We want to insulate and turn our 2 car garage into live-able space however I am concerned about the additional 361 sq. ft and its impact on our Gibson heating and AC unit model#Glira072c-12A. It will bring our sq.ft to 2156. We plan on bypassing our small laundry room vent and extending 3 ft into the garage ceiling but I dont know if our existing furnace/ac unit can handle it. Our house is 5yrs old (as is the unit) and is located in Northwest Florida. So we have hot summers and in winter it can get as low as 20 degrees at night (but not often) I cant find an online btu conversion chart as I cant figure out my units BTU output or input or whatever! The little manual that was left with the unit is Greek to me (and my husband ) ... Please advise, Thanks!