Diagram of trunk and twig recirculation system with demand pumps, and a photo of Gary Klein


Protocol for Evaluating the Layout of a Hot Water Distribution System -- Gary Klein describes a series of tests taken at different hot water taps that will determine what the piping layout is, even if it's hidden behind walls. These measure flow rate and volume and can help determine if a demand pump is needed.

What Do Consumers Want From Their Hot-Water Systems? -- This is a three-part series comprising Consumer Expectations, Distribution and Central Core Plumbing.

Efficient Hot Water Piping -- What is best? Manifold system? Full-time recirculation? Demand pump? This article delves into these issues and examines the elements that result in quick and efficient hot-water delivery. Those include plumbing layout, piping size and type, velocity and flow rate, and considerations of what is specified by the Uniform Plumbing Code.

Optimizing for High Performance Solar Water-Heating Systems, Part 1 -- How to size the solar portion of the system and ways of improving efficiency.

Optimizing for High Performance Solar Water-Heating Systems, Part 2 -- A look at the issues and options surrounding the choice of the best supplemental heater.