This heater has kept me warm in a 200 sq ft camper all winter comfortably. Efficient on fuel if it on idle and will throw serious heat when fully on. It uses little amperage on idle but 10 to 20 amps when fully on. I would like to see spare parts available though. There are simple ways to make it more efficient with a planned install. Such as a larger metal pipe over both the air intake and exhaust which acts as both a heat shield and fresh air pre-heater. This will keep the heating chamber at a higher consistent temperature, which will also help for a cleaner burn of the fuel.