Low nox burner for a water heater

Abstract

A low NOx burner includes an upper plate and a lower plate joined together. A chamber is defined between an upper inner portion and a lower inner portion. The peaks of upper and lower scalloped ridges are in contact such that multiple ports are defined. The ports extend radially outward from the chamber. The chamber is adapted to receive a fuel/air mixture through a fuel/air intake opening. The ports permit a flow of the fuel/air mixture from the chamber for combustion to create a diffuse flame. An intermediate portion is positioned such that the flame attaches to the intermediate portion. The intermediate portion and a trough are arranged such that flame is directed downwards to the trough from the intermediate portion and attaches to the trough. An outer rim is positioned and angled to attach the flame to the trough and to direct the flame upwards from the trough.

1 . A low NOx burner comprising:
 an upper plate defining an upper plate axis and including an inner upper portion, an upper scalloped ridge surrounding the upper inner portion, and a lip surrounding the upper scalloped ridge, the upper inner portion extending radially outward a first radial distance from the upper plate axis to the upper scalloped ridge, the upper scalloped ridge defining peaks and valleys and having an upper portion, and the lip angling radially outward and downward from the upper portion of the upper scalloped ridge and defining an outer circumferential edge of the upper plate; and   a lower plate defining a lower plate axis and including a lower inner portion, a lower scalloped ridge surrounding the lower inner portion, an exit portion surrounding the lower scalloped ridge, an intermediate portion surrounding the exit portion, a trough surrounding the intermediate portion, and an outer rim surrounding the trough, the inner portion having a fuel/air intake opening and extending radially outward the first radial distance from the lower plate axis to the lower scalloped ridge, the lower scalloped ridge defining peaks and valleys and having a lower portion, the exit portion angling radially outward and downward from the lower portion of the lower scalloped ridge, the intermediate portion extending from the exit portion to a distal end at a second radial distance, the second radial distance greater than the first radial distance, the trough being below and radially outward of the intermediate portion, the outer rim including an outer circumferential edge of the lower plate;   wherein the upper scalloped ridge and the lower scalloped ridge are joined together so that the upper plate axis and the lower plate axis are collinear, such that a chamber is defined between the upper inner portion and the lower inner portion, such that the peaks of the upper and lower scalloped ridges are in contact, and such that a plurality of ports are defined between the valleys of the upper and lower scalloped ridges, the ports extending radially outward from the chamber through the scalloped ridges;   wherein the chamber is adapted to receive a fuel/air mixture through the fuel/air intake opening;   wherein the ports are adapted to permit a flow of the fuel/air mixture from the chamber for combustion to create a diffuse flame;   wherein the intermediate portion is positioned such that the flame attaches to the intermediate portion;   wherein the intermediate portion and trough are arranged such that flame is directed downwards to the trough from the intermediate portion and attaches to the trough; and   wherein the outer rim is positioned and angled to attach the flame to the trough and to direct the flame upwards from the trough.   
     
     
         2 . The low NOx burner of  claim 1 , wherein the intermediate portion defines a horizontal plane;
 wherein the entire trough is located below the horizontal plane;   wherein the trough is angled downwards with respect to the horizontal plane; and   wherein a trough angle is defined between the horizontal plane and the trough.   
     
     
         3 . The low NOx burner of  claim 2 , wherein a rim angle is defined between the outer rim and the horizontal plane; and
 wherein the rim angle is greater than the trough angle.   
     
     
         4 . The low NOx burner of  claim 2  further comprising:
 a plurality of first air apertures in the lower plate, the first air apertures located radially outward from the ports; and 
 a plurality of second air apertures in the lower plate, the second air apertures located radially outward from the first air apertures; 
 wherein the first air apertures and the second air apertures are positioned near the ports to introduce secondary air to help to complete combustion of the fuel/air mixture. 
 
     
     
         5 . The low NOx burner of  claim 4  further comprising:
 a plurality of third air apertures in the lower plate, the third air apertures located radially outward from the second air apertures; 
 wherein the third air apertures are positioned to introduce secondary air near the trough to help complete combustion of the fuel/air mixture. 
 
     
     
         6 . The low NOx burner of  claim 5 , wherein the third air apertures are in the trough. 
     
     
         7 . The low NOx burner of  claim 6 , wherein the first air apertures are formed as slots, the second air apertures are formed as slots, and the third air apertures are formed as slots. 
     
     
         8 . The low NOx burner of  claim 6 , wherein the first air apertures are formed as circular holes, the second air apertures are formed as circular holes, and the third air apertures are formed as circular holes. 
     
     
         9 . The low NOx burner of  claim 2  further comprising:
 a plurality of air apertures in the trough; 
 wherein the air apertures are positioned to introduce secondary air near the trough to help to complete combustion of the fuel/air mixture. 
 
     
     
         10 . The low NOx burner of  claim 1  further comprising:
 a plurality of first air apertures in the lower plate, the first air apertures located radially outward from the ports; and 
 a plurality of second air apertures in the lower plate, the second air apertures located radially outward from the first air apertures; 
 wherein the first air apertures and the second air apertures are positioned near the ports to introduce secondary air to help to complete combustion of the fuel/air mixture. 
 
     
     
         11 . The low NOx burner of  claim 10  further comprising:
 a plurality of third air apertures in the lower plate, the third air apertures located radially outward from the second air apertures; 
 wherein the third air apertures are positioned to introduce secondary air near the trough to help complete combustion of the fuel/air mixture. 
 
     
     
         12 . The low NOx burner of  claim 11 , wherein the third air apertures are in the trough. 
     
     
         13 . The low NOx burner of  claim 1  further comprising:
 a plurality of air apertures in the trough; 
 wherein the air apertures are positioned to introduce secondary air near the trough to help complete combustion of the fuel/air mixture. 
 
     
     
         14 . A low NOx burner comprising:
 an upper plate defining an upper plate axis and including an inner upper portion, an upper scalloped ridge surrounding the upper inner portion, and a lip surrounding the upper scalloped ridge, the upper inner portion extending radially outward a first radial distance from the upper plate axis to the upper scalloped ridge, the upper scalloped ridge defining peaks and valleys and having an upper portion, and the lip angling radially outward and downward from the upper portion of the upper scalloped ridge and defining an outer circumferential edge of the upper plate; and   a lower plate defining a lower plate axis and including a lower inner portion, a lower scalloped ridge surrounding the lower inner portion, an exit portion surrounding the lower scalloped ridge, an intermediate portion surrounding the exit portion and an outer rim surrounding the intermediate portion, the inner portion having a fuel/air intake opening and extending radially outward the first radial distance from the lower plate axis to the lower scalloped ridge, the lower scalloped ridge defining peaks and valleys and having a lower portion, the exit portion angling radially outward and downward from the lower portion of the lower scalloped ridge, the intermediate portion extending from the exit portion to a distal end at a second radial distance, the second radial distance greater than the first radial distance, the outer rim including the an outer circumferential edge of the lower plate;   wherein the upper scalloped ridge and the lower scalloped ridge are joined together so that the upper plate axis and the lower plate axis are collinear, such that a chamber is defined between the upper inner portion and the lower inner portion, such that the peaks of the upper and lower scalloped ridges are in contact, and such that a plurality of ports are defined between the valleys of the upper and lower scalloped ridges, the ports extending radially outward from the chamber through the scalloped ridges;   wherein the chamber is adapted to receive a fuel/air mixture through the fuel/air intake opening;   wherein the ports are adapted to permit a flow of the fuel/air mixture from the chamber for combustion to create a diffuse flame;   wherein the intermediate portion is positioned such that the flame attaches to the intermediate portion; and   wherein the outer rim is positioned and angled to attach the flame to the lower plate and to direct the flame upwards from the lower plate.   
     
     
         15 . The low NOx burner of  claim 14  further comprising:
 a plurality of first air apertures in the lower plate, the first air apertures located radially outward from the ports; and 
 a plurality of second air apertures in the lower plate, the second air apertures located radially outward from the first air apertures; 
 wherein the first air apertures and the second air apertures are positioned near the ports to introduce secondary air to help to complete combustion of the fuel/air mixture. 
 
     
     
         16 . A method of operating a low NOx burner, the method comprising the steps of:
 providing a low NOx burner including an upper plate having an outer diameter and a lower plate having an outer rim and an outer diameter, the plates joined together to define a chamber and a plurality of ports formed between the plates, the ports extending radially outward from the chamber, and the outer diameter of the upper plate being less than the outer diameter of the lower plate;   providing a fuel/air mixture to the chamber;   directing the fuel/air mixture through the ports;   combusting the fuel/air mixture to create a flame; and   directing the flame upwards at the outer rim to attach the flame to the lower plate.   
     
     
         17 . The method of  claim 16 , further comprising:
 directing the flame from the ports to a first elevation on the lower plate below the ports to attach the flame to the lower plate at the first elevation; and   directing the flame from the first elevation to a second elevation on the lower plate below the first elevation to attach the flame to the lower plate at the second elevation.   
     
     
         18 . The method of  claim 17 , the method further comprising:
 providing a first portion of secondary air to the flame at a first distance radially outward from the ports; and   providing a second portion of secondary air to the flame at a second distance radially outward from the ports, the second distance greater than the first distance.   
     
     
         19 . The method of  claim 18 , the method further comprising:
 providing a third portion of secondary air to the flame at a third distance radially outward from the ports, the third distance greater than the second distance;   providing the third portion of secondary air at the second elevation.   
     
     
         20 . The method of  claim 17 , the method further comprising:
 providing secondary air to the flame radially outward from the ports at the second elevation.