scope:

This standard applies to newly produced gas fired-duct furnaces and unit heaters with input rates up to and including 10,000,000 Btu/h (2 931 KW) 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);

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.

The term "appliance" when used herein, applies to both gas-fired duct furnaces and unit heaters (See Part IV Definitions).

The construction of appliances for use with the above-mentioned gases is covered under Part I.

The performance of appliances for use with the above-mentioned gases is covered under Part II.

This Standard applies to Category I, Category II, Category III and Category IV Appliances. (See Part IV Definitions.)

This standard covers self-contained, automatically controlled, vented unit heaters and duct furnaces. These appliances are intended for installation in locations where flammable gases or vapors are not generally present. Unit heaters shall have an integral means for circulation of air, either propeller fans or blowers. These unit heaters, unless for outdoor installation are intended for installation in the space being heated. The unit heater may be either suspended or floor-mounted and of either the low- or high-static pressure type as defined in Part IV, Definitions.

These appliances are suitable for use in aircraft hangars, parking structures and repair garages when marked and installed, as applicable, in accordance with:

Standard on Aircraft Hangars, ANSI/NFPA 409

Standard for Parking Structures, ANSI/NFPA 88A

Standard for Repair Garages, ANSI/NFPA 888

Installation Code for Natural Gas and Propane Installation Code, CSA B149.1

This standard also applies to appliances with draft hoods which are factory equipped with automatic vent damper devices (see Part IV, Definitions), hereinafter referred to as vent damper devices.

A separated combustion system appliance anticipated by this standard is essentially a balanced flue appliance with the air intake and vent outlet in close proximity. Other designs shall be subjected to such additional tests as believed necessary at the discretion of the testing agency.

Exhibit G contains a list of standards specifically referenced in this standard, and sources from which these referenced standards may be obtained.

If a value for measurement as given in this standard is followed by an equivalent value in other units, the first stated value is to be regarded as the specification. (See Appendix E for Temperature Scales and Conversions).

Special construction provisions applicable to an appliance designed for use with an optional listed gas conversion kit are outlined under Exhibit C [(Optional) Provisions for Listed Appliance Gas Conversion Kits].

This standard also applies to newly produced automatic intermittent-pilot ignition systems (See Part IV Definitions), constructed entirely of new, unused parts and materials, to be adapted in the field to a unit heater or duct furnace equipped with an existing continuous pilot burner and which has been examined and tested for compliance with this standard when installed on the appliance. [See Exhibit D, (Optional) Provisions for Listed Appliance Ignition Conversion Kits].

All references to psi (kPa) throughout this Standard are to be considered "gauge" pressures unless otherwise specified.