This PDF includes GI #2.
1.1.1 These requirements apply to door air heaters direct fired with natural gas, propane-air mixtures. The word gas is used to designate these as gaseous fuels and propane is used only where specific reference is made to fuel/air ratio.
1.1.2 These requirements apply to direct gas-fired door air heaters used to heat air where all of the heat and the products of combustion, generated by the gas burning device are released into the air stream.
1.1.3 These requirements apply to direct gas-fired door air heaters provided with automatic control devices and interlocks.
1.1.4 These requirements apply to direct gas-fired door air heaters designed and applied solely to provide a warm air barrier or curtain at a door opening directly to the out-of-doors.
1.1.5 These requirements apply to direct gas-fired nonrecirculating door air heaters with maximum rated inputs not exceeding 10 000 000 Btuh.
18.104.22.168 Heaters having maximum rated inputs greater than 10 000 000 Btuh which incorporate additional safety features may be investigated to the intent of these requirements. When installed as a combination door air heater and direct gas fired make-up air heater, DIRECT GAS-FIRED NON-RECIRCULATING MAKE-UP AIR HEATERS also apply.
1.1.6 Combination direct gas-fired non-recirculating make-up and door air heaters may be used in dual function as a direct make-up and door air heater if designed and applied in accordance with and conforming to these specifications and with the current standard CAN1-3.7 DIRECT GAS-FIRED NON-RECIRCULATING MAKE-UP AIR HEATERS.
1.1.7 A non-recirculating door air heater which complies with these requirements shall not be acceptable if it has features which impair the results contemplated by these requirements.
1.1.8 The gas burner and combustion system shall be of the modulating type. The minimum rate shall be no greater than that calculated by the following relationship:
Minimum Btuh = 6.0 Maximum Btuh/Design Temperature rise
The turndown range need not exceed 20:1.