Freezestat Operation
IMPORTANT
Use of the freezestat feature is required in all instal- lations using CBWMV units.
The CBWMV unit is equipped with a
The
Freezestat Field Wiring |
Figure 13
BDC3 Variable Blower Control Board
CBWMV units are equipped with a variable speed motor that is capable of maintaining a specified CFM throughout the external static range. A particular CFM can be obtained by positioning jumpers (COOL, HEAT, and ADJUST) on the BDC3 control board. The COOL and HEAT jumpers are labeled 1, 2, 3, and 4. Each of the numbers corre- sponds with an air volume (CFM) setting. The ADJUST jumper is labeled TEST, −, +, and NORM. The + and − pin settings are used to add or subtract a percentage of the CFM selected. The TEST jumper is used to operate the motor in the test mode. The DELAY jumper controls ramp- ing profiles.
Figure 14 shows the BDC3 control board. Use tables 5 through 9 to determine the correct air volume for heat and cool speed taps.
Diagnostic LEDs located on the BDC3 control board are provided to aid in identifying the unit’s mode of operation. Certain scenarios will arise depending on the jumper posi- tions. Read through the jumper settings sections before adjusting blower speed. Refer to figure 14 for identification.
Continuous Low Blower Option
Refer to the blower speed chart located on the CBWMV unit wiring diagram for factory set cooling, heating and low (continuous) blower speeds. Systems using a cooling ther- mostat subbase may operate continuous blower (factory- set to operate at 38% of
Heating or cooling demand will cause blower to go to heat or cool speed.
Blower Speed Adjustments
Diagnostic LEDs
RUN LED Indicates a demand for blower operation in either the heating mode or continuous fan−only mode. RUN LED will not illuminate during a cooling demand.
CFM LED Indicates the CFM at which the unit is operat- ing. The light flashes once for approximately every 100 CFM. For example, if the unit is operating at 1000 CFM, CFM LED will flash 10 times. If the CFM is 1150, CFM LED will flash 11 full times plus one fast or half flash.
At times the light may appear to flicker or glow. This takes place when the control is communicating with the motor between cycles. This is normal operation.
The appropriate speed according to application and CFM need is selected by moving jumper pins.
BDC3 Variable Speed Control Board
JP1 15 PIN PLUG (BOARD TO MOTOR)
ACCESSORY RELAY CON- TACTS (DRIVES OP-
TIONAL ACCESSORY RELAY)
OPERATIONAL SELECTOR PINS (AFFECTS BOTH HEATING AND COOLING MODES)
HEATING SPEED | COOLING SPEED | FAN DELAY | DIAGNOSTIC |
SELECTOR PINS | SELECTOR PINS | SELECTOR PINS | LEDS |
Figure 14
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