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CAUTION: When condensate traps are installed,
condensate must be routed to an appropriate
container for neutralization before disposal, as
required by local codes.
WARNING: Contact the manufacturer of the vent
material if there is any question about the appliance
categorization and suitability of a vent material for
application on a Category III or IV vent system.
Using improper venting materials can result in
personal injury, death or property damage.
Support of Vent Stack
The weight of the vent stack or chimney must not rest
on the heater vent connection. Support must be pro-
vided in compliance with applicable codes. The vent
should also be installed to maintain proper clearances
from combustible materials.
Use insulated vent pipe spacers where the vent pass-
es through combustible roofs and walls.
Vent Terminal Location
NOTE: During winter months check the vent cap
and make sure no blockage occurs from build-up of
snow or ice.
Combustion
Air Supply
From Inside Building
(Non-Direct Venting)
From Outside Building
(Direct Venting)
Exhaust
Heater Venting
Configuration
Vertical Natural
Draft Venting
Horizontal Through-
the-Wall Venting
Vertical Natural
Draft Venting
Horizontal Through-
the-Wall Venting
Table L: Venting Category Requirements
26
1. Condensate can freeze on the vent cap. Frozen
condensate on the vent cap can result in a blocked
flue condition.
2. Give special attention to the location of the vent
termination to avoid possibility of property dam-
age or personal injury.
3. Gases may form a white vapor plume in winter.
The plume could obstruct a window view if the ter-
mination is installed near windows.
4. Prevailing winds, in combination with below-freez-
ing
temperatures,
condensate and water/ice build-up on buildings,
plants or roofs.
5. The bottom of the vent terminal and the air intake
shall be located at least 12 in. above grade, includ-
ing normal snow line.
6. Un-insulated single-wall metal vent pipe shall not
be used outdoors in cold climates for venting gas-
fired equipment.
7. Through-the-wall vents for Category II and IV
appliances and non-categorized condensing appli-
ances shall not terminate over public walkways or
over an area where condensate or vapor could
create a nuisance or hazard or could be detrimen-
tal to the operation of regulators, relief valves, or
other equipment. Where local experience indi-
cates that condensate is a problem with Category
I and III appliances, this provision shall also apply.
Certified
Category
Materials
I
"B" Vent
Stainless Steel
III
(Gas Tight)
I
"B" Vent
Stainless Steel
III
(Gas Tight)
can
cause
freezing
Combustion Air
Inlet Material
Galvanized Steel
PVC
ABS
CPVC
of
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