Chofu Instructions

ASSEMBLY OF THE CHOFU WATER HEATER

(illustration A)

1. The grates should be placed in the firebox with the flat, narrow slotted surface facing up. End knobs face toward the back of the stove.
   
   
2. The grates will fit tightly into the fire box. If you have trouble getting them to fit, try rotating them slightly until they drop into place.
   
   
3. The stainless steel pipe adapter is made to fit standard 4" stove pipe. Refer to page 3 for stove pipe installation.
   
   
4. Your CHOFU heater can be set up either parallel or perpendicular to the tub. If you use a perpendicular set-up, cut off the bend in the rubber hose (see illustration B).
   
   
5. PLEASE NOTE: An ash door located under the fire box is not shown in illustration A. It fastens to the door frame with a compression clip. Take off ash door to clean out ashes in firebox.

Installation Instructions for Long Shank Thru-Wall
Tub Ports Used With The Chofu Wood-Fired Heater

Locating Ports On Tub:

NOTE: Several important factors must be considered before installing the through-wall ports used with the Chofu heater. Please read the entire section below before finalizing your decision on port placement.

Bottom Port - Ideally, the bottom port should be located close to the bottom of the hot tub to pick-up cold unheated water, 3½" to 4" (on center) above the tub floor. Since wooden hot tubs have high sides, you have the option of placing the bottom port higher up from the bottom as long as the proper distance between the top port is maintained. Locating the bottom port higher will position the stove higher off the ground, making it a little easier to load, however, this will require making a very thick heater foundation, which may be impractical.

Top Port - The top port must be vertically aligned, directly above, the bottom port. The top circulation pipe on the stove must rise a minimum of 2" up from the heater to the tub, however a rise of 3" - 5" is recommended. This is necessary for proper thermosyphon circulation. The top port must be located at least 4" to 6" below the normal water level to prevent the port from ever being exposed due to extreme water loss from splashing or overflow from body displacement.

Distance Apart - The minimum distance allowable between ports is 8", however the optimum distance is 12" - 14" apart (on center). The bottom circulating pipe can slope up or down to the tub, however if the proper distance between ports is established it will usually slope down. NOTE: If PVC pipe is used to extend the distance between tub and heater, the distance between ports can be increased.

Heater Foundation - The foundation must be built at the appropriate height to provide the proper slope for the circulating pipes, as indicated above. Use non-combustible materials such as bricks or concrete.

(illustration D)

1. Place heater on a level, non-flammable surface (brick or cement). Be sure this surface extends out in front of the door where sparks or hot coals could fall out.
   
   
2. PLEASE NOTE: A level surface is crucial to proper performance. Several design features are built into the heater to provide effective circulation through the water jacket; they require the heater to be level to properly function.
   a. The back legs are 5/8" higher than the front legs to allow heated water to flow out the top port and into the tub.
   b. The hollow smoke baffle is slanted to allow water to circulate through it.
   
   
3. The heater may be positioned either parallel or perpendicular to your tub. Cut off the bend in the rubber hose for a perpendicular hook-up.
   
   
4. Refer to illustration B for assembly of the connecting hoses, extension tubes, and through-wall connecting ports. Make sure you insert the extension tubes into the corrugated rubber port sleeves as far as possible. The fit should be snug.
   
   
5. The distance between the heater and tub may be adjusted by sliding the stainless tubes inside the rubber hoses.
   
   
6. The corrugated rubber sleeve on the through-wall connecting port can flex to give the desired angle to the heater (up to 20º).
   
   
7. If you need longer pipes for connecting the Chofu to your hot tub, use 1-1/2" PVC pipe instead of the stainless tubes provided. Insulate long pipes with foam pipe insulation.
   
   
8. We recommend 8' of 4" stove pipe and a minimum of 6'. Secure all connections above the stove with three sheet metal screws per section. This is necessary to prevent stove pipe from falling over due to wind.
   
   
9. Circulation ports will have to be drilled through a stave of the hot tub in the proper places using a 2½" diameter hole-saw.
   
   
10. Locate the hot water port on your tub approximately 4" to 6" below the normal water line (typical water level is aprox. 4" below the top of the hot tub). The hot water port must never be exposed during operation. The hot water port may be lower as long as the pipe rises up at least 2" to the tub.
    
    
11. Locate the cold water port near the bottom of the tub, preferably 3" - 4" on center from the bottom.
    
    

Port Installation Procedure:

1. Vertically align position of port holes. Both ports should be centered on the same stave of the hot tub.
   
   
2. Cut (two) 2½" diameter holes in the tub wall.
   
   
3. Place port fixture through hole with rubber gasket between the port flange and inside of the tub wall. Tighten nut on outside of tub wall snugly, so that the rubber gasket is slightly compressed for a watertight seal.
   
   
4. Connect plastic pipe stubs on ports to short rubber flex connectors. Fasten with water hose clamps provided.
   
   
5. Connect the other end of the short rubber flex connectors to the stainless steel connecting tubes (provided); use wire clamps. For a longer length connection between heater and tub, you can replace the stainless connecting tubes with 1½" PVC plumbing pipe. Long PVC pipe should have pipe insulation to prevent heat loss.

(illustration B)

OPERATING INSTRUCTIONS

The CHOFU water heater burns wood, paper, coal, presto logs etc. Do not burn plastic or beach wood containing salt as they may be harmful to the heater.

1. When heating your hot tub, prop the door open with lever on top of door. This provides maximum air to the fire box and therefore, the hottest fire. This also creates the cleanest burning fire with less smoke.
   
   
2. When the tub is up to the desired temperature, close the fire box door. The air space under the door provides air for a slow burning fire while using the tub. Stir the water with a paddle to mix the stratified temperature
   
   
3. Keep in mind that a small fire is required to offset the heat loss while using the hot tub.
   
   
4. CAUTION: Always keep the water level in the tub two inches or more above the top port when in use. If the water level should fall below this port, the normal escape of hot water from the stove will be stopped, which could result in injury from boiling temperatures or possible damage to the heater.
   
   
5. CAUTION: During freezing temperatures always drain the water from the heater by unscrewing the drain plug in the back of the heater, Failure to do this may damage the heater. NOTE: By inserting rubber drain plugs in both ports you can save your heated water and drain just the water in the heater.

PLEASE NOTE: The moisture content of the wood you burn has a significant effect on heating time. Dry, seasoned wood is much preferred. Green or wet wood will heat much slower and may have such a high moisture content that water vapor will condense on the firebox walls and run out under the door. If this happens, don't be alarmed, it is not a leak in the heater.

MAINTENANCE

The only maintenance required is periodic removal of ashes from on top of the baffle and from under the grates. *

CLEANING PROCEEDURE

1. Baffle chamber - Remove the front cover plate to the baffle. With the long-handled scraper we provide, rake out the ashes into a dust pan. Another helpful cleaning tool is a toilet bowl brush for sweeping out remaining ashes and loosing creosote scale.
   
   
2. Firebox - Rake out ashes from under the grates into a dust pan. Brush all surfaces with a toilet bowl brush. Remove the grates for a more thorough cleaning.
   
   
3. With daily use, clean the heater once a week to maintain proper efficiency. Clean monthly if used less frequently.

* NOTE: A thin coating of creosote on the walls of the firebox is a normal condition. Don't be alarmed by this or try to remove it. A constant layer of creosote is always maintained by the fire and does not interfere with performance.

Freeze Protection for the Chofu Wood-Fired Heater

The Chofu Heater must be protected during freezing temperatures to prevent damage. Draining the hot tub will drain most of the water out of the heater, however you must remove the drain plug located at the bottom rear of the heater to completely drain the heater. The bottom line is, if water is kept in the hot tub during freezing temperatures, the Chofu must be protected. Hot tub water will "reverse thermosyphon" through the Chofu's water jacket and provide minimal protection for a short duration of time during freezing temperatures, however with sustained sub-freezing, the heater must be either drained or covered to prevent water in the Chofu water jacket from freezing. As water crystals freeze they grow and expand slowly over time, water in the Chofu water jacket can freeze for a short duration of time without damaging the heater, however if left unprotected, the ice crystals will expand and damage the heater. Draining can be accomplished by inserting plugs (provided) in the circulation ports and then removing the threaded plug at the bottom rear of the heater. CAUTION: Always place the heater drain plug on top of the heater as a reminder that it's been drained. Lighting the heater when empty of water will create an extremely dangerous situation and damage the heater. Since

CAUTION: To be safe, don't let water in the heater freeze even for a short period of time. Freeze damage to the Chofu Wood-Fired Heater is not covered by the warranty. Never light a fire in the Chofu with ice in the water jacket. This will damage the heater and create an extremely dangerous situation of trapped steam. If the Chofu accidentally freezes, place it in a warm room or insert a light bulb inside the firebox to melt the ice. Completely thaw before using.

Draining the Heater

If water is left in the tub during freezing temperatures, plugs can be inserted in the through-wall ports and the Chofu Heater drained by removing the drain plug in the back. CAUTION: Since there is no visible indication that water has been drained from the water jacket, you must provide yourself with a visual reminder. Always place the black drain cap on top of the stove body, so it will be seen before lighting a fire. Making a fire in the Chofu when the water jacket is empty will damage the heater. The thermosyphon circulation of water through the water jacket, constantly cools the metal, however, without water, the inner wall of the water jacket (in contact with the fire) will rapidly over-heat and warp.

Covering the Heater

Another way to protect the Chofu from freezing is to build an insulated box that fits over the heater and snugs-up to the tub. The stove pipe must be removed to do this. (Lift off the stove pipe at the connection between the black enameled smoke outlet and the stainless pipe adapter above it. This connection doesn't need to be fastened for stability.) An external heat source (light bulb or heat tape) may be required to keep the temperature inside the box above freezing.

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