I am building a new pole barn shop with metal sides and I want to put my old King heater in there for a little heat. What is going to be the best way to route my pipe and not burn down the whole place and maintain as much heat as I can. I thought about getting out away from the wall a few feet going straight up about 10 feet, putting a 90 in and turning it through the wall then turn up again outside the wall and go up above the ridge height. The shop has 12 feet walls. I really hate to go through the roof because of leaks.