31
When the furnace is installed without a cooling coil, it is
recommended that a removable access panel be provided
in the outlet air duct. 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 visual light
inspection or such that a sampling probe can be inserted
into the airstream. The access panel must be made to
prevent air leaks when the furnace is in operation.
When the furnace is heating, the temperature of the return
air entering the furnace must be between 55°F and 100°F.
f
Ilters
- r
eaD
t
HIs
s
ectIon
B
efore
I
nstallIng
t
He
r
eturn
a
Ir
D
uct
CUT USING TIN SNIPS
SCRIBE LINES OUTLINING
DUCT FLANGES
D
ual
f
lange
c
ut
o
uts
f
Igure
38
Filters must be used with this furnace. Discuss filter
maintenance with the building owner. Filters do not ship
with this furnace, but must be provided, sized and installed
externally by the installer. Filters must comply with UL900
or CAN/ULCS111 standards. Damage or repairs due to
the installation of the furnace without filters is not covered
under the warranty.
On upflow units, guide dimples locate the side return cutout
locations. Use a straight edge to scribe lines connecting
the dimples. Cut out the opening on these lines.
note: a
n
unDersIZeD
oPenIng
wIll
cause
reDuceD
aIrflow
.
H
orIZontal
I
nstallatIons
Filters must be installed in either the central return register
or in the return air duct work.
B
ottoM
r
eturn
a
Ir
o
PenIng
[u
Pflow
M
oDels
]
The bottom return air opening on upflow models utilizes
a “lance and cut” method to remove sheet metal from the
duct opening in the base pan. To remove, simply press
out the lanced sections by hand to expose the metal strips
retaining the sheet metal over the duct opening. Using
tin snips, cut the metal strips and remove the sheet metal
covering the duct opening. In the corners of the opening,
cut the sheet metal along the scribe lines to free the duct
flanges. Using the scribe line along the duct flange as a
guide, unfold the duct flanges around the perimeter of the
opening using a pair of seamer pliers or seamer tongs.
note: a
Irflow
area
wIll
Be
reDuceD
BY
aPProxIMatelY
18%
If
Duct
flanges
are
left
In
factorY
PosItIon
. t
HIs
coulD
cause
PerforMance
Issues
anD
noIse
Issues
.
Digital
Manometer
f
Igure
37
When the furnace is used in connection with a cooling unit,
the furnace should be installed in parallel with or on the
upstream side of the cooling unit to avoid condensa tion
in the heating element. With a parallel flow arrange ment,
the dampers or other means used to control the flow of
air must be adequate to prevent chilled air from entering
the furnace and, if manually operated, must be equipped
with means to prevent operation of either unit unless the
damper is in the full heat or cool position.
WARNING
e
Dges
of
sHeet
Metal
Holes
MaY
Be
sHarP
. u
se
gloVes
as
a
PrecautIon
wHen
reMoVIng
sHeet
Metal
froM
return
aIr
oPenIngs
.
