ANSI Z91.1

Description / Abstract: This standard applies only to oil-powered forced-air central furnaces equipped with pressure-atomizing oil burners ¹ and does not apply to floor furnaces. It covers those furnaces having a specified input rating of 420000 Btu/h (British thermal units per hour) or less. Furnaces of this input or less comprise practically all of the domestic and light commercial market. It describes the test apparatus and procedures for determining the furnace rating of central furnaces at an air temperature rise of 85°F, and optional furnace ratings at other specified values of air temperature rise through the furnace.

¹Commercial Standard Warm-Air Furnace-Burner Units Equipped with Pressure-Atomizing or Rotary-Type Oil Burners, CS 195-60 (Washington, D. c.: Government Printing Office, 1960), which this standard supersedes, gave requirements for rotary-type oil burners and gravity-air furnaces. While these older type designs are still in operation, the market for new rotary-type oil burners and gravity furnaces in applications below a 420 OOO-Btu/h input is no longer significant.