Lennox EL195UH040NE36B Installation Instructions And Use page 18

NOTE - The exhaust collar on all models is sized to ac-
commodate 2" Schedule 40 vent pipe. In horizontal ap-
plications, any transition to exhaust pipe larger than 2"
must be made in vertical runs of the pipe. Therefore a 2"
elbow must be added before the pipe is transitioned to
any size larger than 2". This elbow must be added to the
elbow count used to determine acceptable vent lengths.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.
Horizontal Installation Offset Requirements
Exhaust Pipe
Horizontal
Gas Furnace
12" ma x
of straight pip e
NOTE -
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 24
TABLE 4
MINIMUM VENT PIPE LENGTHS
ML195UH Model
040, -060, -080, 100
*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
Use the following steps to correctly size vent pipe diam-
eter.
Pipe Size Process
1
Which style termination
2
Standard or concentric?
3
How many elbows?
Count all elbows inside
4
and outside house.
5
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.
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.
Page 18
What is the
furnace capacity?
040, 060, 080, or
100?
being used?
See table 3..
Which needs
most elbows?
Intake or
exhaust?
Desired pipe size?
2" or 3"
Figure 25
CAUTION