This standard applies to newly produced, direct gas-fired process air heaters of the recirculating ornon-recirculating type, (5ee Definition), hereinafter referred to as heaters, whose primary purpose is toprovide process heating to non-occupied spaces within commercial and industrial buildings and may alsoincude operation as a non-recirculating ventilation air heater, (See Definition) if the heater is operatedduring periods when the space is occupied.
