VERTICAL COMBUSTION AIR INLET | Incorrect installation and/or location of the air inlet cap can allow | ||||||||||||||||||||||||||||
the discharge of flue products to be drawn into the combustion | |||||||||||||||||||||||||||||
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| process on the heater. This can result in incomplete combustion | ||||||||||||||||||||
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| and potentially hazardous levels of carbon monoxide in the flue | ||||||||||||||||||||
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| products. This will cause operational problems with the heater and | ||||||||||||||||||||
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| possible spillage of flue products that can cause personal injury, | ||||||||||||||||||||
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| death or property damage. | ||||||||||||||||||||
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| Multiple Vertical Direct Vent Installations | ||||||||||||||||||||
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FIG. 21 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" (150 mm) in length. The termination elbow on the air inlet must be located a minimum of 12" (0.30 m) above the roof or above normal levels of snow accumulation.
The point of termination for the combustion air inlet cap MUST be at least 3 feet (0.91 m) below the point of flue gas termination (vent cap) if it is located within a 10 foot (3.05 m) 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 (3.05 m) from an inside corner of an
The termination point of the combustion air inlet cap must be installed at least one foot (0.30 m) 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.
The combustion air cap and flue gas outlet MUST be located on the same roof top surface and in the same pressure zone.
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.
FIG. 22 Multiple Vertical Direct Vent Installations
The combustion air inlet caps for multiple appliance installations must maintain the minimum 3 foot (0.91 m) clearance below the closest vertical flue outlet if within 10 feet (3.05 m). Multiple flue outlet caps may be installed side by side and multiple air inlet caps may be installed side by side but the air inlet must always be at least 3 feet (0.91 m) below the closest flue outlet if the outlet is within 10 feet (3.05 m). All clearance and installation requirements in this section and the applicable portions of the general Category IV venting section must be maintained on multiple appliance installations.
HORIZONTAL DIRECT VENT
For venting flue products horizontally to the outdoors, follow all requirements in the installation instructions for sidewall venting. Termination point for the flue products must follow the clearance requirements in the Sidewall Vent Termination section of Category IV Venting.
A Horizontal Direct Vent System is installed with a Category IV flue and a separate combustion air pipe to the outdoors. The Direct Vent system terminates both the flue and air inlet in the same pressure zone. The flue outlet and combustion air intake must both terminate on the same sidewall.
Follow all requirements in the General Category IV Venting sections for proper installation and of venting flue products to the outdoors with a sidewall termination. All other general installation requirements must be followed.
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