I enjoyed reading Gary Klein’s article on hot-water conservation (“Efficient Hot-Water Piping,” 3/13). This is how I have designed hot-water systems for over 40 years (see blue line in drawing at right):1. Remove the water-heater drain valve near the bottom of the water heater and use that location for the cold-water inlet. Plug the original cold-water inlet.2. Run a 3/4-inch main line and a 3/4-inch return line. Put a spring-loaded check valve in the return line to prevent incoming cold water from entering the return line.3. The return line should drop gradually without bending upward at any point.4. The hot...

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