Can Single-Pipe Systems Work for Drainback Applications?

System Design Considerations

When designing a single-pipe drainback system, it’s essential to consider the system’s ability to prevent freezing. One effective approach is to use a “cold-water sink” at the bottom of the system, which allows the drainback fluid to flow to the ground and not into the collector loop. This can be achieved by installing a drain valve and a cold-water return line that connects to a nearby drain or a ground-based drainback tank.

Freeze Protection Techniques

To protect the system from freezing, install a freeze protection valve that can detect when the system temperature drops below a certain threshold. This valve can be set to automatically shut off the collector loop when the temperature falls below 32°F (0°C). Additionally, consider installing a heat source, such as a backup electrical heat strip or a propane heater, to provide warmth to the system during extremely cold weather.

System Sizing and Configuration

When sizing a single-pipe drainback system, it’s crucial to consider the collector loop size, pump size, and valve sizes to ensure efficient operation and prevent system freezing. For example, a 2-inch (50 mm) collector loop may require a 3/4-inch (20 mm) drainback pipe to prevent freezing. The system should also be configured to allow for proper drainage and prevent water from accumulating in the system. Consider using a drainback tank with a capacity of at least 20 gallons (75 liters) to provide a buffer during cold weather conditions.