268882-UIM-A-0407
16
Unitary Products Group
VENTING MULTIPLE UNITS
Only the sealed combustion system can be used for installations requir-
ing more than one furnace in a structure. A separate sealed combustion
air pipe and a separate vent pipe must be installed for each furnace. Do
not connect more than one furnace to a combustion air pipe or a vent
pipe. The combustion air and vent termination must be located as
shown in Figure 19 or 20.
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
Figures 21 & 23.
2.
AMBIENT COMBUSTION AIR (Modular Home Installations
Only:
Combustion air is supplied from the area surrounding the
furnace through the combustion air pipe in the furnace casing. The
combustion air and the vent pipes are not terminated in the same
atmospheric zone. Refer to Figures 22 & 23. Refer to “AIR
SOURCE FROM INSIDE THE BUILDING” and “VENT AND SUP-
PLY AIR SAFETY CHECK” for proper installation.
3.
VENTILATED COMBUSTION AIR (Modular Home Installations
Only:
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 terminated in the same atmospheric
zone. Refer to Figure 24 for crawl space and attic 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 21) that will bring
air in from the outdoors to the furnace combustion air intake collar on
the burner box. The second pipe 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 I “Outdoor Air Contaminants.”
The provided 2” diameter rubber sleeve should be installed on the com-
bustion air pipe sticking through the furnace top, when making connec-
tion with the outdoor combustion air pipe. This, in combination with the
rubber sleeve installed inside the furnace, will facilitate removal of fresh
air pipe in front of the blower housing.
Ambient Combustion Air Supply
(Modular Home Installations
Only
This type installation will draw the air required for combustion from
within the space surrounding the appliance and from areas or rooms
adjacent to the space surrounding the appliance. This may be from
within the space in a non-confined location or it may be brought into the
furnace area from outdoors through permanent openings or ducts. It is
not piped directly into the burner box. A single, properly sized pipe from
the furnace vent connector to the outdoors must be provided. For down-
flow models combustion air is brought into the furnace through the unit
top panel opening. Do not install a pipe into the combustion air pipe at
the top of the furnace. Refer to Figure 22.
FIGURE 19:
Double Horizontal Sealed Combustion Air and Vent
Termination
FIGURE 20:
Double Vertical Sealed Combustion Air and Vent
Termination
VENT
2”
MIN.
COMBUSTION AIR
MIN.
6”
FIGURE 21:
Sealed Combustion Air Intake Connection and Vent
Connection
This type of installation requires that the supply air to the appli-
ance(s) be of a sufficient amount to support all of the appliance(s)
in the area. Operation of a mechanical exhaust, such as an exhaust
fan, kitchen ventilation system, clothes dryer or fireplace may cre-
ate conditions requiring special attention to avoid unsatisfactory
operation of gas appliances. A venting problem or a lack of supply
air will result in a hazardous condition, which can cause the appli-
ance to soot and generate dangerous levels of CARBON MONOX-
IDE, which can lead to serious injury, property damage and / or
death.
2” (5.08 cm)
COMBUSTION
AIR INTAKE
CONNECTION
2” (5.08 cm)
VENT
CONNECTION
INSTALL PROVIDED
2” DIAMETER
RUBBER SLEEVE
O
F
F
ON
