Importance

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Abstract

A gas-fired construction heater which meets the applicable ANSI Standard and operates to supply heated air separately from products of combustion. The products of combustion are permitted to contain no more than a specified percent of carbon monoxide when uncontrolled heater operating conditions are within predetermined ranges. The uncontrolled operating conditions include variations in input rate and supply voltage. A combustion chamber produces the products of combustion and has primary and secondary combustion zones. A heat exchanger receives the products of combustion and transfers heat therefrom to fresh air to be heated. The chamber and the heat exchanger define a tertiary combustion zone. Inlets supply a separate natural combustion draft to each of the primary and tertiary combustion zones. The inlets include a first and a third fixed-area inlet for respectively supplying the separate natural drafts to the primary and tertiary combustion zones. An additional fixed-area inlet supplies forced draft and natural draft to the secondary combustion zone. The fixed-area of each of these inlets is selected so that the specified percent is not exceeded during operation of the heater when the uncontrolled variation of either the input rate or the supply voltage is within its respective predetermined range. When the uncontrolled variations are outside of the respective predetermined ranges, the heater is turned off.

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First Claim