Carrier 58MXA Operating And Instruction Manual page 21

Table 4—Combustion-Air and Vent Pipe
Termination Clearances
LOCATION
Above grade level or above antici-
pated snow depth
Dryer vent
From plumbing vent stack
From any mechanical fresh air intake
For furnaces with an input capacity
less than 100,000 Btuh—from any
non-mechanical air supply (windows
or doors which can be opened) or
combustion-air opening
For furnaces with an input capacity
greater than 100,000 Btuh—from any
non-mechanical air supply (windows
or doors which can be opened) or
combustion-air opening
From service regulator vent, electric
and gas meters, and relief equipment
Above grade when adjacent to public
walkway
* Horizontal distance.
† 18 in. above roof surface in Canada.
‡ 36 in. to electric meter in Canada only.
NOTES:
1. If installing 2 adjacent 58MXA Furnaces, refer to Multiventing and Vent
Terminations section for proper vent configurations.
2. When locating combustion-air and vent terminations, consideration must be
given to prevailing winds, location, and other conditions which may cause
recirculation of the appliance's own flue products or the flue products of
adjacent vents. Recirculation can cause poor combustion, inlet condensate
problems, and accelerated corrosion of heat exchangers.
Furnace combustion-air and vent pipe connections must be at-
tached as shown in Fig. 28. Combustion-air intake plug fitting and
inducer housing alternate vent cap may need to be relocated in
some applications.
NOTE: Slope combustion-air and vent pipes a minimum of 1/4
in. per linear ft with no sags between hangers.
When combustion-air pipe is installed above a suspended
ceiling, pipe must be insulated with 3/8-in. thick Armaflex-
type insulation. Combustion-air pipe should also be insulated
when it passes through warm, humid space.
When vent pipe is exposed to temperatures below freezing,
such as when it passes through an unheated space or when a
chimney is used as a raceway, pipe must be insulated as
shown in Table 6 with Armaflex-type insulation.
Combustion air must not be taken from inside structure
because inside air is frequently contaminated by halogens,
which include fluorides, chlorides, bromides, and iodides.
These elements are found in aerosols, detergents, bleaches,
cleaning solvents, salts, air fresheners, adhesives, paint, and
other household products. Locate combustion-air inlet as far
as possible from swimming pool and swimming pool pump
house.
Excessive exposure to contaminated combustion air will
result in safety and performance related problems.
CLEARANCE (FT)
U.S.A. Canada
1 1†
3 3
3 3
1 6
1 1
1 3
4* 6‡
7 7
→
→
21
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. 28—Combustion-Air and Vent Pipe Connec-
tions
Solvent cements are combustible. Keep away from heat,
sparks, and open flame. Use only in well-ventilated areas.
Avoid breathing in vapor or allowing contact with skin or
eyes. Failure to follow this warning could result in fire,
property damage, personal injury, or death.
All combustion-air and vent pipes must be airtight and
watertight. Pipes must also terminate exactly as shown in Fig.
31, 32, 33, 34, or 35. 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. 29,
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 5, 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. 31, 32, 33, 34, and 35.
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
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