It's one of a few projects I would really like to take on, but the effluent drainage in my home (rented) is all cast iron and there is no place to divert it into a heat exchanger tank. To recover heat through the iron pipe would probably require excessively low evaporator temperatures. The only effluent I have access to is the discharge from my washing machine into a mop sink, but we wash with cold water
. I might be able to pull off a small under sink water heater in my kitchen that recovers heat from the drain water under the sink while I do the dishes.