Bosch TA Series User Manual

6 720 220 046
Revised 05-12
9
TA Series
SAFETY DEVICES AND THE
UPM CONTROLLER
Each unit is factory provided with a Unit Protection
Module (UPM) that controls the compressor opera-
tion 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, 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 R42 resistor located on top of DIP switch SW1.
• The optional condensate over ow protection
sensor (standard on horizontal units) is located in
the drain pan of the unit and connected to the
‘COND’ terminal on the UPM board.
Freeze
Protection
Sensor
Caution
If freeze protection sensor is not installed, a
jumper between freeze contacts must be installed
on the UPM board otherwise unit will not start.
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
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.
Safety Devices and the UPM Controller

Bosch TA Series Specifications

General

Brand	Bosch
Model	TA Series
Category	Heat Pump
Language	English