30
If the total external static pressure exceeds the maximum
listed on the furnace rating plate, check for closed dampers,
registers, undersized and/or oversized poorly laid out duct
work.
The temperature rise of the furnace must be within the tem
-
perature rise range listed on the furnace rating plate.
Checking Static Pressure
Figure 41
E
DGES
OF
SHEET
METAL
HOLES
MAY
BE
SHARP
. U
SE
GLOVES
AS
A
PRECAUTION
WHEN
REMOVING
SHEET
METAL
FROM
RETURN
AIR
OPENINGS
.
WARNING
Bottom Return Air Opening
[Upflow Models]
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:
Airflow area will be reduced by approximately 18% if
duct flanges are not unfolded. This could cause performance
issues and noise issues.
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.
When the furnace is installed without a cooling coil, it is rec
-
ommended 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.
CUT FOUR CORNERS
AFTER REMOVING SHEET
METAL
CUT USING TIN SNIPS
PRESS OUT BY HAND
SCRIBE LINES OUTLINING
DUCT FLANGES
Duct Flange Cut Outs
Figure 42
Filters - Read This Section Before Installing
The Return Air Duct work
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 dim
-
ples. Cut out the opening on these lines.
NOTE:
An undersized
opening will cause reduced airflow.
Refer to the following table to determine filter area require
-
ments.
Upflow Models
Minimum Recommended Filter Size
*M9C960303AN
1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*M9C960403AN
1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*M9C960603AN
1 - 16 X 25 Side or 14 X 24 Bottom Return
*M9C960603BN
1 - 16 X 25 Side or Bottom Return
*M9C960803BN
1 - 16 X 25 Side or Bottom Return
*M9C960804CN
1 - 16 X 25 Side or Bottom Return
*M9C961004CN
2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
*M9C961005CN
2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
*M9C961205DN
2 - 16 X 25 Side or 1 - 24 X 24 Bottom Return
Downflow Models
*C9C960403BN
2 - 10 X 20 or 1 - 14 X 25 Top Return
*C9C960603BN
2 - 10 X 20 or 1 - 14 X 25 Top Return
*C9C960803BN
2 - 14 X 20 or 1 - 16 X 25 Top Return
*C9C961005CN
2 - 14 X 20 or 1 - 20 X 25 Top Return
¹ = Use 2 - 16 X 25 filters and two side returns or 20 X 25 filter on bottom
return if furnace is connected to a cooling unit over 4 tons nominal capacity
Larger filters may be used, filters may also be centrally located
A combination of one side & bottom may be used instead of both sides
Change filters before occupants take ownership of a
new home!
Содержание C9C96 Series
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