Carrier 58MXA Installation, Start-Up, And Operating Instructions Manual page 21

Table 4–Combustion-Air and Vent Pipe
Termination Clearances
LOCATION
Above grade level or above
anticipated snow depth
Dryer vent
From plumbing vent stack
From any mechanical fresh air
intake
For furnaces with an input ca-
pacity 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 ca-
pacity greater than 100,000
Btuh–from any non-
mechanical air supply (win-
dows 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.
Fig. 28—Combustion-Air and Vent Pipe
Connections
CLEARANCE (FT)
U.S.A. Canada
1 1†
3 3
3 3
1 6
1 1
1 3
4* 6‡
7 7
A93083
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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.
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 horizontal 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, determine preliminary combustion-air pipe
diameter.
2. Using Table 5, determine preliminary vent pipe diameter.
3. Use largest diameter pipe determined in 1. and 2. above for
both pipes.
NOTE: Do not count elbows or pipe sections in terminations or
within furnace. See shaded areas in Fig. 31, 32, 33, 34, and 35.
EXAMPLE:
An 080-12 size furnace located in Indianapolis, 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 5 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 elevation, 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: