Garage Heat

Well Im leaning toward the house furnace and running the vent out side. Its a detached garage so Im not running gas out there even though it would infact be cheaper. I think they would both work. I wont run a wood burner sorry but seen way to many bad scenes from them.

One thing to consider... If you did run gas out there... You could keep the garage semi warm (like 50-60 degrees) all winter at a low cost. (assuming your insulated) This will be better for your cars then the freeze/thaw/freeze/thaw of going out there and heating up the garage for a few hours at a time.