10
Safety Devices and UPM Controller
1
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9
10
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17
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8
A14120
(1) Board Power Indicator
(10) Compressor Contact Output
(2) UPM Status LED Indicator
(11) High Pressure Switch Connection
(3) Water Coil Freeze Protection
Temperature Selection [R30]
(12) Call for Compressor Y1
(4) Air Coil Freeze Protection
Temperature Selection
(13) Low Pressure Switch Connection
(5) UPM Board Settings
(14) 24VAC Power Common
(6) Water Coil Freeze Connection
(15) Condensate Overflow Sensor
(7) Air Coil Freeze Connection
(16) Dry Contact
(8) LCD Unit Display Connection
(17) UPM Ground Standoff
(9) 24VAC Power Input
Fig. 8 -- Safety Device and UPM Controller
NOTES
:
1. If the unit is being connected to a thermostat with a mal-
function light, this connection is made at the unit malfunc-
tion output or relay. Refer to Fig. 8.
2. If the thermostat is provided with a malfunction light pow-
ered off of the common (C) side of the transformer, a
jumper between “R” and “COM” terminal of “ALR” con-
tacts must be made.
3. If the thermostat is provided with a malfunction light pow-
ered off of the hot (R) side of the transformer, then the ther-
mostat 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:
S
High pressure switch located in the refrigerant discharge line and
wired across the HPC terminals on the UPM.
S
Low pressure switch located in the unit refrigerant suction line
and wired across terminals LPC1 and LPC2 on the UPM.
NOTE
: UPM Board Dry Contacts are normally open (NO)
S
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 26
_
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 Fig. 8, item (3) for resistor location),
Refer to Fig. 9 for sensor location.
A14121
Fig. 9 -- Freeze Protection Sensor Location
CAUTION
!
UNIT DAMAGE AND/OR OPERATION HAZARD
Failure to follow this caution may result in unit damage
and/or improper equipment operation.
If unit is employing a fresh water system (no anti--freeze
protection), it is extremely important to have the Freeze1
R30 resistor set to 26
_
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.
S
Evaporator freeze protection sensor, mounted after the thermal
expansion device and the evaporator, monitors refrigerant
temperature between the evaporator 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
26
_
F. See Fig. 10.
A14122
Fig. 10 -- Evaporator Freeze Protection Sensor Location
