Q: Our home is a 3,200 square foot colonial with a finished basement. We've got a problem with a very wide temperature variance on the three levels. This is particularly noticeable during hot summer days when our upstairs level is noticeably warmer than the main level, and the finished basement is noticeably cooler. Currently, we have a single zone central air conditioner (5 ton) with one thermostat on the main level. We are considering the addition of a heat pump (in the attic) to exclusively cool the upstairs level.

However, a colleague suggested something else that we'd like to solicit your advice on. His suggestion is called...