Cooler temperatures aren't here yet, but it's worth researching ahead of time if you're in need of a furnace upgrade. Fortunately, the market these days is flooded with options. To pick the right one ...

Q. I made energy improvements to my house, but my 25-year-old gas furnace does not keep it as comfortable as before. Also, I think my gas bills should be lower? Which 2008 furnace models are most ...