This is my first furnace/ac purchase so go easy. What, exactly, is "variable speed" for the furnace? I have been looking at a Trane XL80 with and without "variable speed". In looking at the product brochure, I see a variable speed draft inducer (listed to the XL90), a two speed draft inducer (XL80), and a multi-speed blower motor. I'm sooo confused.
Also, I'm in a condo unit so the furnace is inside the unit. One installer has mentioned they would be putting extra insulation to make it quieter. How noisy might this unit be compared to a 26 year old General Electric?