Allied A95UH1E - Page 26

507276-03Page 26 of 59 Issue 1621
coatings). It is recommended that the exhaust outlet not be
located within 6 feet (1.8 m) of a condensing unit because
the condensate can damage the painted coating.
NOTE: See Table 7 for maximum allowed exhaust pipe
length without insulation in unconditioned space during
winter design temperatures below 32°F (0°C). If required
exhaust pipe should be insulated with 1/2” (13 mm) Armaex
or equivalent. In extreme cold climate areas, 3/4” (19 mm)
Armaex or equivalent may be necessary. Insulation on
outside runs of exhaust pipe must be painted or wrapped to
protect insulation from deterioration. Exhaust pipe insulation
may not be necessary in some specic applications.
NOTE: During extremely cold temperatures, below
approximately 20° F (6.7° C), units with long runs of vent
pipe through unconditioned space, even when insulated,
may form ice in the exhaust termination that prevents the
unit from operating properly. Longer run times of at least 5
minutes will alleviate most icing problems. Also, a heating
cable may be installed on exhaust piping and termination
to prevent freeze-ups. Heating cable installation kits are
available. See unit specication sheets for part numbers.
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze-ups and may
block the terminations.
IMPORTANT
For Canadian Installations Only:
In accordance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet of
other appliances shall not be less than 12 inches (305
mm).
IMPORTANT
Table 7
Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation
In Unconditioned Space For Winter Design Temperatures Single - Stage High Efciency Furnace
Winter Design Temperatures
1
ºF (ºC)
Vent Pipe
Diameter
Unit Input Size
030/045 070 090 110 135
32 to 21
(0 to -6)
PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP PVC
2
PP
2 in. 18 16 31 28 50 48 30 30 N/A N/A
2-1/2 in. 13 N/A 24 N/A 42 N/A 56 N/A N/A N/A
3 in. 9 9 18 18 35 35 47 47 52 52
20 to 1
(-7 to -17)
2 in. 9 8 18 16 32 29 30 30 N/A N/A
2-1/2 in. 5 N/A 13 N/A 24 N/A 34 N/A N/A N/A
3 in. N/A N/A 8 8 19 19 26 26 30 30
0 to -20
(-18 to -29)
2 in. 5 3 12 10 22 19 30 27 N/A N/A
2-1/2 in. N/A N/A 7 N/A 15 N/A 22 N/A N/A N/A
3 in. N/A N/A N/A N/A 10 10 16 16 18 18
1
Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
2
Poly-Propylene vent pipe (PP) by Duravent and Centrotherm
NOTE - Concentric terminations are the equivalent of 5’ and should be considered when measuring pipe length.
NOTE- Maximum uninsulated vent lengths listed may include the termination (vent pipe exterior to the structure ) and
cannot exceed 5 linear feet or the maximum allowable intake or exhaust vent length listed in table 5 or 6.
NOTE - If insulation is required an unconditioned space, it must be located on the pipe closed to the furnace.