Why your smart thermostat might run before its programmed times

On a recent Internet of Things Podcast episode, we took a question from our Voicemail hotline about smart thermostats. This question was specific to the ecobee thermostats, although it could apply to other brands as well. Essentially, the question is why the smart thermostat doesn’t always run at programmed times, instead turning the HVAC on an hour or even 90 minutes sooner than expected.

It’s a great question and one I hadn’t considered because I haven’t noticed my own ecobee behaving this way. After learning the reason, however, I looked for this situation to occur and sure enough, it has.

In the case of the ecobee, this is due to a feature called Smart Recovery. Technically, Smart Recovery is used in tandem with the learning aspects of the thermostat. Over time, smart thermostats can learn not just your personal routines but also how long it takes your HVAC system to arrive at a requested or programmed temperature.

I have an older HVAC system, for example, so it may take an hour to warm up the house on a brisk morning. You may have a more efficient system and better insulation or higher quality windows in your home. (I’m guessing you probably do since we’re about to replace our HVAC and windows, which were all installed two decades ago). So in your more efficient home, it may only take 20 minutes to raise the morning temperature to the desired number. That’s where Smart Recovery comes in.

According to the ecobee support site, here’s how it works:

Smart Recovery preemptively heats or cools your home in anticipation of a transition in your schedule. The higher the difference in set points between these two programmed Comfort Settings, the earlier the system may engage, and the longer the system may run to reach the target set point.

For example, let’s say your set point during your scheduled Away period is 78 degrees, while during your scheduled Home period, it’s set to 72. Using the gathered data, the ecobee will turn on your air conditioner before your schedule shifts from Away to Home so that by the time your Home period comes into effect, the temperature will already be at 72 degrees (as opposed to waiting until the schedule changes and then trying to bring the temperature down from 78 to 72).

Again, I wasn’t aware of this although I later found out that I had the Smart Recovery feature enabled. And that’s worth a mention too. You can disable Smart Recovery but not from the ecobee app.

Instead, you can access this setting by signing in to the ecobee website and navigating to Settings then Preferences. There you’ll see Smart Recovery options for both heating and cooling. Alternatively, you can change the setting directly on your ecobee thermostat, again from Settings, then Preferences.

Every smart thermostat uses different algorithms and approaches to maximize comfort while minimizing energy use. Even if you don’t have an ecobee, for example, your thermostat may have a similar function with a different name. So if your HVAC system seems to turn itself on sooner than you’d expect, you may want to look in the settings to see exactly what’s causing that. Personally, I like how Smart Recovery works and I’ll like it, even more, when we replace our HVAC and windows. I’m leaving it on for now.

To hear this question in full, as well as our discussion on the topic, tune in to the Internet of Things Podcast below: