With an ammo box, mason jar, and copper coil, I constructed an off grid water heater / heat exchanger / space heater.
source/image(PrtSc): The Outsider
Burning a fire in the coil to heat cool water,used as heat exchanger,utilizing thermodynamic nature circulation cycle principle to heat the water in the tub.Watch the video from The Outsider for more info:
Circulate the water through the coil(water comes in at the bottom of coil,heats up,and thus absorb heat energy from hot coil tube,and then flows out at the top back into the tub),thus also named Hot tube heater coil.
Whether you need hot water for heating or hot a shower, cleaning up dishes, or washing clothing, this off grid heater gives you control and flexibility, allowing you to preset the temperature you need.