Lennox EL296UHE Installation Instructions Manual page 16

Horizontal Installation Offset Requirements
Exhaust Pipe
12" Max.
Horizontal
Gas Furnace
NOTE - All horizontal runs of exhaust pipe must slope back to­
ward unit. A minimum of 1/4" (6mm) drop for each 12" (305mm)
of horizontal run is mandatory for drainage.
NOTE - Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE - Exhaust piping should be checked carefully to make
sure there are no sags or low spots.
FIGURE 22
TABLE 3
MINIMUM VENT PIPE LENGTHS
EL296UHE
MODEL
045, 070, 090, 110, 135
*Any approved termination may be added to the minimum length listed.
12" Min.
MIN. VENT LENGTH*
15 ft. or
5 ft. plus 2 elbows or
10 ft. plus 1 elbow
Page 16
Use the following steps to correctly size vent pipe diameter.
Piping Size Process
What is the
furnace capacity?
1
045, 070, 090,
110 or 135?
Which style termination
being used?
2
Standard or concentric?
See table 4.
Which needs
most elbows?
3
Intake or
exhaust?
How many elbows?
Count all elbows inside
4
and outside house.
Desired pipe size?
5
2", 2-1/2", 3"
What is the altitude of
6
the furnace installation?
Use table 5 or 6 to find
max intake or exhaust pipe
7
length. Includes all vent
pipe and elbows inside
and outside the house.
FIGURE 23
IMPORTANT
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups
and may block the terminations.