Vent Piping Guidelines
NOTE - Lennox has approved the use of DuraVent® and 
Centrotherm  manufactured  vent  pipe  and  terminations 
as  an  option  to  PVC.  When  using  the  PolyPro
®
  by  Du-
raVent  or  InnoFlue
®
  by  Centrotherm  venting  system  the 
vent  pipe  requirements  stated  in  the  unit  installation  in-
struction – minimum & maximum vent lengths, termination 
clearances, etc. – apply and must be followed. Follow the 
instructions provided with PoyPro by DuraVent and Inno-
Flue by Centrotherm venting system for assembly or if re-
quirements are more restrictive. The PolyPro by Duravent 
and  InnoFlue  by  Centrotherm  venting  system  must  also 
follow the uninsulated and unconditioned space criteria 
listed in TABLE 15 .
The EL196UHE can be installed as either a Non-Direct 
Vent or a Direct Vent gas central furnace.
NOTE - In  Non-Direct  Vent  installations,  combustion  air 
is taken from indoors and ue gases are discharged out-
doors. In Direct Vent installations, combustion air is taken 
from outdoors and ue gases are discharged outdoors.
  
      
-
-
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
NOTE - Exhaust pipe MUST be glued to furnace exhaust fitting,
unless the optional glueless vent adapter kit 17H92 is used..
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.
Exhaust Pipe
Horizontal
Gas Furnace
12” Min.
12” Max.
FIGURE 24 
TABLE 12 
 
-
Piping Size Process
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
the house.
What is the altitude of
the furnace installation?
7
What is the
furnace capacity?
 
FIGURE 25