1083293-UIM-D-1116
30
Johnson Controls Unitary Products
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 B149.2 Installation Code - latest
editions.
This furnace is certified to be installed with one of three possible com-
bustion air intake configurations.
1.
OUTDOOR COMBUSTION AIR:
This is a direct vent configuration
where the combustion air is supplied through a PVC or ABS pipe
that is connected to the PVC coupling attached to the furnace and
is terminated in the same atmospheric zone as the vent. This type
of installation is approved on all models. Refer to Figure 36.
2.
AMBIENT COMBUSTION AIR:
Combustion air is supplied from
the area surrounding the furnace through openings in the furnace
casing. The combustion air and the vent pipes are not terminated
in the same atmospheric zone. Refer to Figure 31 for vent termina-
tions. Refer to "Ambient Combustion Air Supply" for proper instal-
lation. Refer to Figures 37 and 38.
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 39 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 36) 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 36) 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.”
Ambient Combustion Air Supply
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 furnace. A single, properly sized pipe from the
furnace vent connector to the outdoors must be provided. It is recom-
mended that the supplied intake coupling & 18” of pipe be attached to
the furnace to prevent accidental blockage or combustion air intake.
An
unconfined space
is not less than 50 ft
3
(1.42 m
3
) per 1,000 BTU/
hr (0.2928 kW) input rating for all of the appliances installed in that
area.
FIGURE 34:
Double Horizontal Combustion Air Intake and Vent
Termination
FIGURE 35:
Double Vertical Combustion Air Intake and Vent
Termination
NOTICE
An optional plastic birdscreen is shipped in the loose parts bag with
every furnace. This may be installed in the intake collar to prevent
any small objects from entering the furnace.
VENT
2”
MIN.
COMBUSTION AIR
MIN.
6”
FIGURE 36:
Direct Vent Air Intake Connection and Vent Connection
FIGURE 37:
Combustion Airflow Path Through The Furnace Casing
WARNING
This type of installation requires that the supply air to the appliance(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 create 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 appliance to soot and gen-
erate dangerous levels of CARBON MONOXIDE, which can lead to
serious injury, property damage and / or death.
Connects to
collar on top
of burner box
Vent pipe clamps
into outlet of
drain coupling
COMBUSTION AIR
Vent pipe clamps
into outlet of
drain coupling
!
