Chofu Propane Water Heater

The Chofu Propane Water Heater is not available at this time. If you are interested in this model and would like to be put on our waiting list, please complete the form below and let us know. Thank you.

The Chofu Propane Heater is a high efficiency water heater designed specifically for hot tubs. Like the Chofu Wood-Fired, the Propane Heater circulates water by thermosiphon (the pumping action created by rising hot water, see illustration), eliminating the need for a circulating pump or electricity. This revolutionary concept enables you to have a simple soaking tub without jets, chemicals, etc. With a Chofu Heater you can retrofit an existing tub or put together your own low-cost soaking tub, using a wooden tub or stock tank.

The Chofu Propane Heater greatly reduces hot tub maintenance, since it has no moving parts and requires no electricity. It’s designed for outdoor use, with a durable powder coated steel outer casing and a stainless steel exhaust cowling.

Inside the Chofu is an elaborate network of copper tubes with heat collecting fins, that are heated by six stainless steel burners. The configuration of the copper tubes is designed to create thermosiphon circulation by allowing the heated water inside the heater to rise up and flow into the tub.


The Chofu connects to a tub with provided accessories (see connection kit): flexible neoprene tubes, stainless steel pipes, and thru-wall tub-ports.
Installation Sequence:
(1) The heater is placed on a brick or cement foundation next to the hot tub.
(2) 1 7/8-inch holes are cut in the side of the tub wall to receive thru-wall ports.
(3) Connecting pipes are assembled between heater and thru-wall ports. (Connecting clamps are fastened with a screwdriver.)
(4) The heater is connected to a propane source, either a portable or permanently installed propane tank.


The Chofu heats water on-demand, the day it is needed. (It does not have a thermostat). The heater is operated manually with an automatic ignition switch, however, it uses a spring wound timer to control the duration of heating and to automatically turn off the heater. The main control switch for the heater is designed to be mounted on the side of the tub, for easy access in or out of the tub. If water in the tub looses too much heat while it’s being used, it can quickly be brought up to temperature without having to step out of the tub.


  • Operates without electricity
  • Automatic ignition switch
  • Automatic heating timer
  • Tub mounted remote control switch
  • Drain valve for freeze protection
  • Weather proof housing
  • Safety shut-off for over-heating.


  • Dimensions: 17″ high x 17″ long x 10″ wide
  • Weight: 19-lbs.
  • Stove Body: Powder coated steel
  • Circulating Pipe Dimensions: 1 1/2-O.D.

Heating Schedule

The Chofu puts out 30,000BTU’s. A 200-gallon tub can be heated at approx. 20ºF per hour.

55ºF to 105ºF

Gallons Time
100 1 1/2 hours
200 2 1/2 hours
300 3 1/2 hours
400 5 hours


The Chofu Propane Heater must always be protected from freezing to prevent damage. We provide special through-wall ports with threaded plugs that allow you to keep water in the tub, while draining just the heater during freezing weather. Plugs are inserted into the ports and water is drained out of the Chofu by removing the drain cap from the Freeze Protection Drain Pipe.*It must be noted that firing-up the Chofu, when it is empty of water will quickly damage the heater. The Chofu Propane heat exchanger/water jacket must always be filled with water, and the tub ports open to allow water to circulate through the water jacket, and therefore, cool the heat exchanger metal.

*The Chofu Propane Heater does not have a built in drain plug, therefore, a Freeze Protection Drain Pipe must be used to drain the heater during freezing weather. This pipe replaces the bottom stainless steel circulating pipe. If you do not have this item, please contact Island Hot Tub Company: 1-888-878-5512.

Alternative Freeze Protection Methods

  • Drain the Tub – This will also drain water out of the heater, however, the bottom circulating pipe on the heater must slope down to the tub to completely empty the heat exchanger/water jacket of the heater.
  • Covering the Chofu – This method can be used instead of placing plugs in the through-wall ports and draining the Chofu, however, it requires that you make an insulated cover that can be placed over the Chofu*. This may be adequate protection during night time temperature drops just a little below freezing. For long term protection, the enclosure must have an external heat source, such as a light bulb or heat tape. The tape can be wrapped around the bottom stainless circulating tube, causing heat to rise up through the water jacket and into the tub.

A protective cover may be either a soft insulated (tea cozy) type or a hard shell, wood structure. To provide complete freeze protection, the enclosure must snug up against the tub to protect the circulating pipes, as well as the heater.

The Chofu Propane Water Heater is not available at this time. If you are interested in this model and would like to be put on our waiting list, please complete the form below and let us know. Thank you.


Comments or questions are welcome.

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