Hybrid vertical drainpipe heat exchanger

Abstract

A low-cost hybrid heat exchanger uses sheet copper and rigid plastic tubing. Copper is used only where actual heat transfer takes place, adjacent the drainpipe wall. All other components are plastic to lower cost. It pre-heats fresh cold water using waste heat from the drain such as from a shower drain. The heat exchanger comprises an inner copper conduit or drainpipe, a rolled sheet copper cylinder, an outer plastic tube and manifolds, and O-ring. On assembly, inserting the drainpipe results in the O-ring being compressed between the copper cylinder and the plastic tube. The result is a sealed water chamber wherein heat transfer takes place. The ends of the plastic tube have radially spaced water distribution holes into the chamber and inlet and outlet manifolds, each with water connections to the building's cold water supply. A method of recovering heat from non-shower hot water uses using a separate reservoir is also disclosed.

I claim: 
     
         1 . A vertical drainpipe heat exchanger for transferring heat from a drainpipe, said drainpipe heat exchanger comprising:
 a conductive layer surrounding said drainpipe;   a gasket spacer, said gasket spacer having channels to permit flow of fluid therethrough adjacent said conductive layer; and   an outer cylinder surrounding said gasket spacer, an inlet and an outlet within said outer cylinder to permit fluid access to said channels.   
     
     
         2 . The vertical drainpipe heat exchanger of  claim 1  wherein said conductive layer has a vertically extending opening therein. 
     
     
         3 . The vertical drainpipe heat exchanger of  claim 1  wherein said gasket spacer comprises an upper ring, a lower ring, and a plurality of legs extending therebetween. 
     
     
         4 . The vertical drainpipe heat exchanger of  claim 2  wherein said outer cylinder has a plurality of inlets and a plurality of outlets to permit fluid access to said channels. 
     
     
         5 . The vertical drainpipe heat exchanger of  claim 3  wherein said conductive layer has a vertically extending opening therein, said conductive layer having a flange adjacent said opening, said legs of said gasket spacer being located adjacent said flange and said opening.