I have 3 units - 3ton for all of upstairs and 2 2ton units zoned for downstairs covering 4300 sq ft with 9ft ceilings down / 8ft up.
I have all three on programmable thermostats with the usual 4 different time of day settings.

My question is what is a best practice for setting my thermostats? Now, for the summer I am running the upstairs at 82 degrees with the down set at 80 (both units). It seems the up unit runs a lot. We are comfortable downstairs where we live most of the time (we don't do much upstairs during the summer). I worry that I've set the down units too high and it's causing the cool air from up to just pour down and not cool the up very well causing the unit to run a lot. The down units don't seem to run too much. Should I set the down units lower to make it cooler to help keep some cooler air up and not cause the up unit to run so much?
Winter time I like to run the upstairs one or two degrees warmer than the downstairs and that seems to help keep the warm air down.

Thanks!

Warm air rises, cool air falls... always. Nothing you can do about it except blow it around with fans. Upper levels always require more cooling because of this stratification. You may want to try running the furnace fan(s) continuously. This will help the circulation and actually keep the air a bit cleaner. You will most likely have to change the filters more often if you do that.

Thanks for the suggestion.
I was just wondering if there was any validity to my idea of actually keep the downstairs cooler that it would keep the upstairs cooler. Y'know, create a cushion of cold air to keep the cool air from up falling. I think I might be thinking about this too much, ha-ha.



Warm air rises, cool air falls....always. Nothing you can do about it except blow it around with fans. Upper levels always require more cooling because of this stratification. You may want to try running the furnace fan(s) continuously. This will help the circulation and actually keep the air a bit cleaner. You will most likely have to change the filters more often if you do that.