Water Heater and a Method of Operating Same

Abstract

A water heater (10) including a tank (12), a burner (26) and a heated gas outlet duct (40). The tank (12) has a substantially central flue (14) having an outlet (24) substantially adjacent the top (20) of the tank (12). The tank (12) is adapted for mounting with the flue (14) substantially vertically. The burner (26) is located beneath the tank (12). The burner (26) has an air inlet (32) and a pilot flame and is adapted to a burn a fuel to discharge heated gases up through the flue (14). The heated gas outlet duct (40) is of substantially unrestricted cross-section and has an upper, first end (42) in gas communication with the flue outlet (24) and a second, lower end (46) in gas communication with atmosphere. When only the pilot flame is burning, the heated gas outlet duct (40) is adapted to restrict the air drawn into the flue (14) via the air inlet (32) to the minimum amount required to maintain the pilot flame alight.

1 . A water heater including: a tank with a substantially central flue having an outlet substantially adjacent the top of the tank, the tank being adapted for mounting with the flue substantially vertical; a burner located beneath the tank, the burner having an air inlet and a pilot flame and being adapted to a burn a fuel to discharge heated gases up through the flue; and a heated gas outlet duct of substantially unrestricted cross-section having an upper, first end in gas communication with the flue outlet and a second, lower end in gas communication with atmosphere,
 wherein, when only the pilot flame is burning, the heated gas outlet duct is adapted to restrict the air drawn into the flue via the air inlet to the minimum amount required to maintain the pilot flame alight.   
   
   
       2 . The water heater as claimed in  claim 2 , wherein the length of the duct is approximately 20% to 30% of the length of the flue. 
   
   
       3 . The water heater as claimed in  claim 1 , wherein the length of the duct is approximately 25% of the length of the flue. 
   
   
       4 . The water heater as claimed in  claim 1 , wherein the duct and the flue are cylindrical. 
   
   
       5 . The water heater as claimed in  claim 4 , wherein the duct and flue have approximately equal diameters. 
   
   
       6 . A water heater including: a tank with a substantially central flue having an outlet substantially adjacent the top of the tank, the tank being adapted for mounting with the flue substantially vertical; a burner located beneath the tank, the burner having an air inlet and an electronically controlled ignitor and being adapted to a burn a fuel to discharge heated gases up through the flue; and a heated gas outlet duct of substantially unrestricted cross-section having an upper, first end in gas communication with the flue outlet and a second, lower end in gas communication with atmosphere, wherein, the duct has approximately the same cross sectional area of the flue and is approximately 25% of the length of the flue. 
   
   
       7 . The water heater claimed in  claim 6 , wherein the duct and the flue are cylindrical. 
   
   
       8 . A method of maintaining a pilot flame alight in a water heater having a tank with: a bottom; a top; and a substantially central flue, the method including the steps of: directing the heated gases from the pilot flame from the tank bottom to the tank top via the flue; and directing the heated gases from the tank top to atmosphere via a generally downwardly directed duct of substantially unrestricted cross-section, the duct being adapted to restrict the gas flow drawn into the flue to only the minimum amount required to maintain the pilot flame alight. 
   
   
       9 . A method of operating a water heater in idle mode, the water heater having a tank with: a bottom; a top; a burner with a pilot flame; and a substantially central flue, the method including the steps of: directing the heated gases from the pilot flame from the tank bottom to the tank top via the flue; and directing the heated gases from the tank top to atmosphere via a generally downwardly directed duct of substantially unrestricted cross-section, the duct being adapted to restrict the gas flow drawn into the flue to only the minimum amount required to maintain the pilot flame alight.