Acoustic Shunt and Method of Attenuating Noise Generated in a Heater Venting System

Abstract

A heater venting system comprises an exhaust blower, an exhaust pipe, and an acoustic shunt. An exhaust passageway of the exhaust pipe is in fluid communication with the blower discharge. The acoustic shunt includes a pipe section having a shunt chamber of a shunt chamber length. The shunt is coupled to the exhaust pipe such that the shunt chamber is in fluid communication with the exhaust passageway such that the shunt chamber extends generally laterally from the exhaust passageway. The shunt chamber length is sized to attenuate the noise of the heater venting system.

1 . A method of attenuating noise generated in a heater venting system, the heater venting system comprising an exhaust blower and an exhaust pipe, the exhaust pipe at least in part defining an exhaust passageway, the method comprising:
 integrating a shunt in the heater venting system, the shunt including a pipe section having a shunt chamber, the shunt chamber having an open end, a closed end, and a shunt chamber length extending from the open end to the closed end, the shunt being coupled to the exhaust pipe such that the shunt chamber is in fluid communication with the exhaust passageway via the open end of the shunt chamber and such that the shunt chamber extends generally laterally from the exhaust passageway,   manually adjusting the shunt to a shunt chamber length that attenuates noise within the heater venting system;   the shunt being adapted such that the shunt chamber length remains unchanged until a user manually changes the shunt chamber length.   
     
     
         2 . A method as set forth in  claim 1  wherein the noise includes an objectionable tone, and wherein the step of manually adjusting the shunt comprises manually adjusting the shunt to a shunt chamber length which attenuates the objectionable tone by at least ten decibels. 
     
     
         3 . A method as set forth in  claim 2  wherein the shunt is adjusted such that the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and λ is the wavelength of the objectionable tone. 
     
     
         4 . A method as set forth in  claim 2  wherein the exhaust blower includes a fan having a plurality of fan blades, and a motor adapted for rotating the fan, and wherein the shunt is adjusted such that the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and λ=(S+V)/F, where S is the speed of sound in air, V is the air velocity in the exhaust passageway, and F is the fan blade pass frequency when the motor is rotating the fan at an operational speed. 
     
     
         5 . A method as set forth in  claim 1  wherein the noise includes an objectionable tone, and wherein the shunt is positioned in a manner such that the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and A is the wavelength of the objectionable tone. 
     
     
         6 . A method as set forth in  claim 1  wherein the exhaust blower includes a fan having a plurality of fan blades, and a motor adapted for rotating the fan, and wherein the shunt is positioned such that the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and λ=(S+V)/F, where S is the speed of sound in air, V is the air velocity in the exhaust passageway, and F is the fan blade pass frequency when the motor is rotating the fan at an operational speed. 
     
     
         7 . A method as set forth in  claim 1  wherein the integrating of the shunt includes positioning the shunt such that the closed end is above the open end to prevent liquid from collecting in the shunt. 
     
     
         8 . A method of attenuating noise generated in a heater venting system, the heater venting system comprising an exhaust blower and an exhaust pipe, the exhaust pipe at least in part defining an exhaust passageway, the method comprising:
 integrating a first shunt in the heater venting system, the first shunt including a pipe section having a shunt chamber, the shunt chamber of the first shunt having an open end, a closed end, and a shunt chamber length extending from the open end to the closed end, the first shunt being coupled to the exhaust pipe such that the shunt chamber of the first shunt is in fluid communication with the exhaust passageway via the open end of the shunt chamber and such that the shunt chamber of the first shunt extends generally laterally from the exhaust passageway,   integrating a second shunt in the heater venting system, the second shunt including a pipe section having a shunt chamber, the shunt chamber of the second shunt having an open end, a closed end, and a shunt chamber length extending from the open end to the closed end of the second shunt, the second shunt being coupled to the exhaust pipe such that the shunt chamber of the second shunt is in fluid communication with the exhaust passageway via the open end of the shunt chamber of the second shunt and such that the shunt chamber of the second shunt extends generally laterally from the exhaust passageway, the shunt chamber length of the first shunt being of a first length to attenuate a first noise of a first frequency, the shunt chamber length of the second shunt being of a second length to attenuate a second noise of a second frequency, the second length being different from the first length, the second frequency being different from the first frequency.   
     
     
         9 . A method of attenuating noise generated in a heater venting system, the heater venting system comprising an exhaust blower and an exhaust pipe, the exhaust pipe at least in part defining an exhaust passageway, the method comprising inducing a user to:
 integrate a shunt in the heater venting system, the shunt including a pipe section having a shunt chamber, the shunt chamber having an open end, a closed end, and a shunt chamber length extending from the open end to the closed end, the shunt being coupled to the exhaust pipe such that the shunt chamber is in fluid communication with the exhaust passageway via the open end of the shunt chamber and such that the shunt chamber extends generally laterally from the exhaust passageway,   manually adjusting the shunt to a the shunt chamber length which attenuates noise within the heater venting system, the shunt being adapted such that the shunt chamber length remains unchanged until a user manually changes the shunt chamber length.   
     
     
         10 . A method as set forth in  claim 9  wherein the step of inducing a user to integrate a shunt in the heater venting system comprises providing instructions sufficient to cause the user to integrate the shunt in the heater venting system. 
     
     
         11 . A heater venting system comprising:
 an exhaust blower having a blower discharge;   and an exhaust pipe, the exhaust pipe at least in part defining an exhaust passageway, the exhaust passageway being in fluid communication with the blower discharge;   an acoustic shunt including a pipe section having a shunt chamber, the shunt chamber having an open end, a closed end, and a shunt chamber length extending from the open end to the closed end, the shunt having a threaded tubular portion and a threaded plug sized and configured to threadably mate with the tubular portion, the shunt being adapted such that the shunt chamber length may be adjusted by turning the plug relative to the tubular portion, the shunt being coupled to the exhaust pipe such that the shunt chamber is in fluid communication with the exhaust passageway via the open end of the shunt chamber and such that the shunt chamber extends generally laterally from the exhaust passageway, the shunt chamber length being sized to attenuate the noise of the heater venting system.   
     
     
         12 . A heater venting system as set forth in  claim 11  wherein the noise includes an objectionable tone, and wherein the shunt is adapted and configured to attenuate the objectionable tone by at least ten decibels. 
     
     
         13 . A heater venting system as set forth in  claim 12  wherein the shunt is adapted and configured to facilitate changing of the shunt chamber length. 
     
     
         14 . A heater venting system as set forth in  claim 13  wherein the noise comprises an objectionable tone, and wherein the shunt is adjustable to a position in which the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and A is the wavelength of the objectionable tone. 
     
     
         15 . A heater venting system as set forth in  claim 13  wherein the exhaust blower includes a fan having a plurality of fan blades, and a motor adapted for rotating the fan, the shunt being adjustable to a position in which the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and λ=(S+V)/F, where S is the speed of sound in air, V is the air velocity in the exhaust passageway, and F is the fan blade pass frequency when the motor is rotating the fan at an operational speed. 
     
     
         16 . A heater venting system as set forth in  claim 12  wherein the noise includes an objectionable tone, and wherein the shunt is positioned in a manner such that the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and λ is the wavelength of the objectionable tone. 
     
     
         17 . A heater venting system as set forth in  claim 12  wherein the exhaust blower includes a fan having a plurality of fan blades, and a motor adapted for rotating the fan, the shunt being positioned such that the shunt chamber length is nλ/4±0.1(λ/4), where n is any odd integer and λ=(S+V)/F, where S is the speed of sound in air, V is the air velocity in the exhaust passageway, and F is the fan blade pass frequency when the motor is rotating the fan at an operational speed. 
     
     
         18 . A heater venting system as set forth in  claim 12  wherein the shunt is oriented such that the closed end is above the open end to prevent liquid from collecting in the shunt. 
     
     
         19 . A heater venting system as set forth in  claim 12  wherein the shunt comprises a first shunt, the heater venting system further comprising a second shunt, the second shunt including a pipe section having a shunt chamber, the shunt chamber of the second shunt having an open end, a closed end, and a shunt chamber length extending from the open end to the closed end of the second shunt, the second shunt being coupled to the exhaust pipe such that the shunt chamber of the second shunt is in fluid communication with the exhaust passageway via the open end of the shunt chamber of the second shunt and such that the shunt chamber of the second shunt extends generally laterally from the exhaust passageway, the shunt chamber length of the first shunt being of a first length to attenuate a noise of a first frequency, the shunt chamber length of the second shunt being of a second length to attenuate a noise of a second frequency, the second length being different from the first length, the second frequency being different from the first frequency. 
     
     
         20 . A heater venting system as set forth in  claim 12  wherein the shunt length is less than ten inches. 
     
     
         21 . A method as set forth in  claim 8  wherein the first noise includes an objectionable tone, the chamber length of the first shunt being nλ/4±0.1(λ/4), and the chamber length of the second shunt being nλ/8±0.1(λ/8), where n is any odd integer and λ is the wavelength of the objectionable tone.