Abstract: A method and apparatus for combusting a fuel and air mixture within a combustion chamber, particularly a combustion chamber of a gaseous fuel fired water heater. A pressure relief void is intentionally formed so that a combustion chamber forms communication with a surrounding environment through means other than the exhaust flue and/or a fuel and/or air inlet. During ignition, the pressure relief void allows pre-combustion fluid within the combustion chamber to escape through both the pressure relief void and the exhaust flue. The pressure relief void reduces or eliminates undesirable noise associated with start-up and operation of conventional water heater combustion chambers with premixed burner systems. The pressure relief void of this invention is preferably sized large enough to relieve an ignition pressure pulse from the combustion chamber upon ignition and yet is sized small enough to prevent a combustion flame from passing through the pressure relief void during ignition and/or operational combustion.

Abstract: An apparatus and method for operating a pilot burner apparatus and a main burner apparatus of a gas-fired appliance. The pilot burner apparatus draws combustion air from a first environment. The main combustion apparatus draws air from a second environment. In a shutdown condition, such as when a flammable vapor source is accidentally exposed to the second environment, the pilot burner apparatus draws air containing an undesired flammable vapor which eliminates the pilot flame, triggering a gas valve to close and shut down the fuel gas supply to the main burner apparatus and the pilot burner apparatus.

Abstract: A water heater including a water tank, a combustion chamber beneath the tank, a gas burner in the combustion chamber, an air plenum upstream of the combustion chamber, a flame arrestor located such that air in the air plenum passes through the flame arrestor to reach the combustion chamber, and a flue extending upwardly from the combustion chamber and through the water tank.

Abstract: A package boiler having water cooled surfaces positioned relatively close to the combustion burner to improve the radiant heat transfer. Extended surfaces are added to the water cooled tube fireside surface to increase absorption rates to the limits established by water side conditions to avoid departure from nucleate boiling (DNB). The heat release rates of multiple firing rate zone burners are matched to the absorption rates of the water cooled surfaces by adjusting the size and extent of the various firing rate zones. The burner is extended or the physical shape is altered to expose a larger surface to greater areas of water cooled furnace surface. The burner is matched to cooling surface to lower combustion zone temperatures and thus thermal NO.sub.X formations. Further, recirculated flue gas, excess air, water vapor or a combination of these may be used to add mass to the fluid stream flowing through the burner. Finally, either the gas fuel or combustion air may be staged.