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VII. Venting (continued)
H. Vent and Combustion Air Terminations
1. Vent Piping
a. Install fire stops where vent passes through
floors, ceilings or framed walls. The fire stop
must close the opening between the vent pipe
and the structure.
b. Whenever possible, install vent straight through
the roof.
c. Size roof opening to maintain minimum clearance
of 1 in. (25 mm) from combustible materials.
d. Extend vent pipe to maintain minimum vertical
distance for expected snow accumulation.
Provide brace as required.
e. Install storm collar on vent pipe immediately
above flashing. Apply Dow Corning Silastic 732
RTV Sealant or equivalent between vent pipe
and storm collar to provide weather-tight seal.
2. Combustion Air Piping
a. If possible, locate combustion air termination in
the same roof location as the vent termination
to prevent nuisance shutdowns. Alternatively,
this appliance may be installed with a vertical
roof vent terminal and sidewall combustion air
terminal.
b. Size roof opening to allow easy insertion
of combustion air piping and allow proper
installation of flashing and storm collar to prevent
moisture from entering the structure.
c. Use appropriately designed vent flash when
passing through roofs. Follow flashing
manufacturers' instructions for installation.
d. Extend combustion air pipe to maintain minimum
vertical and horizontal distance of 12 in (300
mm) from roof surface or from the maximum
snow level.
CAUTION
CAUTION
Intermittent shutdowns can occur when the vent
terminals are subject to winds above 40 mph.
The required spacing between vent and com-
bustion air terminals is to prevent flue gas recir-
culation. Recirculation of flue gas products into
the combustion air supply can cause damage to
property or the appliance.
24
NOTICE
NOTICE
Methods of securing and sealing terminals to
the outside wall must not restrain the thermal
expansion of the vent pipe.
Exterior run should be included in equivalent
vent/combustion air lengths.
Vertical Venting and combustion air roof
penetrations (where applicable) require the
use of roof flashing and storm collar, which
are not supplied with appliance, to prevent
moisture from entering the structure.
Examine all components for possible shipping
damage prior to installation.
All condensate that forms in vent must be able
to drain back to the heat exchager or a boot tee
with a drain.
The venting system must be free to expand and
contract and must be supported in accordance
with installation instructions included by the
original component manufacturers, whenever
applicable. Polypropylene pipe sections must
not be fully inserted. Leave 1/4 to 5/8 in. (6
mm to 16 mm) per joint to allow for thermal
expansion.
WARNING
WARNING
Failure to vent this appliance in accordance with
these instructions could cause products of com-
bustion to enter the building resulting in severe
property damage, personal injury or death.
Do not locate vent termination under a deck, or
where exposed to prevailing winds.
Do not locate combustion air termination where
volatile vapors or other chemicals are present.
Severe corrosion and failure will result.
Do not interchange vent systems or materials
unless otherwise specified.
Do not apply thermal insulation to vent pipe or
fittings.
Do not use a barometric damper or draft hood
with this appliance.
AMP 400-1000L I&O Manual
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