Sequence Of Operation - Bard W3RV2-R Literature Assembly

SEQUENCE OF OPERATION

Modes of Operation
Cool Only Mode:
• Compressor will modulate from 100% down to 20%.
• Compressor will cycle off if thermostat/controller
set-point is reached.
Heat Only Mode:
• Electric heat Stage 1 operates at 1
point.
• Electric heat Stage 2 (if equipped) operates on 2
stage (-2°F below heating set-point).
Auto Mode:
• Cooling or heating automatically selected based on
building temperature vs. thermostat/controller set-
points and operates as described above.
CCVC (Continuous Compressor Variable Capacity):
• Compressor will modulate from 100% down to 20%.
• Compressor will not cycle off if thermostat/controller
set-point is reached, and would stay running at the
20% minimum capacity.
• If space temperature drops -2°F below cooling
set-point electric heat Stage 1 will then cycle to
maintain that condition.
• If Stage 2 electric heat is installed, and if required,
will cycle at -4°F below cooling set-point to
maintain that condition.
• If CCVC is terminated the controller will revert to
Cool or Auto operation.
• CCVC would be an Operating Mode for all
applications where continuous run of the
compressor is a requirement.
Testing and Troubleshooting Mode CCFC (Continuous
Compressor Fixed Capacity):
• This unit must be controlled with the digital
thermostat controller supplied with the unit. To test
or troubleshoot, change system mode to CCFC. This
will ensure unit runs continuously and in full capacity
mode. AHRI ratings are based on this mode of
operation.
CCFC (Continuous Compressor Fixed Capacity):
• The compressor is turned ON and locked ON as long
as the thermostat/controller is in Test Mode 2.
• When in CCFC the compressor does not modulate
but will be locked ON at 100% capacity.
• If space temperature drops -2°F below cooling
set-point electric heat Stage 1 will then cycle to
maintain that condition.
• If Stage 2 electric heat is installed, and if required,
will cycle at -4°F below cooling set-point to
maintain that condition.
• If CCFC is terminated the controller will revert to
Cool or Auto operation.
-stage heating set-
st
nd
Indoor Blower Operation
The indoor blower speed will modulate with the
compressor operation from 50% to 100% of operation.
Once compressor operation is at 50 or below, percent
airflow will be at 50% and no further reduction of
airflow will occur. Modulation is accomplished by
modulating a 0-10 volt signal from OUT 7 to the indoor
blower motor.
An additional option to maintain airflow at 100% is
also available. This selection is done at the thermostat/
controller under Fan Modes. Default is No for "Always
100%"setting. Change to Yes to disable indoor blower
modulation as described above.
Outdoor Fan Motor Operation
The outdoor fan motor speed is varied in response to
outdoor air temperature and pressure. The fan motor
will cycle on and off with the compressor when not
in a CCVC or CCFC mode. At all times above 122°F
OAT, the outdoor fan, OUT 9, will be energized at high
speed. From 122°F to 55°F the outdoor fan, OUT
9, will be set at normal outdoor airflow. Below 55°F
the outdoor fan will modulate to maintain a 300 psi
head pressure. This will act as a low ambient fan
cycling control. The output may go to zero output to
maintain the 300 PSI. The outdoor ECM motor will be
programmed with a minimum RPM allowed to protect
the bearing system. Any signal that is less than the
percent torque required to maintain the minimum RPM
will cause the motor to shut off. Once head pressure
rises the motor will restart.
These functions are regulated by the digital thermostat/
controller with input from the pressure transducer and
output signal to the Fan Motor.
Capacity Modulation and High Head Pressure Control
The pressure transducer monitors the high side
pressure providing input to the digital thermostat/
controller. It is powered using a 5VDC power supply
with a digital relay signaling the compressor unloader
solenoid as required. When the ECU head pressure
exceeds 615 PSI based on outdoor and indoor ambient
conditions the compressor will automatically start to
reduce capacity to stay online keeping the pressure at
or below 575 PSI. The thermostat/controller display
alternates between OD temperature and discharge
pressure. When compressor capacity is being reduced
due to high pressure conditions it will also indicate
"High Head Pressure Control" mode on the display. A
separate 650 PSI high pressure cutout switch is also
employed as additional safety device. See Compressor
Control Module on following page for more details.
Manual 2100-615A
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