Sizing; Minimum/ Maximum Allowable Combustion Air And Vent Piping Lengths Are As Follows; Air Inlet Pipe Materials - Smith XWH 150 Instruction Manual

SIZING

This water heater uses model specific combustion air intake and
vent piping sizes as detailed in Table below.
Table 8. Air Intake/Vent Piping Sizes
MODEL AIR INTAKE
150 - 200
285 - 600
700 - 800
NOTE: Increasing or decreasing combustion air or vent piping sizes is not
authorized.
MINIMUM/ MAXIMUM ALLOWABLE COMBUSTION AIR
AND VENT PIPING LENGTHS ARE AS FOLLOWS
Combustion Air = 12 equivalent feet minimum / 100 equivalent
feet maximum.
Vent = 12 equivalent feet minimum / 100 equivalent feet
maximum.
NOTE: When using the alternative 3" vent and combustion
air piping with an XWH 285 model, the maximum allowable
combustion air and vent piping lengths are limited to 60 equivalent
feet each. The minimum allowable combustion air and vent pipe
lengths remain 12 equivalent feet each.
When determining equivalent combustion air and vent length,
add 5 feet for each 90° elbow and 3 feet for each 45° elbow.
EXAMPLE: 20 feet of PVC pipe + (4) 90° elbows + (2) 45° elbows
+ (1) concentric vent kit (100274637) = 49 equivalent feet of
piping.
NOTE: The appliance output rating will reduce by up to 1.5% for
each 25 feet of vent length, except when using the alternative 3"
vent for the XWH 285 model which may de-rate by up to 4% for
each 25 feet of vent length.
Table 9. Concentric Vent Kit Equivalent Vent Lengths
MODEL KIT NUMBER
150 - 200 100274637
285 100274638
400 100274638
500 - 600 100274638

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, Polypropylene or ABS
• 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.
• AL29-4C, stainless steel material to be sealed to specification
of its manufacturer.
*Plastic pipe may require an adapter (not provided) to transition
between the air inlet connection on the appliance and the plastic
air inlet pipe.
Using air intake materials other than those specified can result in
personal injury, death or property damage.
VENT
3 inches 3 inches
4 inches 4 inches
4 inches 6 inches
EQUIVALENT
VENT LENGTH
3 feet
3 feet
5 feet
30 feet
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 piping on a sidewall or vertical
rooftop Combustion Air Supply System:
• 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.
• Do not install seams of vent pipe on the bottom of horizontal
runs.
• Secure all joints with a minimum of three (3) sheet metal
screws or pop rivets. Apply Aluminum Foil Duct Tape or
silicone sealant to all screws or rivets installed in the vent
pipe.
• 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.
Follow the polypropylene manufacturer's instructions when using
polypropylene material as an inlet pipe.
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.
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.
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