Flue Exhaust Fan with Configurable Outlet

Abstract

A flue exhaust fan has a configurable upwardly facing outlet for delivery of a mixture of gas and ambient air from the water heater or a furnace into either a vertical flue or a horizontal flue. Because the horizontal flue necessarily includes a 90° transition between the upwardly facing outlet and the horizontal flue, the horizontal flue has a greater flow resistance than the vertical flue. By installing a straight connector with a flow resistance element, the gas flow resistance encountered by the flue exhaust fan is the same for a vertical flue and a horizontal flue therefore requiring a single flue exhaust fan with a flow rating for installation with a horizontal flue or a vertical flue.

I claim: 
     
         1 . A flue exhaust fan with a rated gas flow for connection to a flue comprising:
 a. a fan housing;   b. an upwardly facing outlet from the fan housing, the upwardly facing outlet configured to connect compatibly to:
 i. an angled connector with an angled connector inlet for connecting the upwardly facing outlet to a horizontal flue, the angled connector having a first gas flow resistance; or 
 ii. a straight connector with a straight connector inlet for connecting the upwardly facing outlet to a vertical flue, the straight connector including a resistance element to produce a second gas flow resistance for the straight connector, 
   
       wherein the rated gas flow of the flue exhaust fan matches the first gas flow resistance of the angled connector and matches the second gas flow resistance of the straight connector. 
     
     
         2 . The flue exhaust fan of  claim 1 , wherein the resistance element is located inside the straight connector and has a resistance element inlet, a resistance element outlet, and resistance element wall connecting the resistance element inlet and resistance element outlet and wherein the cross-sectional area of the resistance element inlet is greater than or equal to the cross-section area of the resistance element outlet. 
     
     
         3 . The flue exhaust fan of  claim 2 , wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between the straight connector inlet of the straight connector and wherein the annular groove is connected to a drain tube for draining condensate out of the straight connector. 
     
     
         4 . The flue exhaust fan of  claim 3 , wherein the straight connector has a straight connector wall and the resistance element is located inside the straight connector and offset from the straight connector wall so that condensate can flow along the straight connector wall and into the annular groove. 
     
     
         5 . The flue exhaust fan of  claim 4 , wherein the resistance element wall flares outwardly toward the resistance element inlet to align with the annular groove so that condensate on the resistance element wall drips into the annular groove. 
     
     
         6 . The flue exhaust fan of  claim 1 , wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between an angled connector inlet of the angled connector and wherein the annular groove is connected to a drain tube for draining condensate out of the angled connector. 
     
     
         7 . A flue exhaust fan for connection to a flue comprising:
 a. a fan housing;   b. an upwardly facing outlet from the fan housing, the upwardly facing outlet configured to connect compatibly to a flue connector, wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between the upwardly facing outlet and the flu connector and wherein the annular groove is connected to a drain tube for draining condensate out of the flue connector.   
     
     
         8 . A straight connector for connecting an upwardly facing fan outlet of a flue exhaust fan to a flue, the straight connector comprising:
 a. a straight connector inlet, a straight connector outlet, and a straight connector wall forming an enclosed straight connector passage through the straight connector between the straight connector inlet and the straight connector outlet;   b. a resistance element located inside the straight connector passage and having a resistance element inlet with a resistance element inlet cross-sectional area, and resistance element outlet with a resistance element outlet cross-sectional area, and a resistance element wall connecting the resistance element inlet and the resistance element outlet.   
     
     
         9 . The straight connector of  claim 8 , wherein the resistance element inlet cross-sectional area is greater than or equal to the resistance element outlet cross-sectional area. 
     
     
         10 . The straight connector of  claim 8 , wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between the straight connector inlet of the straight connector and wherein the annular groove is connected to a drain tube for draining condensate out of the straight connector. 
     
     
         11 . The straight connector of  claim 10 , wherein the resistance element of the straight connector is offset from the resistance element wall so that condensate can flow along the resistance element wall and into the annular groove. 
     
     
         12 . The straight connector of  claim 11 , wherein the resistance element wall flares outwardly toward the resistance element inlet to align with the annular groove so that condensate on the resistance element wall drips into the annular groove.