What Is a Wood Fire Soaking Tub?

A wood fire soaking tub — sometimes called a cowboy hot tub — is a large stock tank traditionally used for cattle water, repurposed as an outdoor soaking tub heated by a wood-burning firebox. You fill it with water, carry wood from the pile, build a fire, and wait for the water to heat up. Then you soak under the open sky. It can also be used as a cold plunge — simply fill, skip the fire, and jump in.

It's one of the most uniquely Utah experiences you can have. Most of our cabins include a seasonal wood fire soaking tub, available spring through fall. From the time you start filling to the time you soak, expect the whole process to take about 1.5 to 2 hours — plan ahead and you'll time it perfectly with the sunset.

🪵 Firewood

Bring your own wood or purchase access to ours — just $15 per night for the wood pile. You'll carry it to your tub and split it to size. First time? Let your host know before you start — they'll walk you through the whole process.

The Tubs at Starlit Ridge

5 cabins with private wood fired soaking tubs · available spring through fall · View all cabins →

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Please Read Thoroughly Before Use Safety Warnings
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Never light the Chofu firebox without water in the tub. The firebox walls are continuously cooled by water circulating through the water jacket — without water, they will overheat and the heater will be damaged. Water must cover the top port by at least 4 inches before lighting. Water near the inlet port may be very hot while heating; be cautious.
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Do not use the tub during an electrical storm.
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Do not use the tub under the influence of alcohol or drugs.
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Do not use the tub if the thermometer reads above 104°F.
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Do not enter if you are feeling lightheaded. Exit the tub immediately if you begin to feel overheated while soaking.

Tools & Supplies

Everything you need should be in the deck box and around the tub. Check for all items below before you start. If anything is missing, contact your host before proceeding — don't improvise with missing safety equipment.

🧰 In the Deck Box
🔨Hammer
🪓Hatchet
🔥Lighter
🍳Mixing paddle
🫙Colander (for sifting)
🧹Brush & dustpan
🌡️Thermometer
Also on deck: fire stoker (next to the Chofu heater). You can use your own firewood or purchase access to ours for $15/night. Missing something? Let your host know.

How to Use the Tub

1
Check the Water Supply

The water supply to the hose should always be on. Turn the lever on the hot tub end of the hose to start the water flowing.

2
Check Your Tools

Before anything else, confirm all tools are present — hammer, hatchet, lighter, mixing paddle, colander, brush and dustpan, and thermometer in the deck box; fire stoker next to the Chofu heater. If anything is missing, contact your host before proceeding.

3
Rinse the Tub

This is an off-grid tub — it may have some dirt and debris inside. Open the drain on the right side of the tub first. Switch on the hose and spray the tub out. Use the brush and dustpan to scrub as needed.

4
Close the Drain

Once the rinse is done, close the drain on the right side of the tub. Make sure it's fully sealed before you start filling.

5
Fill the Tub

Start filling with the hose and set a 30-minute timer — this should bring you close to the fill line.

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Do not light the Chofu until water covers the top port by at least 4 inches. The firebox walls rely on water circulation to stay cool — no water means permanent damage.
6
Clean Out the Ash Tray

While the tub is filling, pull out the ash tray from the bottom of the Chofu heater. Check that there are no hot coals. Use the ash rake and dustpan to scrape out all ash from under the grate — this clears the airflow path and is essential for a strong fire. Toss the ashes to the side; they're great for plants.

7
Carry and Split Your Wood

Collect your firewood from the wood pile on property and carry it to your tub. Using the hatchet and hammer, split it into two types:

Kindling: About 10 thin, slender sticks to get the fire going quickly.

Fuel logs: About 15 pieces at roughly 16–17" long × 2" × 2" or smaller — the Chofu heats faster and burns cleaner with long, slender pieces that create a roaring hot fire. Large chunks burn longer but slower and reduce heat output.

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Please split wood on a nearby railroad tie — not on the deck.
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Drive the hatchet with the hammer through stubborn logs — short controlled strikes are safer than swinging freehand. First time? Ask your host to walk you through it.
8
Light the Fire

Once the water covers the top port by at least 4 inches, you're ready to light. Place a large amount of wadded-up paper on the grate, then cover with slender pieces of split kindling — leave air space between pieces so the fire can breathe.

Light the paper in several places across the front. Leave the door open at this point to encourage the fire to catch. Keep adding small pieces of wood until you have a blazing fire going.

Once the fire is well established, begin adding your larger fuel logs. Don't add too much wood too soon — it smothers the fire. Build up gradually.

9
Build Up the Fire — Door Technique

Once the fire is going strong, close the door — but not completely. Leave a small air gap at the top with the hand lever resting against the post. Open the dial draft in the door fully. This gives the fire maximum airflow.

Build up multiple layers of wood across the firebox, leaving space between each piece so the fire can engulf it. Think of creating many small chimneys for the fire to travel through. Tightly packed wood will burn slowly. Once the fire is really roaring, you can completely fill the firebox — still with space between each piece.

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The Chofu heats best when the fire is roaring and the water jacket is making a hissing sound. That sound means it's working hard. Don't be timid with the wood at this stage.
10
Mix, Check Temp & Reload Every 30–40 Min

The Chofu uses thermosiphon circulation — no pump — so hot water rises to the top and cold stays at the bottom. Always mix with the paddle before reading temperature, or you'll get a false high reading.

Check temperature: dip only the probe end of the thermometer — do not submerge the dial.

Reloading: Let the fire burn down until you see just radiating coals. Use the ash rake to pull the hot coals toward the front. Then reload with multiple layers of wood, leaving air space between each piece. Reload at 30–40 minute intervals.

11
Slow the Fire as You Approach Temperature

Around 95°F, start slowing the fire down — you've built up a large bed of hot coals that are still putting out significant heat. Don't refill the firebox at this point. Instead, add a partial load or a few larger, slow-burning pieces that will sustain warmth once you're in.

Reduce heat output by using less wood and restricting airflow into the firebox.

As the water approaches 104–105°F, close the door completely using the hand lever and partially or fully close the dial draft. Once you're in the tub, a small fire is enough to offset the heat loss from bathing — knowing exactly how much takes a little experience. That's the art of the Chofu.

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Common mistake: Adding too much wood as target temperature approaches. It's easy to overshoot. If the tub gets too hot, stir thoroughly first to get a true reading, then add cold water slowly if still needed.
Below 95°
Keep feeding — build a roaring fire
~95°F
Slow down — partial loads only, restrict airflow
104–105°F
Close door & draft — do not enter above 104°
12
Hop In & Maintain

Once the temperature is comfortable for you, get in. Keep a small, slow fire going to offset heat loss while bathing. Continue mixing and checking temperature periodically — exit immediately if you feel lightheaded or overheated.

13
Return All Tools

When you're done, return all tools and materials to where you found them so everything is ready for next time.

⚠️ Don't Drain Until the Fire Is Fully Out

If the fire is still burning when you're done soaking, leave the water in the tub and drain it the following morning. With the door latched and vents closed, limited airflow will let the fire die out naturally and safely.

Do not pour water into the Chofu firebox to extinguish it. This adds humidity to the firebox and makes it very difficult to light on future uses.

Once the fire is fully out, open the drain and empty the tub.

Rookie Mistakes

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Not filling the firebox enough

Once the fire is going, load it up. The Chofu heats best when the fire is roaring and the water jacket is making a hissing sound — that sound means it's working hard. Timid fires mean long, slow heat-ups.

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Overheating — too much wood as target temp approaches

It's the most common mistake. You have a big bed of hot coals still radiating heat — adding a full load of wood near the finish line will push the temp well past 104°F. If you overshoot, stir the water thoroughly first for a true reading, then add cold water slowly if still needed.

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Time It Right for the Stars

The whole process — fill, fire, heat — takes about 1.5 to 2 hours. Start as the sun gets low and you'll slip into a hot tub right as the sky goes dark. At almost 8,000 ft in a dark sky corridor, the Milky Way comes out roughly 90 minutes after sunset. Step away from your screen for 15–20 minutes and let your eyes fully adjust — the difference is dramatic.

If you're prepared to stay up late for the darkest sky, check the moon calendar for the darkest window tonight — a new moon means an extraordinary show.  Moon phase calendar ↗

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