18-28-927 Recirculating Direct Gas-Fired Industrial Air Heaters.

18-28-927.1 Application.

   Direct gas-fired industrial air heaters of the recirculating type shall be listed in accordance ANSI Z 83.18, Recirculating Direct Gas-Fired industrial Air Heaters.

18-28-927.2 Prohibited installations.

18-28-927.2.1

   Recirculating direct gas-fired industrial air heaters shall not serve any area containing sleeping quarters.

18-28-927.2.2

   Recirculating direct gas-fired industrial air heaters shall not recirculate room air in buildings that contain flammable solids, liquids. or gases. explosive materials, or substances that can become toxic when exposed to flame or heat.

18-28-927.3 Installation.

   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.

18-28-927.4 Clearance from combustible materials.

   Recirculating direct gas-fired industrial air heaters shall be installed with a clearance from combustible materials of not less than that shown on the rating plate and the manufacturer's instructions.

18-28-927.5 Air supply.

   Ventilation air to the recirculating direct gas-fired industrial air heater shall be ducted directly from outdoors. Air to the recirculating direct gas-fired industrial air heater in excess of the minimum ventilation air specified on the heater's rating plate shall be taken from the building, ducted directly from outdoors, or a combination of both. Where outside air dampers or closing louvers are used, they shall be verified to be in the open position prior to main burner operation.

18-28-927.6 Atmospheric vents, gas reliefs, or bleeds.

   Recirculating direct gas-fired industrial air heaters with valve train components equipped with atmospheric, vents, gas reliefs, or bleeds shall have their vent lines, gas reliefs, or bleeds lead to a safe point outdoors. Means shall be employed on these lines to prevent water from entering and to prevent blockage from insects and foreign matter. An atmospheric vent line shall not be required to be provided on a valve train component equipped with a listed vent limiter.