Lennox G43UF SERIES Unit Information page 26

General Guidelines for Vent Terminations for Non-Direct
Vent Installations.
In Non-Direct Vent applications, combustion air is taken
from indoors and the flue gases are discharged to the out-
doors. The G43UF is then classified as a non-direct vent,
Category IV gas furnace. In Non-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 cur-
rent CSA−B149 Natural Gas and Propane Installation
Codes in Canada for details.
Position termination end according to location given in fig-
ure 23. In addition, position termination end so it is free
from any obstructions and above the level of snow accu-
mulation (where applicable). The termination should be at
least 12 inches (305mm) from any opening through which
flue products could enter the building.
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 − If winter design temperature is below 32°F (0°C),
exhaust piping should be insulated with 1/2" (13mm), Ar-
maflex or equivalent when run through unheated space.
Do not leave any surface area of exhaust pipe open to out-
side air; exterior 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 neces-
sary. 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.
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 kit is avail-
able from Lennox. See Condensate Piping section for part
numbers.
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze−ups and
may block the terminations.
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
(305mm).
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IMPORTANT
IMPORTANT