Safety Devices & The Upm Controller - Bosch CE SPLIT series Installation And Maintenance Manual

10
CE Split Series
thermostat inputs on to the rest of the control
circuit. Remember to always turn off unit power at
the circuit breaker before attaching or disconnecting
any wiring from these connections to avoid
accidental short circuits that can damage unit
control components.
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.
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".
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.
• 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
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Safety devices and the uPM Controller
enter a soft lockout. The compressor will not be
energized until the low pressure switch closes and the
anti-short cycle time delay expires. If the low pressure
switch opens 2–4 times in 1 hour, the unit will enter a
hard lock out and need to be reset.
• brownouT/SurGE/PowEr InTErruPTIon
ProTECTIon—The brownout protection in the UPM
board will shut down the compressor if the
incoming power falls below 18 VAC. The compressor
will remain off till the voltage goes above 18 VAC and
the anti short cycle timer (300 seconds) times out.
The unit will not go into a hard lockout.
• MalfunCTIon ouTPuT—The controller has a set of
wet contacts for remote fault indication or dry contacts
for communication with a DDC controller or BMS. The
fault output will depend on the dip switch setting for
"ALARM". If it set to "CONST', a constant signal will be
produced to indicate a fault has occurred and the unit
requires inspection to determine the type of fault. If it is
set to "PULSE", a pulse signal is produced and a fault
code is detected by a remote device indicating the fault.
See L.E.D. Fault Indication below for blink code
explanations. The remote device must have a malfunction
detection capability when the UPM board is set to "PULSE" .
• TEST dIP SwITCH—A test dip switch is provided to
reduce all time delay settings to 5 seconds during
troubleshooting or verification of unit operation.
Note that operation of the unit while in test mode
can lead to accelerated wear and premature failure
of the unit. The "TEST" switch must be set back to
"NO" for normal operation.
• frEEZE SEnSor—This is optional and can be set
to ignore or monitor a freeze sensor. There are 2
configurable freeze points, 35°F & 15°F. The unit
will enter a soft lock out until the temperature
climbs above the set point and the anti-short cycle
time delay has expired. The freeze sensor may not
provide protection in the case of loss of flow in the
heating mode. A flow switch or pressure
differential switch is recommended to prevent unit
operation in case of loss of flow.
Caution
Subject to change without prior notice
If unit is employing a fresh water system (no
anti-freeze protection), it is extremely important to
have the "Freeze" switch set to 35°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.
Revised 03-11