A.O. Smith 3400 User Manual
Page 28
28
HORIZONTAL INSTALLATION REQUIREMENTS
1. The vent system must terminate with the Through-the-Wall
Termination (TWT) kits. Do not locate the terminal within 8
feet (2.4 m) of an inside corner of a building or adjacent to
outside walls, shrubs or other such objects that may cause
adverse wind conditions in the immediate area.
2. 2. The TWT should be located not less than 12 inches (305
mm) above grade or, in geographical areas where snow
accumulates, no less than 12 inches (305 mm) above
anticipated snow line. Ensure that TWT is protected against
blockage which may occur during ice buildup or snowstorms.
The TWT should terminate at least 3 feet (0.9 m) above
any forced air inlet within 10 feet (3 m), except when the
forced air inlet is the combustion air intake of a direct vent
appliance. The TWT should terminate at least 4 feet (1.2
m) below, 4 feet (1.2 m) horizontally from or 1 foot (305
mm) above any door, window or gravity air inlet into any
building as provided in the current edition of the national fuel
gas code ANSI Z223.1. In addition, a minimum clearance
of 4 feet (1.2 m) horizontally from, and in no case above
or below, unless the 4 feet (1.2 m) of horizontal distance is
maintained from electric meters, gas meters, regulators and
relief equipment.
3. This horizontal exhaust vent system must pitch upward
toward the termination at 1/4 inch per foot (21 mm per
meter).
4. The TWT is designed such that the building is protected
from degradation by flue gas and condensate. However,
if additional protection is desired, install against the wall a
non-corrosive metal sheet under the TWT.
5. Due to the normal formation of water vapor in the combustion
process, horizontal terminations must not be located over
areas of pedestrian or vehicular traffic, (i.e., public walkways
or over areas where condensate could create a nuisance or
hazard). This is especially true in colder climates where ice
buildup is likely to occur. A. O. Smith Corporation will not be
held liable for any personal injury or property damage due to
any dislodging of ice.
DIRECT VENT INSTALLATION REQUIREMENTS
The labels in the Direct Vent Kit must be affixed to the boiler in
locations specified by the instruction sheet provided in the kit.
The following are requirements for the Air-Intake Terminal (AIT):
1. The Air-Intake System (AIS) must terminate with the venting
equipment provided with the boiler.
2. The AIT should not be located less than 3 feet (0.9 m) below
any exhaust vent within 10 feet (3 m).
3. The total horizontal distance of the AIS from the boiler’s
Blower Adapter to the outside of the “AIT” should not be
greater than 100 equivalent feet (30.5 m) of vent pipe nor
less than 3 feet (0.9 m), including elbows.
VENTING SUPPORTS
Care must be taken in the installation of the venting system
that adequate support is maintained throughout the installation
process. When extending more than 10 feet (3 m) vertically,
vertical support kits are required once every 10 feet (3 m) of
vertical run. Vertical support is also required immediately after
any transition (elbow, tee, etc.) to vertical of over 10 feet (3 m) of
run and after any offset in the vertical run.
The support brackets (supplied in the Vertical Support Kit)
are to be securely fastened to a solid vertical member of the
building using the appropriate fasteners; i.e., wood screws for
wood framing, machine or tapping screws for structural steel
or masonry anchors for solid masonry. The bracket should be
located so that it will not interfere with any joints of the venting
system. The bottom most support bracket should be located
directly above the first transition from horizontal to vertical.
If a means of support for the brackets is not available and
horizontal vent sections are present, install hanger straps
(made from non-combustible material) as close to the points of
transition as possible. If the horizontal portions of the vent and/or
vent connector are longer than 6 feet (1.8 m), then install hanger
straps every 6 feet (1.8 m) to support the connector.
Do not rivet or screw the straps to the conduit or otherwise
puncture the conduit wall. Instead, wrap an extra loop of strap
around the conduit to hold it in position, or attach the strap to
the center screw of the double wall AL 29-4C® vent coupling, if
applicable.
VERTICAL INSTALLATION REQUIREMENTS
1. The vent system must terminate at least 3 feet (0.9 m) and
no more than 6 feet (1.8 m) above the roof line and no closer
than 10 feet (3 m) from any wall or vertical structure. If the
exhaust vent terminal is within 10 feet (3 m) of a wall or
parapet, it must extend a minimum of 2 feet (0.6 m) above
the wall or parapet, see Figure 24 on Page 29 and Figure
2. For direct vent installations, the total distance of the vent
system from the boiler vent connector to the vertical vent
termination should not exceed 100 equivalent feet (30.5 m).
Minimum vertical vent is 10 equivalent feet (3 m) for direct
vent installations. Standard minimum vertical vent length is
10 feet (3 m). See Figure 24, Figure 27 thru Figure 29 for
differences between standard and direct vent installations.
3. Maintain a minimum of 4 feet (1.2 m) separation between
the air intake and the exhaust terminals.