upstream of the gas supply connection to the appliance.
COMBUSTION AIR REQUIREMENTS
Provide for adequate combustion and ventilation air in accordance with Sections 8.3, Air for Combustion and Ventilation, of the National Fuel Gas Code, ANSI Z223.1, or Sections 7.2, 7.3, 7.4 of CAN/CGA B149 Installation Codes, or applicable provisions of the local building codes.
The required free area of supply air opening is: 13 in. sq. (8,387 mm2), for GS 100
23 in. sq. (14,839 mm2), for GS 200
35 in. Sq. (22,581 mm2), for GS 300 47 in. Sq. (30,323 mm2), for GS 400 59 in. Sq. (38,064 mm2), for GS 500
71 in. Sq. ( 45,806 mm2), for GS 600
Cabinet top and bottom contain air openings to provide combustion air to the forced draft blower. DO NOT BLOCK THESE OPENINGS.
Excessive exposure to contaminated combustion air will result in safety and performance related problems. Known contaminates include halogens, ammonia, and chlorides, excessive dust, lime or dirt. Excessive exposure of electronics to the contaminants will also result in performance related problems. Contact NORTEC Technical Services if you have any questions. If contaminants exist, isolate the unit from the contaminated space.
DIRECT VENT GUIDELINES
Installation of the combustion air supply line must be carried out by adequately qualified personnel. All local regulations relating to the provision of air supply systems must be observed and adhered to.
The maximum pipe length for the air supply line and exhaust is equivalent to 70’ (21m). The vent pipe diameter must be maintained over the overall length of the vent.
All air piping must be listed type for direct vent application with sealed joints and seams, such as Z flex.
The air supply line should be approximately as long as the flue gas venting and must be supported at every 5 ft. (1.5 m) and additionally at every pipe bend.
The air supply line must be installed with air supply terminals provided.
At low temperatures, water condensation can form on the outside of the pipe. To prevent this, it is
recommended that the supply air line is insulated and an in line heat is added. Consult factory.
Attach the air supply line to the manifold using a hose clamp or hose coupling if required. See Figure #4.
WARNING: Air supply line should not obstruct any services going to the humidifier front and right side cabinet panels.
WARNING: BH Type venting must be used in a direct vent application.
The air intake terminal and the flue gas terminal must end at an outside location. See Figure #5.
Air Piping Insulated (by others)
Hose Coupling 
(by others)
Air Intake Connection
Figure #5
Direct Vent Side Wall Requirements
Exhaust terminal with opening vertical.
Intake terminal with opening vertical.
4 ft - 6 ft
(1.2 m - 1.83 m)
Keep 6“ (15.2 cm) away from sidewall.
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