Installation of direct gas-fired industrial air heaters shall comply with the following requirements:
1. Recirculating direct gas-fired industrial air heaters shall be installed in accordance with the manufacturer's instructions.
2. Recirculating direct gas-fired industrial air heaters shall be installed only in industrial or commercial occupancies.
3. Recirculating direct gas-fired industrial air heaters shall be permitted to provide fresh air ventilation only for the amount that exceeds the minimum ventilation air specified on the heater's rating plate to maintain the combustion level created by the heater in the space being served by the heater below 25 ppm for carbon monoxide, 3 ppm for nitrogen dioxide, and 5000 ppm for carbon dioxide. Where gas-powered fork trucks or other fossil fueled equipment are utilized in the conditioned space, additional ventilation requirements for the facility must be addressed separately.
4. Recirculating direct gas-fired industrial air heaters shall be provided with access for removal of burners; replacement of motors, controls, filters, and other working parts; and for adjustment and lubrication of parts requiring maintenance.