Page 76
Horizontal furnace (FIGURE  50)  -  In  horizontal  fur-
nace  applications  the  eld  provided  vent  must  be  a 
minimum  4”  to  a  maximum  5”  length  above  the  con-
densate drain outlet connection. Any length above 5” 
may result in a ooded heat exchanger if the combined 
primary drain line were to become restricted.
NOTE - In horizontal applications it is recommended 
to install a secondary drain pan underneath the unit 
and trap assembly.
NOTE - Appropriately sized tubing and barbed tting 
may  be  used  for  condensate  drain.  Attach  to  the 
drain on the trap using a hose clamp. See FIGURE 
44.
Field Provided Drain Components
Tubing
Hose Clamp
Barbed Fitting
Elbow
FIGURE 44 
 CAUTION
Do not use copper tubing or existing copper 
condensate lines for drain line.
6 -  If  unit  will  be  started  immediately  upon  completion 
of installation, prime trap per procedure outlined in 
Unit Start-Up section. Condensate line must slope 
downward away from the trap to drain. If drain level 
is above condensate trap, condensate pump must 
be used.
Condensate drain line should be routed within the con-
ditioned  space  to  avoid  freezing  of  condensate  and 
blockage  of  drain  line.  If  this  is  not  possible,  a  heat 
cable kit may be used on the condensate trap and line. 
Heating  cable  kit  is  available  from  Lennox  in  various 
lengths; 6 ft. (1.8m) - kit no. 26K68; 24 ft. (7.3m) - kit 
no. 26K69; and 50 ft. (15.2m) - kit no. 26K70.
(Unit shownin upflow position withremote trap)
*5’ max.
To  Drain
PVCPipeOnly
FieldProvidedVent
Min.1” Above Condensate
Drain
Connection
1”
Min.
Trap CanBeInstalleda
Maximum 5’ From Furnac
e
2” Max.
CONDENSATE TRAP LOCATIONS
*Piping from furnace must slope down a
minimum 1/4” per ft. toward trap
FIGURE 45 
Furnace With Evaporator
Coil Using A Separate Drain
Condensate
Drain
Connection
Field Provided Vent
(1” min. 2” max. above
condensate connection)
Evaporator drain
line required
(Trap at coil is optional)
FIGURE 46