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5715184-BIM-A-0519
DOWNWARD VENTING
In some applications, it may be necessary to run the vent pipe and air
intake downwards. If this is to be done, the following rules must be fol-
lowed.
• A condensate trap hose must be connected to both the air intake
pipe and the vent pipe at the lowest part of the horizontal run.
• The condensate drain trap must have a trap of a minimum of 6 in.
• The total vertical downward distance must not exceed 16 ft.
• The condensate drain hose must be connected to a condensate
drain pump, a open or vented drain or into the condensate drain
line from the furnace.
• The condensate drain lines must not pass through unconditioned
spaces where the temperature may fall below freezing.
• The condensate drain line must be primed at the initial start-up
prior to the start of heating season.
FIGURE 27: Downward Venting
COMBUSTION AIR SUPPLY
NOTICE
When installed in a Manufactured (Mobile) Home, combustion air
shall not be supplied from occupied spaces.
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 only possible combus-
tion air intake configurations.
• OUTDOOR COMBUSTION AIR: This is a direct vent configura-
tion where the combustion air is supplied through a PVC or ABS
pipe that is connected to the PVC coupling attached to the fur-
nace and is terminated in the same atmospheric zone as the
vent. This type of installation is approved on all models. Refer to
Figure 28.
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 28) that brings air
in from the outdoors to the furnace combustion air intake collar on the
burner box. The second pipe (shown in Figure 28) is the furnace vent
pipe.
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.
22
FIGURE 28: Direct Vent Air Intake Connection and Vent Connection
The combustion air intake pipe must be located either through the wall
(horizontal or side vent) or through the roof (vertical vent). Care must be
taken to locate side vented systems where trees or shrubs do not block
or restrict supply air from entering the terminal.
Also, the terminal assembly must 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.
WARNING
!
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.
An unconfined space is not less than 50 cu.ft (1.42 m
hr (0.2928 kW) input rating for all of the appliances installed in that
area.
Rooms communicating directly with the space containing the appli-
ances are considered part of the unconfined space, if openings are fur-
nished with doors.
A confined space is an area with less than 50 cu.ft (1.42 m
Btu/hr (0.2928 kW) input rating for all of the appliances installed in that
area. The following must be considered to obtain proper air for combus-
tion and ventilation in confined spaces.
Combustion Air Source From Outdoors
The blocking effects of louvers, grilles and screens must be given con-
sideration in calculating free area. If the free area of a specific louver or
grille is not known, refer to Table 11 to estimate free area.
Table 11: Estimated Free Area
Wood or Metal
Louvers or Grilles
Screens+
* Do not use less than 1/4 in. (0.635 cm) mesh
+ Free area of louvers and grille varies widely. The installer must follow the
louver or grille manufacturer's instructions.
3
) per 1,000 Btu/
3
) per 1,000
Wood 20-25%*
Metal 60-70% *
1/4 in. (0.635 cm)
mesh or larger 100%
Johnson Controls Ducted Systems
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