Sidewall/Power Venting - A.O. Smith 400 - 2100 Installation & Operation Manual

2
Venting
(continued)
Sidewall venting
C
NOTICE
This option uses a powered vent assembly which pulls the flue products out of the stack. This fan generates a negative
draft at the unit. Combustion air is drawn from the equipment room (see Combustion and Ventilation Air on 10).
Sidewall with fan
The sidewall fan can be mounted on the inside/outside (depending upon model) with a sidewall vent hood installed
on the exterior wall. The sidewall fan and accessories are included in a venting kit provided by the appliance
manufacturer. See Table 2C on page 25 for kit numbers.
The venting kit includes the sidewall fan, vent hood, tapered vent adapter, barometric damper (1000 - 2100 Models),
proving switch and all necessary relays to interlock with the heaters control system. The tapered vent adapter reduces
the vent size at the inlet to the fan. There should be no reduction in vent diameter from the unit's flue outlet to the
sidewall fan. The barometric damper must be installed on the flue and adjusted to supply a negative draft within the
range of 0.04 to 0.08 inches w.c. while unit is operating.
Flue outlet piping
With this venting option, you must use Type-B double-wall (or equivalent) vent materials. Vent materials must be
listed by a nationally-recognized test agency for use as vent materials. Make the connections from the unit vent to the
sidewall fan/cap as direct as possible with no reduction in diameter. Use the National Fuel Gas Code venting tables
for double-wall vent to properly size all vent connectors and stacks. Follow the vent manufacturer's instructions
when installing Type-B vents and accessories, such as firestop spacers, vent connectors, thimbles, caps, etc.
When planning the venting system, avoid possible contact with plumbing or electrical wiring inside walls.
The maximum installed length of sidewall vent pipe with an induced draft fan must not exceed 100 feet (30.5m).
Subtract 5 feet (1.5m) for each 90° elbow. Subtract 2.5 feet (0.7m) for each 45° elbow.
Sidewall venting termination
The sidewall vent cap must be installed on an exterior sidewall. The sidewall fan/powered sidewall vent cap and
accessories are included in a venting kit which is furnished by the appliance manufacturer in accordance with CSA
International requirements. This venting kit includes the powered sidewall fan/cap, proving switch and all necessary
relays to interlock with the heaters control system.
The sidewall fan/powered vent cap must be interlocked with the units control system to start the fan on a call for
heat and prove fan operation before the water heater fires. Plug-in and terminal strip connections are provided on
the unit for easy connection of the factory supplied vent kit and control package for the sidewall vent fan. See the
installation instructions provided with the vent kit.
Sidewall vent termination clearances and location
Locate the bottom of the vent terminal at least 12 inches (30cm) above grade and above normal snow levels. Locate
the bottom of the vent terminal at least 7 feet (2.13m) above grade when located adjacent to public walkways. Do
not terminate directly above a public walkway.
Do not terminate the venting system in a window well, stairwell, alcove, courtyard, or other recessed area. Do not
terminate the venting system below grade.
Locate vent termination at least 3 feet (0.91m) from an inside corner of an L-shaped structure.
Provide a minimum clearance of 4 feet (1.2m) horizontally from electric meters, gas meters, regulators, and relief
equipment. Never locate vent cap above or below electric meters, gas meters, regulators, and relief equipment unless
a 4 foot (1.2m) horizontal clearance is maintained.
- see page 15.
Before installing a venting system, follow all requirements found in the General Venting
section.
Installation & Operation Manual
23