Chofu Heater - Heater with connection ports included.  This Chofu model is a precision built wood-burning water heater designed specifically for hot tubs. It circulates water using the principal of thermosiphon (the pumping action created by rising hot water), eliminating the need for a circulating pump or electricity. This heater is a simple solution to the problem of heating a natural soaking tub. It is ideal for those who want to heat with wood and works well with small or medium sized tubs. Great for remote cabins!  Options include stainless steel stove pipe kit of the correct size.