Preface

This publication represents a basic standard for safe operation, substantial and durable construction, and acceptable performance of a gas unit heater, gas packaged heater, gas utility heater, or gas-fired duct furnace. It is the result of years of experience in the manufacture, testing, installation, maintenance, inspection and research on a gas unit heater, gas packaged heater, gas utility heater, or gas-fired duct furnace designed for utilization of gas. There are risks of injury to persons inherent in appliances that, if completely eliminated, would defeat the utility of the appliance. The provisions in this standard are intended to help reduce such risks while retaining the normal operation of the appliance.

Scope

1.1.1
This standard applies to newly produced gas fired-duct furnaces, packaged heaters, utility heaters with inputs up to and including 400,000 Btu/hr (117 228 W), and unit heaters with input rates up to and including 10,000,000 Btu/hr (2 930 712 W) and constructed entirely of new, unused parts and materials:
a. For use with natural gas with inlet gas pressures up to and including 5.0 psi (34.5 kPa); unit heaters, packaged heaters, and duct furnaces with burners having input rates over 400,000 Btu/hr (117 228 W) may have higher inlet pressures;
b. For use with liquefied petroleum gases; and
c. Convertible for use with natural gas and liquefied petroleum gases, when provision is made for the conversion from one gas to the other.