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12
AIR DELIVERY -- CFM (BOTTOM RETURN WITH FILTER)* CONTINUED
UNIT SIZE
OPERATING
MODE
CFM
AIRFLOW
SETTING
EXTERNAL
STATIC
PRESSURE
RANGE*
EXTERNAL STATIC PRESSURE (ESP)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
100---20#
Low Heat
1110†
0---1.0
1060
1075
1080
1095
1110
1110
1110
1110
1110
1110
High Heat
1525
0---1.0
1525
1525
1525
1525
1520
1515
1515
1515
1515
1515
††
2---Ton A/C
Cooling
700
0---0.50‡
700
700
700
690
685
††
2---1/2---Ton A/C
Cooling
875
0---0.50‡
865
875
870
870
875
3---Ton A/C
Cooling
1050
0---1.0‡
1035
1045
1050
1045
1050
1050
1050
1050
1050
1045
3---1/2---Ton A/C
Cooling
1225
0---1.0‡
1180
1195
1215
1225
1225
1225
1225
1225
1225
1225
4---Ton A/C
Cooling
1400
0---1.0‡
1400
1400
1400
1400
1400
1400
1400
1395
1375
1365
5---Ton A/C
Cooling
1750
0---1.0
1740
1745
1750
1750
1750
1750
1750
1750
1750
1740
Maximum
2000
0---1.0
2000
2000
2000
2000
2000
2000
1985
1965
1940
1910
120---20
Low Heat
1380†
0---1.0
1345
1365
1380
1380
1380
1380
1380
1375
1360
1355
High Heat
1885
0---1.0
1875
1880
1885
1885
1885
1885
1885
1885
1880
1870
††
2---Ton A/C
Cooling
700
0---0.50‡
700
700
700
700
695
††
2---1/2---Ton A/C
Cooling
875
0---0.50‡
875
875
875
870
870
3---Ton A/C
Cooling
1050
0---1.0‡
1035
1040
1050
1050
1050
1050
1050
1025
1005
1000
3---1/2---Ton A/C
Cooling
1225
0---1.0‡
1205
1210
1225
1225
1225
1225
1225
1225
1220
1215
4---Ton A/C
Cooling
1400
0---1.0‡
1390
1400
1400
1400
1400
1400
1395
1385
1370
1360
5---Ton A/C
Cooling
1750
0---1.0‡
1745
1740
1745
1745
1745
1745
1745
1740
1730
1715
6---Ton A/C
Cooling
2100
0---1.0
2100
2100
2100
2100
2100
2095
2075
2040
1975
1910
Maximum
2100
0---1.0
2100
2100
2100
2100
2100
2095
2075
2040
1975
1910
* Actual external static pressure (ESP) can be determined by using the fan laws (CFM
2
proportional to ESP); such as, a system with 1750 CFM at 0.5 ESP
would operate at high---heating airflow of 1500 CFM at 0.37 ESP and low---heating airflow of 705 CFM at 0.08 ESP.
{
Low heat CFM when low---heat rise adjustment switch (SW1---3) and comfort/efficiency adjustment switch (SW1---4) on control center are OFF.
}
Ductwork must be sized for high---heating CFM within the operational range of ESP.
{{
Operation within the blank areas of the chart is not recommended because high---heat operation will be above 1.0 ESP.
# All airflows for 21 in. casing size furnaces are 5% less on side return only installations.
58U
VB