Anonymous wrote:My central air unit is too small for the square footage. My house really needs a split unit, but the estimates we've gotten have been around $30,000. NOT doable. We will just have to continue living with an extremely cold house in the winter, and hot house in the summer.

We've started running the fan for fifteen minutes every hour. It has really helped even out the temperature in our house. I don't think our old thermostat could do it, but it is one of the nifty features on the Nest.
We looked into adding zoned HVAC b/c our house was so uneven. The other thing that helped, but is more difficult to do, is we had an air return added in the basement. I don't remember what it cost, but it was not grossly expensive. Would love to add another at the top of the stairs, but that would require a lot of duct work that isn't happening.