unfortunately if your garage isnt insulated decently, heating it will be a issue. i had to run a 150k forced air kerosene heater in my 20x22 to keep warm before i re did the garage. fumes sucked, , no real temp control. if you turned it off it would get cold quick. best thing i ever did was insulate the garage. now i can leave my wall unit on setting 3 and she gets warm pretty quick. i had to put a fan up top to circulate heat. works great. in your situation, unless you insulate you need somethign small you can direct heat onto you. try one of those Mr.Heater Big Buddy heaters http://www.tractorsupply.com/mr-heater-reg-big-buddy-trade-portable-heater-18-000-btus-2133493 infared panels, and has a built in electric fan. the propane isnt very noticeable smell wise.