Thermostat settings for upstairs and downstairs during the summer...

Not sure why you'd have the downstairs set higher.

My kids are in college now so no one lives upstairs, so we don't even adjust it anymore. Upstairs stays on 77° and downstairs on 70°

Down 79
up 83

I literally typed in your post into chat GPT:

Imagine your house is like a giant sandwich.

Heat rises. Always. Like how steam goes up from a hot bowl of soup.

So in summer, the upstairs gets hotter than downstairs — just because it's higher up.


Now let’s talk about the AC (air conditioning) in your house:

It’s trying to cool everything down — like putting an ice pack on the sandwich.

If your upstairs is hotter, then your upstairs AC has to work harder to cool it down.

So what should the thermostats do?
You might think:

“I’ll make the upstairs colder than downstairs so the heat doesn’t rise up!”


But here’s the twist:

If you set the downstairs colder, your AC unit there will run longer, and that helps push cold air upward — fighting the heat rising effect.

Meanwhile, the upstairs AC will run less because it’s getting some help.

Think of it like teamwork:

Downstairs AC is like a big fan that pushes cool air up the stairs.
If it runs longer (set colder), it helps upstairs, even if that seems backwards.


TL;DR (Too Long; Didn’t Read):

Heat goes up, so upstairs is hotter.

Making downstairs colder makes the cold air move up, helping upstairs too.

That’s why the internet says set the downstairs lower, even if it feels weird.

My nest app shows me how long each unit runs

They only run about the same time when the downstairs is 2 degrees, sometimes 3 cooler.

I usually put upstairs at 77/78
Downstairs at 75/76

Bofe at 72° here!

Same here.....my experience tells me to set the thermostats and leave them alone! Constant Changing the thermostat settings are not good for efficiency....

My power bill has been very good and consistent since we set it and forget it.

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Can someone explain this to me like I am a 12-year old pre-pubescent kid?

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Cold air goes down, hot air goes up. Upstairs cold air will go down, downstairs heat will go up.

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And so if your downstairs is warmer than your upstairs, you're going to be taxing the upstairs unit more… No?

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Sure, but why would you want to balance the wear on the units? They work more efficiently when one is running 24/7 and the other is doing nothing at all.

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get that, so why would you want your downstairs warmer than you're upstairs?

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because it's not always the temperature on your thermostat

Thermostat location is everything.

Remember the number one rule; hot air rises and cold air sinks. If you have an open stairwell the warmer downstairs air that rises to the downstairs ceiling will migrate to the second floor and can easily impact your upstairs T stat depending on location.

Conversely 58-60 degree air coming out of the grilles on your second floor unit is going to sink. It will sink and migrate down to the first level and it too can impact the t stat downstairs.

Stat locations have to be considered. Temp settings have to be considered, as do personal preferences.

I’ve seen cases where the occupant upstairs like it cold at night and keep the setting in 70 in the hot season. The cool air stops downstairs hits the downstairs Tstat and keeps it satisfied preventing the downstairs unit from running at all. The temp at that stat reads 72 but it is 74-75 in the rest of the zone.