How a Wood-Fired Hot Tub Works
- A wood-fired hot tub uses the heat generated by burning wood to warm the water. It does not require electricity or gas, making it an ideal solution for outdoor bathing, camping, resorts, and off-grid wellness spaces.
- Wood Burning Generates Heat
- Firewood is placed inside the wood stove and burned.
- The combustion process produces heat.
- The heat is transferred through the stove body, heat exchanger pipes, or water jacket system.
- Heat Transfer to the Water
- There are two common heating designs:
- ① Internal Wood-Fired Heater
- The stove is installed inside the hot tub water area.
- Water directly absorbs heat from the stove surface.
- Advantages: Fast heating and simple structure.
- Disadvantages: Takes up space inside the tub and requires safety protection.
- ② External Wood-Fired Heater (Most Popular Design)
- The wood stove is installed beside the hot tub.
- Water flows between the tub and the heater through inlet and outlet pipes.
- Cold water enters the stove heat exchanger.
- The heated water returns to the hot tub.
- Water circulation process:
- Cold water → Heat exchanger → Heated water → Return to hot tub → Water temperature rises continuously
- Natural Water Circulation Principle
- Many wood-fired hot tubs operate without a water pump by using natural convection:
- Heated water becomes lighter and rises.
- Cooler water sinks and flows into the heater.
- This creates continuous natural circulation.
- A circulation pump can also be added to improve heating speed and maintain an even water temperature.
- Temperature Control
- The water temperature can be adjusted by:
- Adding more or less firewood.
- Controlling airflow into the stove.
- Monitoring the water temperature with a thermometer.
- Recommended bathing temperatures:
- 37–40°C (98.6–104°F): Comfortable wellness bathing
- 40–42°C (104–108°F): Hot soaking experience
- Advantages of a Wood-Fired Hot Tub
- No electricity required
- Low operating cost
- Perfect for outdoor and off-grid use
- Creates a natural hot spring experience
- Ideal for gardens, cabins, campsites, resorts, and wellness centers
