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Return Air Connections
FIRE HAZARD
A failure to follow
this warning
could cause personal
injury,
death and/or property
damage.
Never
connect
return-air
ducts
to the back of the furnace.
Follow
instructions
below.
The return-air
duct must be connected
to return-air
opening
(bottom inlet). DO NOT cut into casing sides (left or right).
Bypass humidifier connections should be made at ductwork or coil
casing sides exterior to furnace. See Fig. 26.
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel, perform
the following:
1. Tilt or raise furnace and remove 4 screws holding bottom
plate. See Fig. 23.
2. Remove bottom plate.
3. Remove bottom closure panel.
4. Reinstall bottom plate and screws.
Horizontal
Installation
NOTE:
The furnace
must be pitched
forward
as shown
in Fig. 24
for proper
condensate
drainage.
FIRE,
EXPLOSION,
AND
CARBON
MONOXIDE
POISONING
HAZARD
Failure to follow this warning
could result in personal
injury, death, or property damage.
Do not install the furnace on its back or hang furnace with
control
compartment
facing
downward.
Safety control
operation
will
be
adversely
affected.
Never
connect
return-air ducts to the back of the furnace.
MINOR
PROPERTY
HAZARD
Failure to follow this caution may result in minor property
damage.
Local codes may require a drain pan under entire furnace and
condensate trap when a condensing furnace is used in an attic
application or over a finished ceiling.
The furnace can be installed horizontally in an attic or crawlspace
on either the left-hand (LH) or right-hand
(RH) side. The furnace
can be hung from floor joists, rafters or trusses or installed on a
non-combustible
platform, blocks, bricks or pad.
Platform
Furnace
Support
Construct working platform at location where all required furnace
clearances are met.
See Table 2 and Fig. 28. For furnaces with
1-in. (25 mm) clearance requirement
on side, set furnace on
non-combustible
blocks, bricks or angle iron. For crawlspace
installations, if the furnace is not suspended from the floor joists,
the ground underneath furnace must be level and the furnace set on
blocks or bricks.
Suspended
Furnace
Support
The furnace must be supported
under the entire length of the
furnace with threaded rod and angle iron.
See Fig. 29.
Secure
angle iron to bottom of furnace as shown.
Roll-Out
Protection
Provide a minimum 12-in. x 22-in. (305 x 559 mm) piece of sheet
metal for flame roll-out
protection in front of burner area for
furnaces closer than 12-in. (305 mm) above the combustible deck
or suspended furnaces closer than 12-in. (305 mm) to joists, The
sheet metal MUST extend underneath the furnace casing by 1-in.
(25 mm) with the door removed.
The bottom closure panel on furnaces of widths 17-1/2-in.
(445
mm) and larger may be used for flame roll-out protection when
bottom of furnace is used for return air connection, See Fig. 28 for
proper orientation of roll-out shield.
Supply
Air Connections
For a furnace not equipped with a cooling coil, the outlet duct shall
be provided with a removable access panel. This opening shall be
accessible when the furnace is installed and shall be of such a size
that the heat exchanger can be viewed for possible openings using
light assistance or a probe can be inserted for sampling the air
stream. The cover attachment shall prevent leaks.
Connect supply-air
duct to flanges on furnace supply-air
outlet.
Bend flange upward to 90 ° with wide duct pliers.
See Fig. 21.
The supply-air
duct must be connected
to ONLY the furnace
supply-outlet-air
duct flanges or air conditioning
coil casing
(when used). DO NOT cut main furnace casing side to attach
supply air duct, humidifier, or other accessories. All supply-side
accessories MUST be connected to duct external to furnace main
casing.
Return
Air Connections
The return-air duct may be connected to bottom of the furnace.
The side of casing that faces downward may also be used for return
air connection.
A combination
of the bottom and downward
facing side may also be used. The upward facing side of the casing
cannot be used as a return air connection.
See Fig. 27.
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel, perform
the following:
1. Tilt or raise furnace and remove 4 screws holding bottom
plate. See Fig. 23.
2. Remove bottom plate.
3. Remove bottom closure panel.
4. Reinstall bottom plate and screws.
Side Return Air Inlet
These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. This panel MUST be in place when
side return air inlet(s) are used without a bottom return air inlet.
Not all horizontal
furnaces
are approved for side return air
connections
See Fig. 27.
2O
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