like Optimal Start and use it, I turned Optimal stop off LONG ago. Good on paper, poor in practice for multiple reasons. Better to just schedule your set point to drop a bit earlier.
    Last edited by DBMandrake; 12th December 2016 at 01:53 PM.

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