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17
The Direct Vent system requires the installation of an additional
pipe to supply combustion air from outdoors directly to the
appliance. The air inlet pipe must use one of the spec i fied
materials.
The maximum installed length of the air inlet pipe from the
appliance to the air inlet cap is 100 equivalent feet (30.48 m) in
length. The maximum in stalled length of the flue pipe from the
appliance to the termination cap is 100 equivalent feet
(30.48 m) in length. Subtract 5 feet (1.52 m) of equivalent
length for each 90° elbow installed in either the flue pipe or the
air inlet pipe. Subtract 2 1/2 feet (0.7 m) of equivalent length for
each 45° elbow installed in either the flue or the air inlet pipe.
Termination point for the flue products must follow the clearance
requirements in the Sidewall Venting Termination sections of the
Category IV Venting.
FIG. 23 Horizontal Direct Vent Installations with Sidewall
Combustion Air Inlet
SIDEWALL COMBUSTION
AIR INLET
Horizontal Direct Vent systems in stalled with sidewall terminations
for both combustion air and flue products must purchase the
termination caps from the appliance manufacturer. The sidewall
air inlet cap and sidewall vent cap for flue products are avail able as
a vent kit.
FIG. 24 Sidewall Vent Cap
The part numbers for the required sidewall air inlet cap kit are listed
by unit size. The manufacturer, in accordance with CSA
requirements, must furnish the sidewall air inlet cap. Each kit
includes the spe cial combustion air inlet cap for in stal la tion on an
exterior sidewall. The sidewall air inlet cap supplied in the kit is
sized to provide combustion air for a single appliance only.
TABLE - G
Flue Air Inlet Sidewall Air
Input Cap Cap Inlet & Flue
Btu/hr Size Size Cap Kit
1,500,000
___________
1,700,000
___________
2,000,000
6"
__________
7"
__________
8"
6"
__________
8"*
__________
8"
HDK3018
______________
HDK3019
______________
HDK3020
*Piping from the appliance to the air inlet cap may be either 7" or
8" connecting to an 8" sidewall cap provided in the kit.
Location of a Sidewall 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 prop er ty damage.
The termination point of the sidewall air inlet must be installed a
minimum of 12 inches (0.30 m) above ground level and above
normal levels of snow ac cu mu la tion.
The point of termination for the sidewall combustion air inlet cap
MUST be located a minimum of 3 feet (0.92 m) horizontally and
12 inches (0.30 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.