035-20499-001 Rev. B (1004)
Unitary Products Group
13
EXTERNAL HORIZONTAL VENT DRAIN
When installing the furnace with a horizontal vent configuration it will be
necessary to install an external drain tee in the horizontal portion of the
vent pipe. The drain tee should be as close as possible to the furnace.
This is recommended to prevent accumulation of excess condensate in
the inducer blower or vent pipe during operational cycles. Refer to Fig-
ure 17 for recommended external vent drain configuration and connec-
tions.
COMBUSTION AIR SUPPLY
All installations must comply with Section 5.3, Air for Combustion and
Ventilation of the National Fuel Gas Code, ANSI Z223.1 or Sections
7.2, 7.3 or 7.4 of CAN/CGA B149.1 or .2 Installation Code - latest edi-
tions.
This furnace is certified to be installed with one of three possible com-
bustion air intake configurations.
1.
OUTDOOR COMBUSTION AIR:
This is a sealed combustion air
configuration where the combustion air is supplied through a PVC
or ABS pipe that is connected to the PVC coupling attached to the
burner box and is terminated in the same atmospheric zone as the
vent. This type of installation is approved on all models. Refer to
Figure 18.
2.
AMBIENT COMBUSTION AIR:
Combustion air is supplied from
the area surrounding the furnace through vents or knockouts in the
furnace casing. The combustion air and the vent pipes are not ter-
minated in the same atmospheric zone. Refer to Figure 13 for vent
terminations. Refer to “AIR SOURCE FROM INSIDE THE BUILD-
ING” and “VENT AND SUPPLY AIR SAFETY CHECK” for proper
installation. Refer to Figure 19.
3.
VENTILATED COMBUSTION AIR:
Combustion air is supplied
through a PVC or ABS pipe that is connected to the PVC coupling
attached to the burner box and is terminated in a ventilated attic or
crawl space. The combustion air and the vent pipes are not termi-
nated in the same atmospheric zone. Refer to Figure 21 for attic
and crawl space termination. Only the combustion air intake may
terminate in the attic. The vent must terminate outside.
Outdoor Combustion Air
Combustion Air Intake/Vent Connections
This installation requires combustion air to be brought in from outdoors.
This requires a properly sized pipe (Shown in Figure 18) that will bring
air in from the outdoors to the furnace combustion air intake collar on
the burner box. The second pipe (Shown in Figure 18) is the furnace
vent pipe.
The combustion air intake pipe should be located either through the
wall (horizontal or side vent) or through the roof (vertical vent). Care
should be taken to locate side vented systems where trees or shrubs
will not block or restrict supply air from entering the terminal.
Also, the terminal assembly should be located as far as possible from a
swimming pool or a location where swimming pool chemicals might be
stored. Be sure the terminal assembly follows the outdoor clearances
listed in Section #1 “Outdoor Air Contaminants.”
FIGURE 15:
Double Horizontal Sealed Combustion Air and Vent
Termination
FIGURE 16:
Double Vertical Sealed Combustion Air and Vent
Termination
FIGURE 17:
External Horizontal Vent Drain
VENT
2”
COMBUSTION AIR
6”
VENT PIPE
FIELD SUPPLIED
EXTERNAL VENT
DRAIN
3” MINIMUM
LOOP DIAMETER
MANUFACTURER
SUPPLIED PVC
WYE AND VENT DRAIN
VENT TRAP
VENT DRAIN
TEE
FIGURE 18:
Sealed Combustion Air Intake Connection and Vent
Connection
CONNECTS TO
COLLAR ON TOP
OF BURNER BOX
VENT PIPE CEMENTS
INTO SOCKET JUST
ABOVE TOP PANEL
