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Select air inlet pipe material from the following specified
materials:
PVC, CPVC or ABS (6", 7"or 8" I.D.)*
Dryer Vent or Sealed Flexible Duct (not recommended for
roof top air inlet)
Galvanized steel vent pipe with joints and seams sealed as
specified below.
Type "B" double wall vent with joints and seams sealed as
specified below
* Plastic pipe may require an adapter (not provided) to
transition between the air inlet connection on the appliance
and the plastic air inlet pipe.
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.
NOTE:
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 pipe on
a sidewall or vertical roof top 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 silicon
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 manufacturers 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 roof top 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.
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
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" (20.3 cm) air inlet
pipes (50.3 in
2
(324.5 cm
100.6 in
2
(645.2 cm
2
) requires a 12 inches (30.5 cm) (113.1
in
2
area) (729.7 cm
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 (15.2 m) equivalent feet. You must deduct the restriction
in area provided by any screens, grills or louvers installed
in the common air inlet point. These 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.
VERTICAL DIRECT
VENT SYSTEMS
A Vertical 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.
combustion air intake must both terminate on the rooftop.
15
2
) area each) have a total area of
The flue outlet and
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