Shop heater

[real550A]

"I like the natural gas furnaces, cheaper and faster heat. "

I agree that natural gas is good heat, if you're in an urban setting where it is available, and you're heating a building w/an existing slab. No city gas out here in the woods.
As far as cheaper, that's on a case by case basis. We have a 780 gal. wood fired, outside boiler that heats a home and 2 outbuildings. Due to a tornado last July, the fuel
has been decidedly cheaper than any "store bought" fuel available, and will be for the next 30 years.
I also like the "silent mode" of the slab heat. You literally can hear a pin drop in our shop!