Thermostat Connections; Safety Devices And The Upm Controller - Bosch BP070 Installation And Maintenance Manual

8 CP/BP Series

THerMoSTaT ConneCTIonS

Thermostat wiring is connected to a 7 position low
voltage terminal block in the electrical box. The
thermostat connections and their functions are as
follows:
y Compressor Operation
G Fan
o Reversing Valve (energized in cooling)
C Transformer 24 VAC Common – 3 Connections
r Transformer 24 VAC Hot
If the unit is being connected to a thermostat with a
malfunction light, this connection is made at the
unit alarm output.
If the thermostat is provided with a malfunction
light powered off of the common (C) side of the
transformer, the UPM board "ALR" jumper setting
must be set to "HOT".
If the thermostat is provided with a malfunction
light powered off of the common (C) side of the
transformer, the unit must be provided with a
malfunction relay (Bosch option # 660-006) to
properly energize the light. The relay coil will be
wired across the (ALR) and (C) contacts on the
unit's UPM board and the relay's normally open
contacts across (ALR) and the malfunction light
connection on the thermostat. 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.
Always disconnect power before changing jumper
positions on the interface board and reset the unit
afterward.
SafeTy deVICeS and THe
uPM ConTroller
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.
6 720 220 045
C–GND
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.
• Optional freeze protection sensor located on the
leaving side of the water coil prevents unit
operation below 35°F or 15°F (depending on dip
switch setting). The freeze dip switch must be set
to "ON".
Caution
• Condensate overflow protection sensor located in
the drain pan of the unit and connected to the
'COND' terminal on the UPM board.
The UPM includes the following features:
• anTI-SHorT CyCle TIMe—5 minute delay on
break timer to prevent compressor short cycling.
• randoM STarT—Each controller has a unique
random start delay ranging from 270 to 300 seconds to
reduce the chances of multiple units simultaneously
starting after initial power up or after a power
interruption, creating a large electrical spike.
• loW PreSSure ByPaSS TIMer—If the compressor is
running and the low pressure switch opens, then the
control will keep the compressor on for 120 seconds.
After 2 minutes if the low pressure switch remains
open, the control will shut down the compressor and
enter a soft lockout. The compressor will not be
Subject to change without prior notice
Thermostat Connections
POWER
G
LPC2 LPC1 Y
STATUS
R
UNIT PROTECTION MODULE
FREEZE ON OFF
TEMP 35°F 15°F
LOCKOUT 4 2
RESET R Y
ALARM CONT PULSE
TEST YES NO
C C
The factory default for the Freeze setting is in
"ON" position. If the freeze stat option is not
ordered, the switch must be repositioned to the
"OFF" position.
Y HPC HPC
FHP P\N 641–244
DRY HOT
ALR
DRY HOT R R CC
Revised 01-11