From Guest Blogger Brian McGowan: Heat Recovery Device — Should I Do It?
Quite a few years ago I thought it would be good to recover heat from drain water since heating water is very energy intensive. A couple of my plumber friends and I discussed several ways to do it trying to account for all the problems that might be encountered. Then one of them went to a plumbers trade show and found a simple drain water heat exchanger. It was a piece of 4” copper pipe with ½” copper water pipe wrapped around it the idea being to run cold water through the ½” pipe from bottom to top and warm it up before feeding it into the hot water heater thus recovering the heat and saving energy. When I had sewer installed in my house in 2005 I ordered one of these and had the sewer installers put it in the vertical drain line. In April of 2007, when I had time and a friend who was faster at soldering than I was could help, I hooked it up. Pictures of that installation are here. (more…)