Patent ID: 6722421
Filing Date: 2004-04-20
Classification: F24D,F28D,Y02B,Y02E

Abstract:
In a plumbing system for a building, the plumbing system including a supply of a first cold water liquid and supply of a second liquid comprising drainwater, the improvement comprising an apparatus to transfer heat between said second liquid and said first liquid, said apparatus comprising at least one reservoir;a third liquid substantially filling said at least one reservoir; at least one first heat exchanger for said first liquid in thermal communication with at least a portion of said third liquid; at least one second heat exchanger passing through the interior of said reservoir for said second liquid, said at least one second heat exchanger comprising tube means having at least one central portion and at least two end portions; said at least one central portion having an exterior surface for heat transfer and at least one of said two end portions extending from said at least one reservoir for connection to said supply supply of drainwater; at least one convection chamber means enclosing at least a substantial portion of said central portion of said second heat exchanger; said at least one convection chamber means holding a fourth liquid comprising a relatively small volume of said third liquid; said at least one convection chamber means having an exterior wall of thermal insulating material; said fourth liquid submerging at least a substantial portion of said exterior surface of said at least one second heat exchanger; said at least one convection chamber means having at least one unobstructed opening into said reservoir for convective heat transfer between said fourth liquid and said third liquid; the arrangement being such that substantially all heat transfer with said second liquid takes place due to the resultant change in density of said fourth liquid, and that said third and first liquids are substantially only heated when said at least one unobstructed opening in said at least one convection chamber means is facing only upwardly, and that said third and first liquids are substantially only cooled when said at least one unobstructed opening in said at least one convection chamber means is facing only downwardly.