COMFORT-AIRE Century GUH96T045B3M, Service Manual

508183-01

Issue 2114

Page 37 of 52

Condensate Piping

This  unit  is  designed  for  either  right-  or  left-side  exit  of 

condensate  piping  in  upflow  applications.  In  horizontal 

applications, the condensate trap must extend below the 

unit. An 8” service clearance is required for the condensate 

trap. Refer to Figure 40 and Figure 41 for condensate trap 

locations.  Figure  48  and  Figure  49  show  trap  assembly 

using 1/2” PVC or 3/4” PVC.

NOTE: 

If necessary the condensate trap may be installed 

up to 5’ away from the furnace. Use PVC pipe to connect 

trap to furnace condensate outlet. Piping from furnace 

must slope down a minimum of 1/4” per ft. toward trap.

Figure 40. Condensate Trap and Plug Locations 

(unit shown in upflow position)

NOTE:

In upflow applications where side return air filter is installed 

on same side as the condensate trap, filter rack 

MUST

 be installed 

beyond condensate trap or trap must be relocated to avoid 

interference.

(Unit shown in upflow position with remote trap)

*5’ max.

To Drain

PVCPipeOnly

FieldProvidedVent

Min. 1” AboveCondensate

DrainConnection

1” Min.

2” Max.

Trap can be installed a

maximum 5' from furnace

*Piping from furnace must slope down a minimum of

1/4” per ft. toward trap.

Figure 41. Condensate Trap Locations

1.

Determine which side condensate piping will exit the

unit, location of trap, field-provided fittings and length

of PVC pipe required to reach available drain.

2.

Use  a  large  flat  head  screw  driver  or  a  1/2”  drive

socket  extension  and  remove  plug  (Figure  40)  from

the  cold  end  header  box  at  the  appropriate  location

on the side of the unit. Install provided 3/4 NPT street

elbow fitting into cold end header box. Use Teflon tape

or appropriate pipe dope.

NOTE: 

Cold  end  header  box  drain  plugs  are  factory

installed.  Check  the  unused  plug  for  tightness  to

prevent leakage.

3.

Install the cap over the clean out opening at the base

of  the  trap.  Secure  with  clamp.  See  Figure  48  and

Figure 49.

4.

Install drain trap using appropriate PVC fittings, glue

all  joints.  Glue  the  provided  drain  trap  as  shown  in

Figure 48 and Figure 49. Route the condensate line to

an open drain. Condensate line must maintain a 1/4”

downward slope from the furnace to the drain.

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.

 IMPORTANT

5.

Figure  43  and  Figure  44  show  the  furnace  and

evaporator  coil  using  a  separate  drain.  If  necessary

the condensate line from the furnace and evaporator

coil can drain together. See Figure 46 through Figure

47.

Upflow  furnace  (Figure  43)  - 

In  upflow  furnace

applications the field provided vent must be a minimum

1” to a maximum 2” length above the condensate drain

outlet connection. Any length above 2” may result in a

flooded heat exchanger if the combined primary drain

line were to become restricted.

Horizontal furnace (Figure 44) - 

In horizontal furnace

applications the field provided vent must be a minimum

4” to a maximum 5” length above the condensate drain

outlet connection. Any length above 5” may result in a

flooded 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  fitting

may be used for condensate drain. Attach to the drain

on the trap using a hose clamp. See Figure 42.