Adaptive Recovery

[stestardi]

Would love to see your thermostats do adaptive intelligent recovery. In other words, if I set a program for 70F at 6:00AM, instead of the heat coming on at 6:00AM, have the thermostat start the heat early enough in advance to ensure my home is at 70F at 6:00AM.

Thanks.

Steve

[Lbendlin]

I am collecting all the data from my thermostats in a little database. I plan to learn the hysteresis of the house, taking outside temperature into account, and then to apply this to adjust the schedule myself. Personally I wouldn't want a third party make these decisions for me.

[stestardi]

I am collecting all the data from my thermostats in a little database. I plan to learn the hysteresis of the house, taking outside temperature into account, and then to apply this to adjust the schedule myself. Personally I wouldn't want a third party make these decisions for me.

That may work in a climate with fairly constant temperatures, but it won't work in climates where the temperature varies substantially day to day, especially if you have a large setback at night (ours is 55F). On warm nights, it takes only 30 minutes or so to get our house up to temperature. On cold nights, it takes a couple of hours.

Our current thermostat (a 20 year old Honeyell) characterized our house and HVAC system in a few weeks, and now gets our house to the target temperature within minutes of the prescribed time, saving lots of energy (or conversly, lots of complaints that it's too cold) vs. me manually setting the recovery time. And the feature is selectable, as it should be when RTCoA implements it.

[Lbendlin]

Good points. I also applied for a Wunderground API key. That way I can use the local forecast together with the history data to judge how long the recovery is likely going to be. Did your old Honeywell have an external temperature sensor?

[stestardi]

Oh, and my Honeywell does not have an outdoor sensor, but it seems to do pretty well regardless.

[fecund]

Yes, I am working on something like this right now. In an overview you could something like:

Look back historically at when the hvac is on and what degree it started at and when it ended. You could then extrapolate this into a "degree/time" value. Then you can weight that value against the outside temperature. Then just do the math and push your setpoint back in time based on the result.