Lennox ELITE Series Installation Instructions Manual page 31

Furnace with Evaporator Coil
Using a Separate Drain
Field Provided Vent
1" min. 2" max. above
condensate drain.
Condensate
Drain Connection
Evaporator Drain Line
(vent required)
Figure 46
IMPORTANT
When combining the furnace and evaporator coil
drains together, the A/C condensate drain outlet must
be vented to relieve pressure in order for the furnace
pressure switch to operate properly.
Furnace with Evaporator
Coil Using a Common Drain
Field Provided Vent
1" min. 2" max. above
condensate drain.
Condensate
Drain Connection
Evaporator Drain Line
(vent required)
Figure 47
Condensate Trap With Optional Overflow Switch
From Evaporator Coil
Drain
Do not use copper tubing or existing copper condensate
lines for drain line.
Page 31
HorizontalFurnace4" Min. to 5" Max.above
condensatedrain connection)
FurnaceCondensate
DrainConnection
Optional
Figure 48
CAUTION