Allied A97USMV, Installation Instructions Manual

Page: 20 / 78

506887-01 Page 20 of 78 Issue 1213
Table 6
Maximum Allowable Vent pipe Length without Insulation in Unconditioned Space for Winter Design
Temperatures Modulating High Efficiency Furnace
¹Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
NOTE: Maximum unisulated vent lengths listed cannot exceedd the maximum allowable intake or exhaust vent length listed in Table 5.
General Guidelines for Vent Terminations
In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the outdoors.
This gas furnace is classified as a direct vent, Category IV
gas furnace.
In Direct Vent applications, the vent termination is limited
by local building codes. In the absence of local codes, refer
to the current National Fuel Gas Code ANSI Z223-1/NFPA
54 in U.S.A., and current CSA-B149 Natural Gas and
Propane Installation Codes in Canada for details.
Position termination according to location given in Figure
20. In addition, position termination so it is free from any
obstructions and 12" above the average snow accumulation.
At vent termination, care must be taken to maintain
protective coatings over building materials (prolonged
exposure to exhaust condensate can destroy protective
coatings). It is recommended that the exhaust outlet not
be located within 6 feet (1.8m) of a condensing unit because
the condensate can damage the painted coating.
NOTE: See Table 6 for maximum allowed exhaust pipe
length without insulation in unconditioned space during
winter design temperatures below 32 ° F 0 ° C) . If equired
exhaust pipe should be insulated with 1 / 2 " (13mm) Armaflex
or equivalent . In extreme cold climate areas , 3 / 4 " (19mm)
Armaflex 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 specific
applications
.
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 accorddance 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