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Air intake/vent connections
1. Combustion Air Intake Connector (FIG.’s 2-5 and 2-6)
- Used to provide combustion air directly to the unit
from outdoors. A fitting is provided on the unit for final
connection. Combustion air piping must be supported
per guidelines listed in the National Mechanical Code,
Section 305, Table 305.4 or as local codes dictate.
2. Vent Connector (FIG.’s 2-5 and 2-6) - Used to provide
a passageway for conveying combustion gases to the
outside. A transition fitting is provided on the unit for
final connection. Vent piping must be supported per the
National Building Code, Section 305, Table 305.4 or as
local codes dictate.
VENT
AIR
3" CPVC PIPE INSTALLED IN THE
WATER HEATER MUST BE USED
FOR VENT CONNECTION
NOTE: CPVC VENT PIPE AND VENT FITTINGS MUST BE USED
IN CLOSET AND ALCOVE INSTALLATIONS.
Figure 2-5 Near Water Heater Venting Models
SNR150-100 - SNR200-100
VENT
AIR
4" CPVC PIPE INSTALLED IN THE
WATER HEATER MUST BE USED
FOR VENT CONNECTION
NOTE: CPVC VENT PIPE AND VENT FITTINGS MUST BE USED
IN CLOSET AND ALCOVE INSTALLATIONS.
Figure 2-6 Near Water Heater Venting Models
SNA285-125 - SNA500-125
The Shield water heater uses model specific combustion air
intake and vent piping sizes as detailed in Table 2B below.
Model Air Intake Vent
SNR150-100 -- SNR200-100 3 inches 3 inches
SNA285-125 -- SNA500-125 4 inches 4 inches
Table 2B Air Intake/Vent Piping Sizes
Increasing or decreasing combustion air or
vent piping is not authorized.
NOTICE
2 General venting
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.
Installation & Service Manual
TM
Models SNA400-125 and SNA500-125 will de-rate 1.75% per
25 feet of vent when installed as direct vent or 0.75% per 25 feet
of vent when drawing combustion air from the room.
Models SNR150-100 through SNA285-125 will de-rate up to 1%
per 25 feet of vent pipe when installed as direct vent, but will not
de-rate when drawing combustion air from the room.