I am going to buy a 2.5 ton air source heat pump for my home in central Florida. The contractors I have talked to disagree on the amount of the KW for the auxiliary heat. Either 8 or 10 KW is what I am told. One said 10 is better for it would heat up faster & then you would switch sooner to the heat pump. Another said it would cost more to have 10 KW. Both are certified Trane dealers. I myself am more concerned about the cost of using the auxiliary heat & would like to minimize that.