Water tank heated by smoke from a furnace

Abstract

Apparatus interposed in a smoke flue between a furnace and a chimney for recovering energy from smoke and heating water therewith. A tank contains a volume of water to be heated. A water inlet and a water outlet supply cold water to the tank and discharge heated water. A plurality of heat exchanging tubes extends through the interior of the tank such that the ends communicate with opposite exterior surfaces of the tank or extend outwardly therefrom. A plurality of sleeves, one for each tube, has an outside diameter slightly less than the inside diameter of the tubes such that each sleeve is positioned within one of the tubes in concentric manner and sealed to the ends of the tube to define an annular air space there-between. Expanding and reducing elements provide gaseous communication between the flue and the plurality of sleeves. The sum of the cross-sectional areas of the plurality of sleeves equals or exceeds the cross-sectional area of the smoke flue such that normal convection of smoke within the flue is not restricted. The sleeves have a plurality of small apertures therethrough, thereby permitting limited gaseous communication with the annular air space for greater heat exchanging efficiency. A by-pass flue, first normally-open damper in the smoke flue between the expanding element and the by-pass flue and a second normally-closed damper in the by-pass flue change positions and divert smoke through the by-pass flue when the water in the tank is heated to a predetermined temperature.

Dependencies are inferred from the claim text.