Lennox SLP98UHV Installation Instructions Manual page 26

IMPORTANT
When combining the furnace and evaporator
coil drains together, the A/C condensate drain
outlet must be vented to relieve pressure in or-
der for the furnace pressure switch to operate
properly.
Condensate Trap With Optional Overflow Switch
From Evaporator Coil
HorizontalFurnace4" Min. to 5" Max.above
Optional
FIGURE 40
Evaporator
Drain Pan
Piping from furnace and evaporator coil must slope down a minimum 1/4" per ft. toward trap
condensatedrain connection)
FurnaceCondensate
Drain Connection
SLP98UHV with Evaporator Coil Using a Common Drain
(Unit shown in horizontal left−hand discharge position)
Coil
Condensat e Drai n
Connection
SLP98UHV with Evaporator
Coil Using a Common Drain
(1" min. to 2" Max.above
condensatedrain connection)
Condensate
Drain Connection
4"min
5"max
5' max.
PVC Pipe Only
FIGURE 42
Page 26
Evaporator drain
line required
FIGURE 41
(4" min. to 5" Max.above
condensatedrain connection)