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VERTICAL COMBUSTION |
| HORIZONTAL |
AIR INLET |
| WITH SIDEWALL COMBUSTION AIR |
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FIG. 30 Air Inlet Cap for Rooftop Termination
The air inlet cap for the vertical roof top air inlet is assembled from components purchased locally. The air inlet cap consist of two 90° elbows installed at the point of termination for the air inlet pipe. The first 90° elbow is installed on the rooftop at the highest vertical point of the air inlet pipe and turned horizontal, the second 90° elbow is installed on the horizontal outlet of the first elbow and turned down. A 90° elbow and a 90° street elbow may be used to make this assembly. If a straight piece of pipe is used between the two elbows, it should not exceed 6 inches (150 mm) in length. The termination elbow on the air inlet must be located a minimum of 12 inches (0.30 m) above the roof or above normal levels of snow accumulation.
Location of a Rooftop Air Inlet Cap
Incorrect installation and/or location of the air inlet cap can allow the discharge of flue products to be drawn into the combustion process on the heater. This can result in incomplete combustion and potentially hazardous levels of carbon monoxide in the flue products. This will cause operational problems with the heater and possible spillage of flue products that can cause personal injury, death or property damage.
Installation, location and clearance requirements for the rooftop air inlet cap in an
The rooftop combustion air inlet cap and the sidewall flue gas outlet are located in different pressure zones in an
Combustion air supplied from outdoors must be free of contaminants (see Combustion and Ventilation Air). To prevent recirculation of flue products in to the combustion air inlet, follow all instructions in this section and related Direct Vent sections.
Follow all requirements in the General Category IV Venting sections for proper installation and of venting flue products horizontally to the outdoors. All other general installation requirements must be followed.
The
FIG. 31 Horizontal Intelli-Fin Installation with Sidewall
Combustion Air in a Different Pressure Zone
In cold climates, the use of type “B” double wall vent pipe or an insulated single wall pipe is recommended to help prevent moisture in the cool incoming air from condensing and leaking from the inlet pipe.
Termination point for the flue products must follow the clearance requirements in the Horizontal Sidewall Vent Termination section of the Category IV Venting.
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