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Installation & Operation Manual
26
2 Venting
Length of air inlet pipe for both vertical and horizontal - Vent options:
All Categories
The maximum installed length of the air inlet pipe from the appliance to the air inlet cap is 50 equivalent feet (15.2m) in length.
Subtract 5 feet (1.52m) of equivalent length for each 90° elbow installed in the air inlet pipe. Subtract 2 1/2 feet (0.7m) of equivalent
length for each 45° elbow installed in the air inlet pipe.
Air inlet pipe materials:
The air inlet pipe(s) must be sealed. Choose acceptable combustion air inlet pipe materials from the following list:
PVC, CPVC or ABS
Dryer Vent or Sealed Flexible Duct (not recommended for rooftop air inlet)
Galvanized steel vent pipe with joints and seams sealed as specified in this section.
Type “B” double-wall vent with joints and seams sealed as specified in this section.
*Plastic pipe may require an adapter (not provided) to transition between the air inlet connection on the appliance and the plastic
air inlet pipe.
ƽ WARNING
Using vent or air intake materials other than those specified, failure to properly seal all seams and joints or failure
to follow vent pipe manufacturer’s instructions can result in personal injury, death or property damage. Mixing
of venting materials will void the warranty and certification of the appliance.
NOTICE
The use of double-wall vent or insulated material for the combustion air inlet pipe is recommended in cold
climates to prevent the condensation of airborne moisture in the incoming combustion air.
Sealing of Type “B” double-wall vent material or galvanized vent pipe material used for air inlet piping on a sidewall or vertical
rooftop Combustion Air Supply System:
a. Seal all joints and seams of the air inlet pipe using either Aluminum Foil Duct Tape meeting UL Standard 723 or 181A-P or a
high quality UL Listed silicone sealant such as those manufactured by Dow Corning or General Electric.
b. Do not install seams of vent pipe on the bottom of horizontal runs.
c. Secure all joints with a minimum of three sheet metal screws or pop rivets. Apply Aluminum Foil Duct Tape or silicone sealant
to all screws or rivets installed in the vent pipe.
d. Ensure that the air inlet pipes are properly supported.
The PVC, CPVC, or ABS air inlet pipe should be cleaned and sealed with the pipe manufacturer’s recommended solvents and
standard commercial pipe cement for the material used. The PVC, CPVC, ABS, Dryer Vent or Flex Duct air inlet pipe should use a
silicone sealant to ensure a proper seal at the appliance connection and the air inlet cap connection. Dryer vent or flex duct should
use a screw type clamp to seal the vent to the appliance air inlet and the air inlet cap. Proper sealing of the air inlet pipe ensures
that combustion air will be free of contaminants and supplied in proper volume.
When a sidewall or vertical rooftop combustion air supply system is disconnected for any reason, the air inlet pipe must be resealed
to ensure that combustion air will be free of contaminants and supplied in proper volume.
ƽ DANGER
Failure to properly seal all joints and seams as required in the air inlet piping may result in flue gas recirculation,
spillage of flue products and carbon monoxide emissions causing severe personal injury or death.
Combined combustion air inlet points - Category I, II, & IV
The air inlet pipes from multiple appliances can be combined to a single common connection if the common air inlet pipe has a
cross sectional area equal to or larger than the total area of all air inlet pipes connected to the common air inlet pipe. [Example:
two 8" (20.3cm) air inlet pipes (50.3 in
2
(324.5cm
2
) area each) have a total area of 100.6 in
2
(645.2cm
2
) requires a 12 inch (30.5cm)
(113.1in
2
area) (729.7cm
2
) common air inlet pipe.] The air inlet point for multiple boiler air inlets must be provided with an exterior
opening which has a free area equal to or greater than the total area of all air inlet pipes connected to the common air inlet. This
exterior opening for combustion air must connect directly to the outdoors. The total length of the combined air inlet pipe must
not exceed a maximum of 50 equivalent feet (15.2m). You must deduct the restriction in area provided by any screens, grills, or
louvers installed in the common air inlet point. These (screens, grills, or louvers) are common on the sidewall air inlet openings
and some rooftop terminations. Screens, grills, or louvers installed in the common air inlet can reduce the free area of the opening
from 25% to 75% based on the materials used.