Table of Contents
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1
2
3
4
5
17
15
7
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 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
Fig. 43 — Unit Protection Module (UPM)
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 board.
•
UPM board dry contacts are normally open (NO).
•
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 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. 43, Item 3 for resistor
location. If unit is employing a fresh water system (no
antifreeze 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 pro-
tect heat pump from freezing if a freeze sensor is included.
•
Evaporator freeze protection sensor, mounted between the
thermal expansion device and the evaporator, monitors re-
frigerant temperature between the evaporator coil and
11
13
12
9
10
58
thermal expansion valve. If temperature drops below or re-
mains 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. 44
and 45.
•
The condensate overflow protection sensor is located in
the drain pan of the unit and connected to the 'COND' ter-
minal on the UPM board.
Fig. 44 — Water-Side Freeze Protection Sensor
Fig. 45 — Air Coil Freeze Protection Sensor
The UPM board includes the following features:
Anti-short Cycle Timer
A 5-minute delay on break timer prevents compressor short
cycling.
Random Start
Each controller has an unique random start delay ranging from
270 to 300 seconds on initial power up to reduce the chance of
multiple units simultaneously starting at the same time after power
up or after a power interruption, thus avoiding creating large in-
rush current.
Low Pressure Bypass Timer
If the compressor is running and the low-pressure switch opens,
the controller will keep the compressor ON for 120 seconds. After
2 minutes if the low-pressure switch remains open, the controllers
will shut down the compressor and enter a soft lockout. The com-
pressor 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 to 4 times in 1 hour, the unit will enter a hard lock-
out. In order to exit hard lockout power to the unit would need to
be reset.
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