The insulation is why I didn't put one in already. Before insulating, I have to change a bunch of the wiring the previous person did. It is on the face of the studs instead of in between them. Once that is swapped and insulated, then I can worry about the heat. It is a 3 car garage - not a shop per se. If the furnace works, then it will be more than enough - I used the same set up in my old shop/garage and it was amazing. NG prices are going up here too, but still cheaper than propane.