Heat exchanger

Abstract

A heat exchanger for an appliance having a burner includes at least one tubular heat exchanger section extending from an inlet end aligned with the burner and an outlet end. The inlet end includes a first portion having a first inner diameter and a second portion having a second inner diameter greater than the first diameter.

What is claimed is: 
     
         1 . A heat exchanger for an appliance having a burner, comprising:
 at least one tubular heat exchanger section extending from an inlet end aligned with the burner and an outlet end, wherein the inlet end includes a first portion having a first inner diameter and a second portion having a second inner diameter greater than the first diameter.   
     
     
         2 . The heat exchanger recited in  claim 1 , wherein the second portion of the inlet end is positioned upstream of the first portion. 
     
     
         3 . The heat exchanger recited in  claim 2 , wherein the second portion defines an opening at the axial extent of the inlet end. 
     
     
         4 . The heat exchanger recited in  claim 1  further comprising an insulation sleeve positioned within the second portion and having an inner diameter substantially equal to the first diameter of the inlet end, the insulation sleeve helping to protect the inlet end from thermal damage. 
     
     
         5 . The heat exchanger recited in  claim 4 , wherein the at least one heat exchanger section comprises a plurality of heat exchanger sections, each including the second portion and an insulation sleeve provided therein. 
     
     
         6 . The heat exchanger recited in  claim 4 , wherein the insulation sleeve is tubular and includes a passage extending between first and second openings aligned with the first portion of the heat exchanger section. 
     
     
         7 . The heat exchanger recited in  claim 2 , wherein the insulation sleeve is ceramic. 
     
     
         8 . The heat exchanger recited in  claim 1 , wherein the inlet end has a swaged connection with a vestibule panel of the appliance. 
     
     
         9 . The heat exchanger recited in  claim 1 , wherein the inlet end and outlet end are positioned on the same side of the heat exchanger section. 
     
     
         10 . The heat exchanger recited in  claim 1 , wherein the inlet end and outlet end are positioned on opposite sides of the heat exchanger section. 
     
     
         11 . The heat exchanger recited in  claim 1 , wherein the inlet end receives a flame from a low NO x  burner. 
     
     
         12 . A furnace comprising:
 a burner including a distributor having at least one curved second portion for providing a flame;   a vestibule panel connected to the burner and including an opening aligned with each second portion downstream of the burner; and   a heat exchanger comprising at least one tubular heat exchanger section extending from an inlet end aligned with each second portion of the burner and an outlet end, wherein the inlet end includes a first portion having a first inner diameter and a second portion having a second inner diameter greater than the first diameter.   
     
     
         13 . The furnace recited in  claim 12  further comprising an insulation sleeve positioned within the second portion of the heat exchanger section and having an inner diameter substantially equal to the first diameter of the inlet end, the insulation sleeve helping to protect the inlet end from thermal damage. 
     
     
         14 . The furnace recited in  claim 12 , wherein the second portion of the inlet end is positioned upstream of the first portion. 
     
     
         15 . The furnace recited in  claim 12 , wherein the second portion defines an opening at the axial extent of the inlet end. 
     
     
         16 . The furnace recited in  claim 12  further comprising an insulation sleeve positioned within the second portion and having an inner diameter substantially equal to the first diameter of the inlet end, the insulation sleeve helping to protect the inlet end from thermal damage. 
     
     
         17 . The furnace recited in  claim 16 , wherein the at least one heat exchanger section comprises a plurality of heat exchanger sections, each including the second portion and an insulation sleeve provided therein. 
     
     
         18 . The furnace recited in  claim 16 , wherein the insulation sleeve is tubular and includes a passage extending between first and second openings aligned with the first portion of the heat exchanger section. 
     
     
         19 . The furnace recited in  claim 16 , wherein the insulation sleeve is ceramic. 
     
     
         20 . The furnace recited in  claim 16 , wherein the inlet end has a swaged connection with each opening in the vestibule panel. 
     
     
         21 . The furnace recited in  claim 12 , wherein the inlet end and outlet end are positioned on the same side of the heat exchanger section. 
     
     
         22 . The furnace recited in  claim 12 , wherein the inlet end and outlet end are positioned on opposite sides of the heat exchanger section. 
     
     
         23 . The furnace recited in  claim 12 , wherein the burner is a low NO x  burner. 
     
     
         24 . A heat exchanger for an appliance having a burner, comprising:
 a plurality of heat exchanger sections each extending from an inlet end aligned with the burner and an outlet end, the inlet and outlet ends being positioned on the same side of the heat exchanger section, wherein each inlet end includes a first portion having a first inner diameter and a second portion having a second inner diameter greater than the first diameter; and   a ceramic insulation sleeve positioned within the second portion of each heat exchanger section and having an inner diameter substantially equal to the first diameter of the inlet end, the insulation sleeve helping to protect the inlet end from thermal damage.