We have 1600 sq ft two story tract home. The forced air HVAC system (Carrier) was new in 1994. We have always had a problem with the temperature differential between upstairs and downstairs being somewhere between 5 to 10 degrees. At first we closed the HVAC vents upstairs or downstairs depending on the time of year. Then we put in ceiling fans, that helped some, but we really need a way to pump the trapped hot air from the second floor to the first floor in the winter and the opposite in the summer. Short of replacing the entire heating system is there any simple way to resolve this. I was thinking of trying to put in a duct between floors with low speed fans, but I am sure there would be a fire code restriction. Any ideas?? If we resolve this in my home there are several in he neighborhood that have the same issue.