28
Table 13 — Blower Performance Data
WSHP OPEN CONTROLS — The ECM fan is controlled by
an interface board that converts the fan speed outputs from the
WSHP Open control board to the signal used by the ECM mo-
tor (see Fig 35). The indicator LEDs allow the service techni-
cian to view the airflow mode that the WSHP Open control is
commanding. The table below indicates the illuminated LEDs
for each fan mode.
NOTE: Power must be off to the unit for at least three seconds
before the ECM will recognize a speed change. The motor will
recognize a change in the CFM Adjust setting (SW7 and SW8)
while the unit is powered.
The WSHP Open controller provides four different airflow
settings which can be set between the lowest airflow (tap 1) to
the highest airflow (tap 4). The lowest three airflow settings
(Fan Only, Low, and Medium) are set using SW3 and SW 4
while the highest airflow (High) is set independently using
SW5 and SW6. This provides the ability to better adjust the fan
performance of the unit to meet the required load conditions.
Cooling and Heating — The SW3 and SW4 DIP switch set-
tings determine the fan airflow (cfm) to be used during normal
Fan Only, Cooling, Heating, and Dehumidification modes (see
Table 14A). The fan speed and airflow is independent from the
compressor capacity control. During Fan Only operation, the
fan will operate at the Fan Only airflow value specified in the
table for the appropriate tap setting. Once either cooling or
heating is required and the compressor is energized, the fan
will increase the minimum airflow across the coil to the value
defined by the low fan selection. Coil freeze protection and ex-
cessive discharge air temperature protection are integral parts
of the WSHP Open controller function so the fan airflow can
increase to medium or high airflow as required and indepen-
dent of compressor capacity to prevent excessively hot or cold
supply air temperature and coil freeze-up. The selection of the
high fan airflow setting is independent of the other fan airflow
settings and is defined in Table 14B. The high airflow must be
chosen so that it is equal to or greater than the medium fan air-
flow. Therefore the tap setting for high fan (SW5 and SW6)
MUST equal or exceed the tap chosen for the SW3 and SW4.
Dehumidification — When Dehumidification is used, the fan
operates at the airflow setting defined by the Medium Fan air-
flow setting and the tap position of SW3 and SW4.
CFM Adjust — The CFM Adjust setting allows the balancer
to fine tune the actual airflow. SW7 and SW8 are used to set
the CFM Adjustment if necessary. The NORM setting is the
factory default. The (+) or (-) settings provide the ability to ad-
just the airflow by 15% or -15% as needed. A test posi-
tion is also provided but should not be used (see Table 11).
50PT
UNIT SIZE
MAX ESP
(in. wg)
FAN
MOTOR
(hp)
TAP
SETTING
COOLING MODE (cfm)
DEHUMIDIFICATION MODE (cfm)
HEATING MODE (cfm)
Stage 1
Stage 2
Fan
Stage 1
Stage 2
Fan
Stage 1
Stage 2
Fan
026
0.50
1
/
2
4
810
950
475
630
740
475
920
1060
475
3
725
850
425
560
660
425
825
950
425
2
620
730
370
490
570
370
710
820
370
1
520
610
300
—
—
—
600
690
300
038
0.50
1
/
2
4
1120
1400
700
870
1090
700
1120
1400
700
3
1000
1250
630
780
980
630
1000
1250
630
2
860
1080
540
670
840
540
860
1080
540
1
730
900
450
—
—
—
730
900
450
049
0.75
1
4
1460
1730
870
1140
1350
870
1560
1850
870
3
1300
1550
780
1020
1210
780
1400
1650
780
2
1120
1330
670
870
1040
670
1200
1430
670
1
940
1120
560
—
—
—
1010
1200
560
064
0.75
1
4
1670
2050
1020
1300
1600
1020
1860
2280
1020
3
1500
1825
920
1160
1430
920
1650
2050
920
2
1280
1580
790
1000
1230
790
1430
1750
790
1
1080
1320
660
—
—
—
1200
1470
660
072
0.75
1
4
1620
2190
1050
1270
1650
1050
1690
2230
1050
3
1500
1950
980
1170
1520
980
1600
2100
980
2
1400
1830
910
1100
1420
910
1400
1850
910
1
1320
1700
850
—
—
—
1240
1620
850
ECM INDICATORS LEDs
SPEED
G
Fan Only
G + Y1
Low Fan
G + Y1 + Y2
Med Fan
G + Y1 +W
High Fan