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Installation & Operation Manual
24
2 Venting
Vertical Air Inlet: Vent options B, F, & H
Vertical combustion air inlet
The air inlet cap for the vertical rooftop air inlet is assembled from components purchased locally. The air inlet cap consists 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 (152mm) in length. The termination elbow on the air inlet must be located a minimum of 12 inches
(0.30m) above the roof or above normal levels of snow accumulation.
Location of a vertical 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.
The point of termination for the combustion air inlet cap MUST be at least 3 feet (0.91m) below the point of flue gas termination
(vent cap) if it is located within a 10 foot (3.05m) radius of the flue outlet. Use care to ensure that the 90° elbow assembly is properly
installed on the air inlet pipe.
The combustion air inlet cap must not be installed closer than 10 feet (3.05m) from an inside corner of an L-shaped structure.
The termination point of the combustion air inlet cap must be installed at least one foot (0.30m) above the rooftop and above
normal snow levels.
The combustion air cap assembly used MUST adequately protect the combustion air inlet from wind and weather.
Combustion air supplied from outdoors must be free of contaminants (see Combustion and Ventilation Air, page 10). To prevent
recirculation of flue products into the combustion air inlet, follow all instructions in this section.
The combustion air inlet caps for multiple appliance installations must maintain the minimum 3 foot (0.91m) clearance below the
closest vertical flue outlet if within 10 feet (3.05m).
Figure 2-4_Vertical Air Inlet Clearances