Unit heaters, packaged heaters, and duct fumaces with burmers having input rates over 400,000 Btu/hr (117 228 W) shall comply with the fllowing when applicable:
a. Air inlet and exhaust damper and their operating means, shall be designed to provide stable and safe ignition and combustion for the entire range of burner operation.
b. Breakage or filure of the air inlet or exhaust damper or their operating means shall not result in an unsafe condition.
