Figure 18. Gas-fired infrared tube-type heater needs to be replaced or removed. Photo from Gladstein, Neandross & Associates, NREL 44903 Figure 21. Gas-fired fan heater needs to be replaced or removed. Photo from Gladstein, Neandross & Associates , NREL 44696 Figure 19. Electric infrared radiant heater needs to be replaced or removed. Photo from Gladstein, Neandross & Associates, NREL 44904 instance, modifying the heating system to be compliant with the codes would only require replacing the heater(s). However, it is essential that the supply air and exhaust flow from these heater(s) be completely contained and directed from and to the outside of the facility.
This can be accomplished by routing the inlet air and exhaust air through the facility wall or roof. Portable propane heaters (Figure 20) are prohibited from use within a CNG vehicle maintenance facility. Gas-fired fan-type heaters (Figure 21) are not compliant because of their inherent open flame(s) and must be replaced with units that meet the codes. This includes gas-fired fan-type heaters in which the only open flame is the pilot light. Although forced air heating systems do not present direct hazards as potential ignition sources for combustible gas, modifications may be required to their air flow systems because of their potential effect on the paths of migra tion.
However, such continuous ventilation will extract warmed air from the building, and such single-pass heating may be cost prohibitive, particularly in colder climates. To address this heat loss, many owners utilize units with heat recovery. Ducted heating units should be designed to provide air flow prior to igniting a burner. Figure 20. Floor-mounted portable propane heater should be eliminated. Photo from Gladstein, Neandross & Associates, NREL 44905 Compliance with the codes and regulations can be achieved by simply removing the non-compliant heating units and/or replacing them with units that are considered compliant.
Gas-fired infrared tube-type radiant heaters (Figure 18) are commonly employed in maintenance facilities that service conventionally fueled vehicles. Manufacturers of these types of heating systems now produce units that have contained flames and surface elements that do not exceed 750°F. In this Electrical Wiring, Lighting, and Appliance Considerations Electrical wiring, lighting, and electrical appliances all present potential ignition sources within a maintenance facility. A spark that is caused by an abnormal condition such as a short circuit within a wire conduit or junction COMPRESSED NATURAL GAS VEHICLE MAINTENANCE FACILITY MODIFICATION HANDBOOK 16