Bryant 350MAV Installation, Start-Up, And Operating Instructions Manual page 23

NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
AIR
FLOW
COMBUSTION- COMBUSTION-
AIR AIR
VENT
VENT
UPFLOW
COMBUSTION-
AIR
VENT
AIR
FLOW
HORIZONTAL-LEFT DISCHARGE
Fig. 27—Combustion-Air and Vent Pipe Connections
WARNING: Solvent cements are combustible. Keep
away from heat, sparks, and open flame. Use only in
well-ventilated areas. Avoid breathing in vapor or allow-
ing contact with skin or eyes. Failure to follow this
warning could result in fire, property damage, personal
injury, or death.
WARNING: All combustion-air and vent pipes must be
airtight and watertight. Pipes must also terminate exactly
as shown in Fig. 30, 31, 32, 33, or 34. Failure to follow
this warning could result in property damage, personal
injury, or death.
NOTE: The minimum combustion-air and vent pipe length (each)
for these furnaces is 5 ft. Short pipe lengths (5-8 ft) may discharge
water droplets. These droplets may be undesirable, and a 12-in.
minimum offset pipe section is recommended, as shown in Fig. 28,
to reduce excessive droplets from exiting vent pipe outlet.
COMBUSTION-AIR AND VENT PIPE DIAMETER
Determine combustion-air and vent pipe diameter.
1. Using Table 6, individually determine the combustion-air
and vent pipe diameters. Pick the larger of these 2 pipe
diameters and use this diameter for both combustion-air and
vent pipes.
2. When installing vent systems of short pipe length, use the
smallest allowable pipe diameter. Do not use pipe size
greater than required or incomplete combustion, flame
disturbance, or flame sense lockout may occur.
NOTE: Do not count elbows or pipe sections in terminations or
within furnace. See shaded areas in Fig. 30, 31, 32, 33, and 34.
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
VENT
VENT
COMBUSTION- COMBUSTION-
AIR AIR
AIR
FLOW
DOWNFLOW
COMBUSTION-
AIR
VENT
AIR
FLOW
HORIZONTAL-RIGHT DISCHARGE
A96187
EXAMPLE: An 036080 size furnace located in Indianapo-
lis, elevation 650 ft above sea level, could be installed in an
application requiring 3 elbows and 32 ft of vent pipe, along
with 5 elbows and 34 ft of combustion-air pipe. Table 6
indicates this application would allow a 2-in. diameter vent
pipe, but require a 2-1/2 in. diameter combustion air pipe
(2-in. pipe is good for 35 ft with 3 elbows, but only 30 ft
with 5 elbows). Therefore, 2-1/2 in. diameter pipe must be
used for both vent and combustion-air pipes since larger
required diameter must always be used for both pipes. If
same installation were in Albuquerque, elevation 5250 ft
above sea level, installation would require 2-1/2 in. vent
pipe and combustion-air pipe. At 5001- to 6000-ft eleva-
tion, 2-in. pipe is only good for 17 ft with 5 elbows, and
2-1/2 in. pipe is good for 70 ft with 5 elbows.
COMBUSTION-AIR AND VENT PIPE ATTACHMENT
NOTE: All pipe joints must be watertight except attachment of
combustion-air pipe to inlet housing connection, since it may be
necessary to remove pipe for servicing.
1. Attach combustion-air pipe as follows:
a. Determine location of combustion-air intake pipe con-
nection to combustion-air intake housing as shown in
Fig. 27 for application.
b. Reposition combustion-air intake housing plug fitting in
appropriate unused intake housing connection.
c. If required, insert perforated disk assembly (factory-
supplied in loose parts bag) in intake housing where
combustion-air intake pipe will be connected. If half disk
set is required, install with shoulder of disk against stop
in combustion-air inlet.
d. Install pipe support (factory-supplied in loose parts bag)
into selected furnace casing combustion-air pipe hole.
Pipe support should be positioned at bottom of casing
hole.
e. Insert 2-in. diameter pipe into intake housing.
NOTE: A 2-in. diameter pipe must be used within the furnace
casing. Make all pipe diameter transitions outside furnace casing.
→
f. Install casing hole filler cap (factory-supplied in loose
parts bag) in unused combustion-air pipe casing hold.
g. Drill a 1/8-in. hole in 2-in. combustion-air pipe using
hole in intake housing as a guide.
h. Install a field-supplied No. 6 or No. 8 sheet metal screw
into combustion-air pipe.
NOTE: DO NOT OVERTIGHTEN SCREW. Breakage to intake
housing or fitting may cause air leakage to occur.
NOTE: Do not attach combustion-air intake pipe permanently to
combustion-air intake housing since it may be necessary to remove
pipe for service of ignitor or flame sensor.
COMBUSTION-AIR INTAKE HOUSING PLUG FITTING
The combustion-air intake plug fitting must be installed in unused
combustion-air intake housing. This fitting must be attached by
using RTV sealant, or by drilling a 1/8-in. hole in fitting, using
hole in intake housing as a guide. Install a field-supplied No. 6 or
No. 8 sheet metal screw.
NOTE: DO NOT OVERTIGHTEN SCREW. Breakage to intake
housing or fitting may cause air leakage to occur.
A plugged drain connection has been provided on this fitting for
use when moisture is found in combustion-air intake pipe and
combustion box.
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