Bosch LM024 Operating Instructions Manual page 8

8 | Electrical
If the unit is being connected to a thermostat
with a malfunction light, this connection is made
at the unit malfunction output or relay. Refer to
Figure #6.
If the thermostat is provided with a malfunction
light powered off of the common (C) side of the
transformer, a jumper between "R" and "COM"
terminal of "ALR" contacts must be made.
If the thermostat is provided with a malfunction
light powered off of the hot (R) side of the
transformer, then the thermostat malfunction
light connection should be connected directly to
the (ALR) contact on the unit's UPM board.
Each unit is factory provided with a Unit Protection
Module (UPM) that controls the compressor
operation and monitors the safety controls that
protect the unit.
Safety controls include the following:
• High pressure switch located in the refrigerant
discharge line and wired across the HPC
terminals on the UPM
• Low pressure switch located in the unit
refrigerant suction line and wired across
terminals LPC1 and LPC2 on the UPM.
UPM Board Dry Contacts are Normally Open
(NO)
8 733 920 847 (2014/01)
• Water side freeze protection sensor, mounted
close to condensing water coil, monitors
refrigerant temperature between condensing
water coil and thermal expansion valve. If
temperature drops below or remains at freeze
limit trip for 30 seconds, the controller will
shut down the compressor and enter into a
soft lockout condition. The default freeze limit
trip is 30°F, however this can be changed to
15°F by cutting the R30 or Freeze1 resistor
located on top of DIP switch SW1. Refer to
Figure #6, item [3] for resistor location. (Refer
to Figure #7 for sensor location)
If unit is employing a fresh water system (no
anti-freeze protection), it is extremely
important to have the Freeze1 R30 resistor
set to 30°F in order to shut down the unit at
the appropriate leaving water temperature
and protect your heat pump from freezing if
a freeze sensor is included.
• The condensate overflow protection sensor is
located in the drain pan of the unit and
connected to the 'COND' terminal on the UPM
board. (Figure #8)
Subject to change without prior notice
LM CS Series Heat Pump
Figure # 7
Figure # 8
LM CS Series Heat Pump