Energy-Efficient Hot Water Piping Systems

If you plan to build a new home, pay close attention to the design of your hot-water piping system. A long wait to get hot water–30 seconds or more–is a common complaint in even the best new homes. Today’s new homes are larger and the plumbing fixtures are more spread out, creating these longer waits, wasting water, and wasting the energy used to heat water.

To minimize these types of loss, the most important decision in new home design is the location of your water heater. It should be centered among the plumbing fixtures for optimal efficiency and performance. Smaller diameter pipes, such as 3/8 inch rather than 1/2 inch, are sometimes used to feed far-flung fixtures and so speed hot-water delivery. Since these smaller pipes hold less water, you’ll run less water down the drain while waiting for hot water.

Be sure to insulate all of your hot-water pipes whether you are building a new home or improving the efficiency of an existing home. If you are building a new home on a concrete slab foundation, insist on insulation for hot water pipes traveling through the slab, since these are one of the most common causes of long waits for hot water.

If your bathrooms and kitchen are more than 25 feet from one another, consider ask your plumber about installing a hot water re-circulation pump that operates on demand. A demand re-circulation pump senses when you need hot water and rapidly pulls hot water out of your water heater and distributes it to your fixtures, while at the same time pushing the cooled water in the pipes back into your water heater. Recirculation systems reduce the time you must wait for water, and they eliminate the waste of water that normally takes place when you purge your water lines while waiting for hot water to arrive at each fixture. Note that continuous re-circulation pumps, such as used in hotels, aren’t recommended because they run 24 hours per day incurring a large energy cost.

The Homeowners Handbook to Energy Efficiency contains simple, practical energy-efficiency ideas.