Page 18
Horizontal Installation Offset Requirements
NOTE - Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE -
ward unit. A minimum of 1/4” (6mm) drop for each 12” (305mm)
of horizontal run is mandatory for drainage.
NOTE - Exhaust piping should be checked carefully to make
sure there are no sags or low spots.
12” ma x
of straight pip
e
Exhaust Pipe
12”Min .
Horizontal
Gas Furnace
FIGURE 23
TABLE 4
MINIMUM VENT PIPE LENGTHS
ML296UHV MODEL MIN. VENT LENGTH*
045, 070, 090, 110
15 ft. or 5 ft plus 2 elbows or
10 ft plus 1 elbow
*Any approved termination may be added to the minimum length
listed.
IMPORTANT
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.
Use the following steps to correctly size vent pipe diam-
eter.
1
2
3
4
5
6
Which style termination
being used?
Standard or
concentric?.
Which needs
most elbows?
Intake or
exhaust?
How many elbows?
Count all elbows inside
and outside house.
Desired pipe size?
Find max intake or
exhaust pipe length.
Includes all vent pipe and
elbows inside and outside
What is the altitude of
the furnace installation?
7
What is the
furnace capacity?
FIGURE 24
NOTE - Lennox oers a glueless vent adapter kit 17H92
as an option for exhaust exiting at the furnace top cap
coupling.
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