Safety Devices and the UPM Controller Overview
• FREEZE SENSORS:
Table 11 Freeze Sensors
Freeze
Sensor
Location
Default
Freeze-Limit
Setting
Fault Code
(Number of
Flashes)
1 First-Stage Water Coil
25°F
5
2 First-Stage Air Coil 8
3 Second-Stage Water Coil 9
4 Second-Stage Air Coil 10
The UPM controllers constantly monitor temperature
readings from all freeze sensors. If a temperature reading
drops below or remains at the freeze-limit trip for 120
seconds, the controller will shut the compressor down and
enter into a soft-lockout condition. The status LED on the
UPM board corresponding to the tripped sensor will be
active. (
Refer to Fig. 8 and Fig. 9, item [6].) And the alarm
contact will be active on the first-stage UPM. (
Refer to Fig.
8, item [17].) The status LED will blink the fault code. The
LED will flash the code associated with this alarm condition
three times. If this alarm occurs two times (or four if DIP
switch position “1” is set to “ON”) (Refer to Fig. 13)(See
Table 9) within an hour, the UPM controller will enter into a
hard-lockout condition.
The default setting for the freeze limit trip is 25°F for all freeze
sensors. However, for Freeze Sensors 1 and 3 this can be
changed to 15°F by flipping the DIP switch position “5” to
“ON.” (Refer to Fig. 13.) The freeze limit trip should only
be changed to 15°F when a closed loop system with
appropriate antifreeze mixture is used. Freeze Sensor 1 is
controlled by the DIP switch on the First-Stage UPM board
(
Refer to Fig. 8, item [10] for DIP switch location.). Freeze
Sensor 3 is controlled by the DIP switch located on the
Second-Stage UPM board (
Refer to Fig. 9, item [10] for
DIP switch location.).
NOTICE
If the unit is employing a fresh water system (no antifreeze
protection), it is extremely important to have the Freeze 1 DIP
switch position “5” set to OFF to shut down the unit at the
appropriate leaving water temperature and protect your heat
pump from freezing if a freeze sensor is included.
• CONDENSATE OVERFLOW SWITCH: All EC units
are equipped with a condensate overflow switch that turns
OFF the unit in the event that water in the drain pan
surpasses the acceptable limit. Once water touches the pin
on the sensor, the unit immediately enters a hard lockout
condition that requires a manual lockout reset. This will occur
even if there is no call for compressor operation.
• INTELLIGENT RESET: If a fault condition is initiated,
the five-minute delay on break time period is initiated and the
unit will restart after these delays expire. During this period
the fault LED will indicate the cause of the fault. If the fault
condition still exists or occurs two or four times (depending if
the Lockout DIP switch position “1” is set to "OFF" or
"ON")(See Table 9) before 60 minutes, the unit will go into
a hard lockout and requires a manual lockout reset.
• LOCKOUT RESET: The method to exit a hard lockout
depends of the Reset DIP switch setting:
— To clear a hard lockout when the Reset DIP switch
position “2” is set to “OFF” (Y), power can be cycled
OFF then back ON either at the unit’s thermostat or at
the circuit breaker.
— To clear a hard lockout when the Reset DIP switch
position “2” is set to “ON” (R), power must be cycled
OFF then back ON at the circuit breaker (not at the
thermostat).
(Refer to Fig. 13.)(See Table 9.)
The blower motor will remain active during all lockout
conditions.
12.5 Leak Detection System
The refrigerant leak detection system is comprised of two
components: the A2L refrigerant sensor and the UPM board. The
sensor continually samples the air and if the concentration of
refrigerant detected is higher than the preset threshold
(15% LFL), it sends a signal to the UPM, which then switches OFF
the comp
ressor and turns ON the blower. The compressor
remains OFF until the saturation level is below (15%LFL) and the
power is cycled in order to restore normal operations. If the A2L
sensor is connected to the UPM, it must always remain
connected. If communication is lost, the UPM enters a refrigerant
leak hard lockout fault and energize the alarm contact. To test
that the communication between the sensor and board is active,
the sensor can be disconnected from the UPM, which should
simulate a fault. The A2L sensor for the refrigerant leak detection
system must only be replaced with the part specified on the
spare parts list.
WARNING
The Leak Detection System requires that the unit remains
powered except when servicing.
30 |
EC Series Heat Pumps — 8733841499 (2024/05)
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