Quick Answer
For a DIY thermosiphon water heater, use a 3/4 inch copper tubing, a 50-gallon tank, and a black steel or cast iron stove coil with a 1/4 inch NPT thread. Ensure the coil is submerged in the tank and the water level is at least 12 inches above the coil. Monitor water temperature and adjust the stove output.
Designing the Thermosiphon System
When designing a thermosiphon system, consider the tank size and the number of coils. A 50-gallon tank with a 3/4 inch copper tubing and 2-3 black steel or cast iron stove coils is a good starting point. The coils should be spaced evenly apart and submerged in the tank, with the water level at least 12 inches above the top coil. This allows for efficient heat transfer and prevents airlocks.
Coil Selection and Installation
Choose a stove coil with a 1/4 inch NPT thread for easy installation. Use Teflon tape to secure the coil to the tank, ensuring a leak-free connection. For a wood-fired water heater, consider using a batch heater design with a separate combustion chamber. This allows for more control over the heating process and reduces the risk of overheating.
Safety Considerations and Monitoring
To ensure safe operation, monitor water temperature and adjust the stove output accordingly. Aim for a temperature range of 120-140°F (49-60°C) to prevent scalding and bacterial growth. Additionally, consider installing a pressure relief valve and a temperature gauge to monitor the system’s performance. Regularly inspect the tank, coils, and connections for signs of wear or damage.
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