I have a 2-car garage in Albemarle, NC (about an hour NE of Charlotte). My advice would be to spend your $'s on insulation and sealing it up and you won't need much heating or cooling to be comfy. I heat my garage with a 1500 watt floor heater from Walmart or Target. I cool it with a window air conditioning unit. Just be sure walls and ceiling are insulated. Insulated doors would be nice but I don't have that yet.
Conrad Carter
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