Bosch QV Series Installation, Operation And Maintenance Manual page 29

QV Series Heat Pumps
• FREEZE SENSOR: The default setting for the
freeze limit trip is 26°F (Sensor 1); however,
this can be changed to 15°F by cutting the R30
resistor located on top of the DIP switch SW1,
freeze limit trip should only be changed to 15°F
when a closed loop system with appropriate
antifreeze mixture is used. Since Freeze Sensor
2 is dedicated to monitor the load side coil it is
recommended to leave the factory default
setting on the board. The UPM controller will
constantly monitor the refrigerant temperature
with the sensor mounted close to the
condensing water coil between the thermal
expansion valve and water coil. If temperature
drops below or remains at the freeze-limit trip
for 30 seconds, the controller will shut the
compressor down and enter into a soft-lockout
condition. Both the status LED and the alarm
contact will be active. The status LED will be
active, blinking the fault code. The LED will
flash (3 times) the code associated with this
alarm condition. If this alarm occurs 2 times (or
4 if Dip switch is set to 4) within an hour the
UPM controller will enter into a hard-lockout
condition. It will constantly monitor the
refrigerant temperature with the sensor
mounted close to the evaporator between the
thermal expansion valve and evaporator coil as
shown in Fig. 17. If temperature drops below
or remains at the freeze limit trip for 30
seconds, the controller will shut the
compressor down and enter into a soft-lockout
condition. Both the status LED and the alarm
contact will be active. The status LED will be
active, blinking the fault code. The LED will
flash 3 times the code associated with this
alarm condition. If this alarm occurs 2 times (or
4 if Dip switch is set to 4) within an hour the
controller will enter into a hard-lockout
condition.
NOTICE: The freeze sensor will not guard
against the loss of water. A flow switch is
recommended to prevent the unit from
running if water flow is lost or reduced.
QV Series Heat Pumps
Safety Devices and the UPM Controller Overview | 29
• INTELLIGENT RESET: If a fault condition is
initiated, the five-minute delay on break time
period is initiated and the unit will restart after
these delays expire. During this period the
fault LED will indicate the cause of the fault. If
the fault condition still exists or occurs 2 or 4
times (depending on 2 or 4 setting for Lockout
dip switch) before 60 minutes, the unit will go
into a hard lockout and requires a manual
lockout reset.
• LOCKOUT RESET: A hard lockout can be reset
by turning the unit thermostat off and then
back on when the "RESET" dip switch is set to
"Y" or by shutting off unit power at the circuit
breaker when the "RESET" dip switch is set to
"R."
The blower motor will remain active during
a lockout condition.
Subject to change without prior notice
8733829041 (2021/07)