Venting, Vent installation considerations – A.O. Smith 3400 User Manual
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PVC/CPVC INSTALLATION:
Installation must comply with local requirements and with the
National Fuel Gas Code, ANSI Z223.1 for U.S. installations or
CSA B149.1 for Canadian installations.
Refer to Table 12 on Page 37 for PVC/CPVC piping materials.
PVC/CPVC Installation requires the use of factory supplied
PVC/CPVC adapters.
All PVC vent pipes must be glued, properly supported, and
the exhaust must be pitched a minimum of a 1/4 inch per foot
back to the boiler (to allow drainage of condensate).
This boiler requires a special venting system. Use only the
vent materials, primer, and cement specified in this manual
to make the vent connections. Failure to follow this warning
could result in fire, personal injury, or death.
NOTE: Make sure that for PVC venting installation, the
first 10 feet (3 m) of vent must be CPVC and the set point
temperature of the boiler must not exceed 200 °F.
STAINLESS STEEL INSTALLATION:
The factory supplied polypropylene vent kit will not adapt to
stainless steel installation. For using the boiler with stainless
steel, contact factory or pre-order the unit with stainless steel kit.
Installations must comply with applicable national, state, and
local codes. Stainless steel vent systems must be listed as a UL-
1738 approved system for the United States and a ULC-S636
approved system for Canada.
Installation of the approved AL 29-4C stainless steel venting
material should adhere to the stainless steel vent manufacturer’s
installation instructions supplied with the vent system.
Refer to Table 13 and Table 14 on Page 37 for air intake and vent
pipe sizes.
AIR INTAKE/VENT CONNECTIONS
1. Air Intake Adapter: Provides an inlet for combustion air
directly to the unit from outdoors.
2. Vent Outlet: Provides an outlet for combustion gases to
outdoors.
VENTING SYSTEM
This boiler may be installed in six separate orientations
depending on the require ments of the building and
the appliance. The installer must decide which method is most
appro priate for each installation. These orientations are:
1. Vertical Termination - vertical vent termi na tion through
un-enclosed or en closed areas with roof penetration, see
2. Through-the-Wall Termination (TWT) - hori zontal vent
termination directly through an outside wall, see Figure 25
on Page 29.
3. Horizontal Direct Vent - using TWT to exhaust flue
prod ucts and PVC piping to bring combus tion air to the boiler
from the outside. See Figure 26 on Page 30 and Figure 29
on Page 31.
4. Vertical Direct Vent - using a vertical vent termination to
exhaust flue products and PVC piping to bring combustion
air to the boiler from outside, see Figure 27 on Page 30 and
VENTING
VENT INSTALLATION CONSIDERATIONS
This boiler is a category IV appliance that can be vented using
room air for intake combustion air, or direct vented so that all
intake air for combustion comes from the outside through a
sealed pipe. When installing this boiler as direct vent, use the
recommended terminations in this section, refer to Page 28 till
Page 31.
In cold climates any water vapor remaining in the flue gases will
condense into a cloud of vapor at the point where the vent system
exits the building. Special consideration is recommended, before
locating the vent termination near walkways, windows and
building entrances.
Direct venting into dead spaces such as alleys, atriums, and
inside corners can cause recirculation of flue gases. Recirculation
of flue gases will cause sooting, premature failure of the heat
exchanger, and icing of the combustion air intake during severe
cold weather. To prevent the recirculation of flue gases, maintain
as much distance as possible between the combustion air
intake and the exhaust vent terminal. Due to large volumes of
flue gases, multiple boiler applications also require additional
distance between the intake and the exhaust terminals.
This boiler must be vented with Polypropylene, PVC/CPVC or
an UL approved AL 29-4C Stainless Steel venting material which
are explained in the following pages. Vent sizing, installation and
termination should be in accordance with this instruction manual.
All electrical power and gas must be turned off prior to any
installation of the venting system.
GENERAL VENT INSTALLATION PROCEDURE
Prior to beginning the installation of the vent system, determine
and obtain all parts required for the installation. Proper operation
of the boiler and venting system is dependent upon use of all
specified parts and installation techniques; both safety and
proper performance of the system may suffer if instructions are
not followed.
POLYPROPYLENE INSTALLATION:
All XB Boilers are shipped with Polypropylene venting kits
out of the factory. These kits are in separate cartons along
with the boiler shipment. They must be assembled and
installed on the boiler as shown in Figure 22 & Figure 23.
Using Centrocerin is recommended as an assembly lube
for venting. Application of Centrocerin resists movement
between the vent legths and fittings.The vent pipes must also
be properly suppported. The kit also includes a PVC/CPVC
adapter, which can be discarded and will only be required
for PVC/CPVC vent installations. A condensate draft is also
supplied with the venting kit and needs to be piped separately
in the field.