Power-Pipe R3-42 Drain Water Heat Recovery Unit Lowest cost and shortest payback on your money amongst water heating saving technologies The R3-42 will Save Up To 28% on your Water Heating Costs and is easy to install by any Plumber and Most Do-It-Yourselfers All residential (R-series) units include matching drain connectors and connect easily to a 3/4 in. fresh water line For 3 in. drain pipe and requires a vertical drain pipe length between fittings of at least 45 in NOTE: According to NRCan Sept 2008 with the R3-60, performance is proportional to rated efficiency