Quick Answer
Build a wood-fired water heater from scratch by starting with a durable drum or tank, installing stove coils or a thermosiphon, and ensuring proper insulation and airflow for efficient heat transfer.
Drum Selection and Preparation
Choose a sturdy, food-grade drum with a diameter of at least 30 inches (76 cm) and a height of 24 inches (61 cm). Clean and inspect the drum for any rust or damage, and apply a rust-inhibiting coating to the interior surface. Cut a 1-inch (2.5 cm) hole at the bottom of the drum for the water outlet, and another 1-inch hole on the side for the drain valve.
Stove Coil or Thermosiphon Installation
Design and install stove coils that fit snugly inside the drum, ensuring they’re exposed to the heat source. Alternatively, you can use a thermosiphon system, which circulates water through a coil as it heats up. Ensure the coil is designed for high temperatures and has sufficient clearance from the drum’s interior surface.
Insulation, Airflow, and Safety Considerations
Wrap the drum with 2-3 inches (5-7.5 cm) of refractory insulation to retain heat and prevent heat transfer through the walls. Ensure good airflow by installing a chimney or vent system to direct exhaust gases away from the drum. Install a pressure relief valve and a temperature gauge to monitor the system’s performance and prevent over-pressurization.
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