PRODUCT DESIGN
44
Rev. 0
To ensure proper unit performance follow the filter sizes
given in the following filter sizing charts.
Nom.
Area
Nom.
Area
Size
(in²)
Size
(in²)
045_30
1200
1
24x24x1
576
1
16x25x1 400
070_30
1400
1
25x30x1
750
1
16x25x1 400
070_40
1600
1
25x30x1
800
1
16x25x1 400
090_40
1600
1
25x30x1
800
1
16x25x1 400
090_50
2000
2
20x25x1 1000
2
16x25x1 800
115_50
2000
2
20x25x1 1000
2
16x25x1 800
Max CFM
Model
Input___Air Flow
Qty
Qty
Side Return Filters
Minimum Recommended Size For Maximum CFM
Disposable*
Permanent*
Nominal
Area
Size
(in²)
045_30
1200
1
14x25x1
350
070_30
1400
1
14x25x1
350
070_40
1600
1
16x25x1
400
090_40
1600
1
16x25x1
400
090_50
2000
1
20x25x1
500
115_50
2000
1
20x25x1
500
Model
Input___Air Flow
Qty
Bottom Return Filter
Minimum Recommended Size For Maximum CFM
Permanent
Max CFM
Nom.
Area
Size
(in²)
045_30
1200
2
15X20X1
576
070_30
1400
2
15X20X1
750
070_40
1600
2
15X20X1
800
090_40
1600
2
15X20X1
800
090_50
2000
2
15X20X1
1000
115_50
2000
2
15X20X1
1000
Counterflow Filters
Minimum Recommended Size For Maximum CFM
Model
Input___Air Flow
Max CFM
Qty
Filter
Type*
Dimension
"A"
Permanent
11 1/4
Disposable
14 1/4
Permanent
13
Nominal
Area Nominal
Area
Size
(in²)
Size
(in²)
045_30 1200
1
15x20x1
600
1
15x25x1
300
070_30 1400
1
16x20x1
800
1
16x25x1
4000
070_40
1600
1
16x25x1
800
1
16x25x1
400
090_40
1600
1
16x25x1
800
1
16x25x1
400
090_50
2000
1
20x25x1
1000
1
20x25x1
500
115_50
2000
1
20x25x1
1000
1
20x25x1
500
Model Input___Air
Flow
Max CFM
Horizontal Installations
Minimum Recommended Size For Maximum CFM
Qty
Qty
Disposable*
Permanent*
Upright Installations
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register, the bottom of the
blower compartment (upflows), a side panel external filter
rack kit (upflows), or the ductwork above a counterflow fur-
nace. As an alternative a media air filter or electronic air
cleaner can be used as the requested filter. Review and
follow the filter sizes given in the previous filter sizing charts
to ensure proper unit performance. The following figures
show possible filter locations.
Note: A ductwork access door must be used in counter-
flow applications to allow filter removal.
FI
LT
ER
FILTER
FI
LT
ER
SUPPLY
AIRFLOW
EXTERNAL
FILTER
RACK KIT
CENTRAL
RETURN
GRILLE
BOTTOM
RETURN
RE
T
URN
AIR
F
L
O
W
RE
T
URN
AIR
F
L
O
W
RETURN
AIRFLOW
Possible Upright Upflow
Filter Locations
FI
LTE
R
FI
LTE
R
FI
L
T
ER
SUPPLY
AIRFLOW
OPTIONAL
FILTER
ACCESS
DOOR
CENTRAL
RETURN
GRILLE
RETURN
DUCT
JUNCTION
BOX
RET
U
RN
A
IR
F
LOW
Possible Upright Counterflow
Filter Locations
Horizontal Installations
Filters must be installed in the central return register. Refer
to the previous filter charts for recommended minimum fil-
ter sizes.
Startup Procedure and Adjustment
Furnace must have a 115 VAC power supply properly con-
nected and grounded. Proper polarity must be maintained
for correct operation. Refer to POLARIZATION AND PHAS-
ING section on page 52 of this service manual for the cor-
rect procedures on checking for proper polarization of the
incoming power supply.
