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Committee member demonstrates drainage water heat recovery system for homes
Summary
A committee member showed a home-installed drainage water heat recovery system that preheats incoming water by transferring heat from wastewater, describing a roughly $500 purchase cost and a 3to4-year payback when paired with on-demand heaters.
A committee member identified in the meeting as Jodi showed the Energy and Environmental Committee a drainage water heat recovery system installed in her home and described how it raises incoming water temperature by recovering heat from drainwater.
Nut graf: Jodi said the system uses a copper coil placed around a vertical sewer pipe to transfer heat from warm wastewater to incoming cold water, reducing the energy needed to bring water to typical hot-water temperatures. She reported a purchase cost of about $500 and said her system produced a roughly three- to four-year payback when paired with on-demand water heaters and lower household water use.
"This is my house, and what you're seeing, in the copper tubing is a drainage water heat recovery system," Jodi said during the committee's environmental update. She described feeling "almost a 40 degree temperature increase" in incoming water and estimated approximately 68% heat transfer in her installation.
Committee members asked operational questions: whether the system requires copper waste pipe (Jodi said PVC cannot provide the needed heat transfer and that installers supply a copper-lined section), compatibility with gas on-demand heaters (Jodi said on-demand gas or electric heaters work well; conventional tank heaters are less efficient with the device), and seasonal differences in perceived cold-water temperature. Jodi said the manufacturer recommends plumbing all incoming water through the coil for maximum benefit but that her installation only serves the hot-water loop.
Cost and installation: Jodi described the unit's purchase price as about $500 and said installation took about 15 to 20 minutes in her retrofit case; longer, taller coils provide greater heat recovery. She said units come in sections (four, six or eight feet) and that deeper basements allow longer coils and better performance.
Ending: Committee members thanked Jodi for the demonstration and said they looked forward to examples of household energy-saving measures at future meetings.
