scope:

This Standard covers the construction, and performance*, (See Part 111, DEFINITIONS) for gas-fired appliances with inputs up to and including 400 OOO Btuh (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 highaltitude use (See Part 111, DEFINITIONS). The test rate shall mean the appliance's input at a datum of 500 feet (152 m) or 29.38 inches of mercury (99.2 kPa) pressure.

* NOTE: At the option of the manufacturer, tests specified in Part I1 may be conducted at a high-altitude location.

** NOTE: This input limitation reflects what is currently required by inspection authorities in high-altitude areas (i.e. appliances under 400 000 Btuh must meet the requirements of this Standard). Appliances with inputs in excess of 400 000 Btuh may still be reviewed for compliance with this Standard.

This Standard applies to appliances specified in 1.1.1 when for use over an altitude range of 2 000 - 4 600 feet (610 - 1 370 m), or 0 - 4 500 feet (0 - 1 370 m).