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SM Series Heat Pump
NOTICE: 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.
•
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. (Figure#49
Figure # 49
•
The condensate overflow protection sensor is
located in the drain pan of the unit and connected to
the 'COND' terminal on the UPM board. (Figure #49)
Figure # 50
Revised 07-17
UPM Board Factory Default Settings
TEMP
LOCKOUT
RESET
ALARM
TEST
UPM DIP SWITCH DEFAULT POSITION
lockout
reset
)
alarm
The UPM Board includes the following features:
•
ANTI-SHORT CYCLE TIMER: 5 minute delay on
break timer to prevent 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
unit simultaneously starting at the same time after
power up or after a power interruption, thus
avoiding creating large electrical spike.
•
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
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 lockout. In
order to exit hard lockout, power to the unit would
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 until the voltage is above 18 VAC
and ANTI-SHORT CYCLE TIMER (300 seconds) times
out. The unit will not go into a hard lockout.
26°F
2
Y
PULSE
NO
4
R
Cont
test
yes
8733942411 (2017/06)
Electrical | 19
2
Y
pulse
no
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