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4 Vertical direct venting
Vent/air termination – vertical
Prepare roof penetrations
1. Air pipe penetration:
a. Cut a hole for the air pipe. Size the air pipe hole as
close as desired to the air pipe outside diameter.
2. Vent pipe penetration:
a. Cut a hole for the vent pipe. For either
combustible or noncombustible construction, size
the vent pipe hole with at least a 1/2 inch clearance
around the vent pipe outer diameter:
• 4½ inch hole for 3 inch vent pipe
• 5½ inch hole for 4 inch vent pipe
b. Insert a galvanized metal thimble in the vent pipe
hole.
3. Space the air and vent holes to provide the minimum
spacing shown in FIG. 4-1, page 25.
4. Follow all local codes for isolation of vent pipe when
passing through floors, ceilings, and roofs.
5. Provide flashing and sealing boots sized for the vent
pipe and air pipe.
Termination and fittings
1. Prepare the vent termination coupling and the air
termination elbow (FIG. 4-1) by inserting the bird
screens provided with the water heater. Bird screens are
provided for either 3" (Models SNR150-100 --
SNR200-100) or 4" (Models SNA285-125 --
SNA500-125) fittings.
2. The air piping must terminate in a down-turned 180°
return bend as shown in FIG. 4-1. Locate the air inlet
pipe no further than 2 feet from the center of the vent
pipe. This placement avoids recirculation of flue
products into the combustion air stream.
3. The vent piping must terminate in an up-turned
coupling as shown in FIG. 4-1. The top of the coupling
must be at least 1 foot above the air intake. The air inlet
pipe and vent pipe can be located in any desired
position on the roof, but must always be no further than
2 feet apart and with the vent termination at least 1 foot
above the air intake.
4. Maintain the required dimensions of the finished
termination piping as shown in FIG. 4-1.
5. Do not extend exposed vent pipe outside of building
more than shown in this document. Condensate could
freeze and block vent pipe.
Multiple vent/air terminations
1. When terminating multiple Shield water heaters, terminate
each vent/air connection as described in this manual
(FIG. 4-2).
Terminate all vent pipes at the same height
and all air pipes at the same height to avoid
possibility of severe personal injury, death,
or substantial property damage.
2. Place roof penetrations to obtain minimum clearance of
12 inches between edge of air intake elbow and adjacent
vent pipe of another water heater for U.S. installations (see
FIG. 4-2). For Canadian installations, provide clearances
required by CSA B149.1 Installation Code.
3. The air inlet of a Shield water heater is part of a direct vent
connection. It is not classified as a forced air intake with
regard to spacing from adjacent water heater vents.
Figure 4-2 Vertical Terminations with Multiple Water
Heaters
Figure 4-3 Alternate Vertical Terminations with Multiple
Water Heaters
ƽ WARNING
Installation & Service Manual
TM