Table M: Category III Horizontal and Direct Venting
*Subtract 10 ft per elbow. Max. 3 elbows.
Maximum combustion air duct length terminated at 100 equivalent ft.
WARNING:
No substitutions of flue pipe or vent
cap material are allowed. Such substitutions would
jeopardize the safety and health of inhabitants.
Model
No.
Certified
Venting
Material
Vent
Size
Maximum
Equivalent
Vent Length*
Combustion
Air
Intake Pipe
Material
Air Inlet Max. Length*
6”
8”
10”
12”
399B
Category III
6”
70’Room Air
40’ Ducted
Combustion Air
Galvanized
Steel,
PVC, ABS,
CPVC
100’
499B
75’
100’
649B
8”
40’
749B
899B
30’
80’
989B
10”
75’
100’
1259B
12”
1529B
1799B
14”
40’
75’
1999B
2069B
2339B
16”
The vent must be installed to prevent flue gas leakage.
Care must be taken during assembly to ensure that all
joints are sealed properly and are airtight. The vent
must be installed to prevent the potential accumulation
of condensate in the vent pipes. It is required that:
1.
The vent must be installed with a slight downward
slope of not more than 1/4 inch per foot of hori-
zontal run to the vent terminal.
2.
The vent must be insulated through the length of
the horizontal run.
For installations in extremely cold climate, it is re-
quired that:
1.
The vent must be installed with a slight upward
slope of not more than 1/4 inch per foot of hori-
zontal run to the vent terminal. In this case, an
approved condensate trap must be installed per
applicable codes.
2.
The vent must be insulated through the length of
the horizontal run.
Termination
The flue direct vent cap MUST be mounted on the ex-
terior of the building. The direct vent cap cannot be
installed in a well or below grade. The direct vent cap
must be installed at least 1 ft above ground level and
above normal snow levels. The Raypak-approved
stainless steel flue direct vent cap must be used (sales
order option D-15).
Use only the special gas vent pipes listed for use with
Category III gas burning heaters, such as the AL29-4C
stainless steel vents offered by Heat Fab Inc. (800-
772-0739), Protech System, Inc. (800-766-3473),
Z-Flex (800-654-5600) or American Metal Products
(800-423-4270). Pipe joints must be positively sealed.
Follow the vent manufacturer’s installation instructions
carefully.
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