A.O. Smith VB/VW- 1000 - Manual (Page 17)

17
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 (3.0m) vertically, vertical support
kits are required once every 10 feet (3.0m) of vertical run. Vertical
support is also re quired immedi ately after any transi tion (elbow,
tee, etc.) to vertical of over 10 feet (3.0m) of run and after any
offset in the vertical run.
The support brackets (supplied in the Vertical Support Kit) are to be
secure ly 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, see Figure
10. Refer to Figures 12, 12A, 12B and 12C.
If a means of support for the brackets are 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 (2.0m), then install hanger
straps every 6 feet (2.0m) to support the connector.
DO NOT rivet or screw the straps to the conduit or other wise
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
applica ble.
VERTICAL INSTALLATION REQUIREMENTS
1. The vent system must terminate at least 3 feet (1.0m)
and no more than 6 feet (2.0m) above the roof line and
no closer than 10 feet (3.0m) from any wall or verti cal
structure. If the exhaust vent terminal is within 10 feet
(3.0m) of a wall or parapet, it must extend a minimum of
2 feet (610mm) above the wall or parapet, see Figures
11 and 12A.
2. For direct vent installations, the total distance of the vent system
from the boiler vent connector to the vertical vent termination shall
not exceed 70 equivalent feet (21.3m). A maximum of three 90°
elbows can be used. Minimum vertical vent is 7 equivalent feet
(2.1m) for direct vent installations. Standard minimum vertical vent
length is 7 feet (2.1m), plus Boot-Tee. See Figures 11, 12A, 12B, and
12C for differences between standard and direct vent installations.
3. An AL 29-C ® Vent Vertical Vent Terminal must be used at
the termina tion.
4. Maintain a minimum of 6 feet (2.0m) separation between
the air intake and the exhaust terminals.
HORIzONTAL INSTALLTION REQUIREMENTS
1. The vent system must terminate with a AL 29-4C ® Vent
Through-the-Wall Termination (TWT). Plan the terminal
location based on the dimensions shown in Figure 9. Do
not locate the terminal within 8 feet (2.5m) 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. The TWT shall be located not less than 12 inches (305mm)
above grade or, in geographical areas where snow
accumu lates, no less than 12 inches (305mm) above the
antici pated snow line. Ensure that the TWT is protected
against blockage which may occur during ice build up or
snowstorms.
The TWT shall terminate at least 3 feet (1.0m) above
any forced air inlet within 10 feet (3.0m), except when
the forced air inlet is the combustion air intake of a
direct vent appliance. The TWT shall terminate at least
4 feet (1.2m) below, 4 feet (1.2m) horizontally from or
1 foot (305mm) above any door, window or gravity air
inlet into any building as provided in the current edition
of the NATION AL FUEL GAS CODE ANSI Z223.1, see
Figure 9.
In addition, a minimum clearance of 4 feet (1.2m) hori-
zontally from, and in NO CASE ABOVE OR BELOW,
unless the 4 feet (1.2m) of horizontal distance is main-
tained 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 (21mm per meter).
4. The TWT is designed such that the building is protected
from degradation by flue gas and condensate. Howev er,
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 combus-
tion process, horizon tal 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 dislodg ing of ice.