Installation & Operation Manual
2
Venting
(continued)
Length of air inlet pipe
The installed length of air inlet pipe from the unit to the outside air inlet cap must not exceed 50 equivalent feet (15.2m). Subtract
5 feet (1.5m) of equivalent length for each 90° elbow. Subtract 2.5 feet (0.7m) of equivalent length for each 45° elbow.
Do not exceed the limits for the combustion air inlet piping lengths.
Connecting the air inlet pipe to the unit
Connect the air inlet piping directly to the unit by attaching it to the DV box adapter. The DV box adapter is included in the direct
vent kits. The combustion air inlet area of the unit is located at the right rear corner of the unit. This unit uses a simple air filter
to ensure clean air is used for the combustion process. Attach the DV box adapter over the air filter (see FIG. 2-10). Align screw
holes on the DV box adapter with the screw holes surrounding the air filter hanger. Insert sheet metal screws and tighten firmly.
For venting versatility, you can move the air filter assembly and DV box adapter to the right side of the unit. Remove the metal
panel on the unit’s right side (see FIG. 2-11). Remove the filter/bracket assembly from the rear of the unit. Attach the filter/bracket
assembly and DV box adapter to the right side opening using the pre-drilled screw holes. Make sure you attach the metal panel to
the rear combustion air opening of the unit.
The DV box adapter has an air inlet pipe mounting ring. Connect combustion air inlet piping to the direct vent box mounting ring.
Figure 2-10_Attaching DV Box Adapter to Unit
Figure 2-11_Moving Air Filter Assembly & DV Box Adapter
VERTICAL DV BOX ADAPTER
HORIZONTAL DV BOX ADAPTER
Air inlet piping materials
The air inlet pipe(s) must be sealed. Select air inlet pipe material from the following specified materials.
•
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 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 unit and the plastic air
inlet
pipe.
WARNING
Use only vent or air intake materials specified in this manual. Follow vent pipe manufacturer’s instructions.
Failure to do so can result in property damage, personal injury, or death. Mixing of venting materials will void
the warranty and certification of this unit.
Sealing Type-B double-wall vent pipe or galvanized vent pipe
Follow the steps below to properly seal Type-B double-wall vent pipe or galvanized vent pipe.
1. Seal all joints and seams of the air inlet pipe using either aluminum foil duct tape meeting UL Standard 723 or 181 A-P or a
high quality UL Listed silicon sealant such as those manufactured by Dow Corning or General Electric.
2. On horizontal runs, do not install vent pipe with seams pointing down. Position vent pipe so that the seams are on the top side
of the vent pipe.
3. 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.
4. Ensure that the air inlet pipes are properly supported.
Sealing PVC, CPVC, ABS, dryer vent, and flex duct vent pipe
1. Clean the PVC, CPVC, or ABS air inlet pipe using the pipe manufacturer’s recommended solvents. Seal the pipe joints using
standard commercial pipe cement.
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