[jyl]

I had planned to install mini-split AC units in the upstairs bedrooms, where the central AC doesn't cool effectively (small ducts, no returns).

Now I'm thinking I should make those mini-split style heat pumps to both cool and heat those bedrooms. The main forced air gas furnace doesn't do a good job of heating those rooms.

The idea being that the main forced air gas furnace and central AC would then only be used to heat/cool the ground floor, which it does well (larger ducts and returns), while the heat pumps would do the job of heating/cooling the upstairs. At night I could program the main furnace to hold the ground floor at a chilly temperature, while the heat pumps keep the occupied bedrooms warm, and the unoccupied bedrooms are not heated.

I want to keep the gas furnace because I can run it on a generator when we lose electricity, which happens (occasionally, but can be for days at a time) in the winter. I am not willing to go "all electric", partly for power outage reasons and partly because our electric utility is raising rates like crazy (+20% this year). I wouldn't need the heat pumps to work well when it is very cold outside, since we can always crank up the gas furnace during those periods, although it would of course be nice if they did.