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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 51 
 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.
Coil Using a Common Drain
Field Provided Vent
1” min. 2” max. above
condensate drain.
Evaporator Drain Line
(vent required)
Condensate
Drain Connection
FIGURE 52 
HorizontalFurnace4” Min.to5” Max.above
condensatedrain connection)
FurnaceCondensate
Drain
Connection
From Evaporator Coil
Optional
Condensate Trap With Optional Overflow Switch
FIGURE 53 
 CAUTION
Do not use copper tubing or existing copper condensate 
lines for drain line.