scope:

This Standard covers the construction and performance* (see Clause 3, Definitions) of gas-fired appliances with inputs up to and including 400 000 Btu/h (117.23 kW)† to determine their suitability for use at high altitude. The appliances include furnaces, boilers, room heaters, unit heaters, water heaters, and such other appliances where field conditions indicate the necessity of testing for high altitude use (see Clause 3, Definitions). The test rate means the appliance's input at a datum of 600 ft (152 m) or 29.38 in Hg (99.2 kPa) pressure.

* At the option of the manufacturer, tests specified in Clause 5, Performance, may be conducted at a high-altitude location.

† This input limitation reflects what is currently required by inspection authorities in high-altitude areas (i.e., appliances under 400 000 Btu/h (117.23 kW) must meet the requirements of this Standard). Appliances with inputs in excess of 400 000 Btu/h (117.23 kW) may still be reviewed for compliance with this Standard.

This Standard applies to appliances specified in Clause 1.1 when for use over an altitude range of 2000 to 4500 ft (610 to 1370 m), or 0 to 4500 ft (0 to 1370 m).

In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (nonmandatory) to define their application.