Bosch EP015, Installation And Maintenance Manual

Page: 7 / 40

7
EP Series
8733922168 Revised 12-13 Subject to change without prior notice
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.
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.
Figure #5
[1] Board Power Indicator
[2] UPM Status LED Indicator
[3] Water Coil Freeze Protection Temperature
Selection [R30]
[4] Air Coil Freeze Protection Temperature
Selection
[5] UPM Board Settings
[6] Water Coil Freeze Connection
[7] Air Coil Freeze Connection
[8] LED Status-Diagnostic Connection
[9] 24VAC Power Input
[10] Compressor Contact Output
[11] High Pressure Switch Connection
[12] Call for Compressor Y1
[13] Low Pressure Switch Connection
[14] 24VAC Power Common
[15] Condensate Overflow Sensor
[16] Dry Contact
[17] UPM Ground Standoff
Caution
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.
Caution
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.
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 #5.
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)
Thermostat Connections