A.O. Smith 300 Series Instruction Manual page 32

Cement water heater combustion air intake and vent pipes to
7.
concentric vent termination assembly. See Figure 33 (page 31)
for proper pipe attachment.
Operate heater through 1 heat cycle to ensure combustion air and
8.
vent pipes are properly connected to concentric vent termination
connections.
FLAT ROOF INSTALLATION
When installing a concentric termination vertically through a flat roof,
the termination's vent cap must be a minimum of 18" (450 mm) away
from any parapet, vertical wall or structure as shown in Figure 34.
If this required 18" (450 mm) distance to a parapet, vertical wall or
structure cannot be maintained, standard terminations must be used.
See Vertical Vent Terminal Installation (page 26).
CONCENTRIC TERMINATION(S)
MUST BE A MINIMUM OF
18" 450 mm AWAY FROM ANY
PARAPET, VERTICAL WALL
OR STRUCTURE.
CONCENTRIC TERMINATION
FLAT ROOF CLEARANCE
Figure 34. Installation Concentric Flat-Roof Termination
Figure 35. Installation of Side Wall Termination
Determine best location for termination kit.
1.
Note: Consideration for the following should be used when
determining an appropriate location for the termination kit:
• Termination kit positioned where the vent vapors will not
damage plants/shrubs or air conditioning equipment.
• Termination kit positioned so it will not be affected by wind
eddy that may allow recirculation of combustion products, or
airborne leaves, or light snow.
• Termination kit positioned where it will not get damaged or
be subjected to foreign objects, such as stones, balls, etc.
• Termination kit positioned where the vent vapors will not be
objectionable.
Note: See Venting Installation (page 23) in this manual for
additional vent location requirements.
Cut 1 hole (5 in. diameter).
2.
Partially assemble concentric vent termination kit.
3.
A. Cement the Y concentric fitting to larger diameter kit pipe.
See Figure 30 (page 31).
B. Cement the rain cap to the smaller diameter kit pipe. See
Figure 30 (page 31).
Note: Instead of cementing the smaller pipe to the rain cap, a
field-supplied stainless steel screw may be used to secure
the 2 components together when field disassembly is
desired for cleaning. See Figure 32 (page 31).
When using alternate screw assembly method, drill clearance
hole in rain cap and pilot hole in vent pipe for screw being used.
Failure to drill adequate holes may cause cracking of PVC
components, allowing combustion products to be recirculated.
Failure to follow this warning could result in personal injury or
death.
Do not operate the heater with rain cap removed or recirculation
of combustion products may occur. Water may also collect inside
larger combustion-air pipe and flow to the burner enclosure.
Failure to follow this warning could result in product damage
or improper operation, personal injury or death.
Install Y concentric fitting and pipe assembly through structure's
4.
hole.
Note: Do not allow insulation or other materials to accumulate
inside pipe assembly when installing through hole.
A. Install rain cap and small diameter pipe assembly in Y
concentric fitting and large pipe assembly. Ensure small
diameter pipe is bottomed and cemented in Y concentric
fitting.
B. Ensure the Y connection is oriented so the air intake side
of Y is on top. See Figure 36 (page 33).
C. Secure assembly to structure as shown in Figure 36 (page
33) using field-supplied metal strapping or equivalent
support material.
Note: Ensure termination location clearance dimensions are
as shown in Figure 35, Figure 37 (page 33) and Figure 38
(page 33). When extending the length of the 4" pipe,
the added length beyond 21-1/8" must be deducted from
the maximum equivalent feet of vent pipe.
Note: If assembly needs to be extended to allow side wall
thickness requirement, the 2 pipes supplied in the kit may
be replaced by using same diameter, field-supplied SDR-
26 PVC (D2241) pipe. Do not extend 21 1/8" (53.6 cm)
dimension more than 60" (1.5 m). See Figure 35.
Do not use field-supplied couplings to extend pipes. Airflow
restriction will occur and the heater pressure switch may cause
intermittent operation.
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