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COMPRESSOR STATUS
The TruVu provides a status input to monitor the compressor oper-
ation. The status is monitored to determine if the compressor sta-
tus matches the commanded state. This input is used to determine
if a refrigerant safety switch or other safety device has tripped and
caused the compressor to stop operating normally. If this occurs,
an alarm is generated to indicate the faulted compressor condition.
DEMAND LIMITING
The TruVu can accept 3 levels of demand limit from the BACnet
network. In response to a demand limit, the unit decreases its heat-
ing setpoint and increases its cooling setpoint to widen the range,
in order to immediately lower the electrical demand. You can con-
figure the temperature adjustment for both heating and cooling
and for each demand level. You can also set the response to a par-
ticular demand level to 0.
REMOTE DISABLE
Fire/Smoke Detector Input
The TruVu can read the status of a normally closed FSD contact
input to determine if a fire or smoke detector alarm is present. If
the controller determines an alarm condition is present, all heating,
cooling, and the fan are disabled. The switch is factory-set to Nor-
mally Closed and cannot be changed.
Shutdown Input
The TruVu controller has a shutdown input (software point)
which, when set to its Active mode causes the WSHP to safely
shutdown in a controlled fashion. Heating and cooling is disabled
after any minimum runtime conditions expire and the fan is dis-
abled after the fan-off timer expires. All alarms are reset but any
active alarm remains active. After the shutdown input transitions
from Active mode to Inactive, the TruVu restarts after the config-
ured power fail restart delay expires.
ALARMS
High Discharge Pressure (UPM Alarm)
The TruVu WSHP monitors the status of a high discharge pressure
fault condition via the serial port (S1). The fault condition is deter-
mined by the Unit Protection Module (UPM) included on all
WSHPs. The UPM monitors a high-pressure switch input and es-
tablishes a high-pressure fault when the discharge pressure ex-
ceeds 600 PSIG. Upon fault a 5-minute break is initiated (soft
lockout) and the compressor is disabled. The unit will automati-
cally restart after this time period. If the fault occurs 2 times (con-
figurable on UPM) within 60 minutes the UPM will put the unit
into hard lockout requiring manual reset. Manual reset can be ac-
complished remotely when the UPM is configured for the reset
method "Y" by remotely disabling the unit via the TruVu WSHP.
Low Suction Pressure (UPM Alarm)
The TruVu WSHP monitors the status of a low suction pressure
fault condition via the serial port (S1). The fault condition is deter-
mined by the Unit Protection Module (UPM) included on all
WSHPs. The UPM monitors a low-pressure switch input and es-
tablishes a high-pressure fault when the discharge pressure drops
below 40 PSIG. Upon fault a 5-minute break is initiated (soft lock-
out) and the compressor is disabled. The unit will automatically
restart after this time period. If the fault occurs 2 times (configu-
rable on UPM) within 60 minutes the UPM will put the unit into
hard lockout requiring manual reset. Manual reset can be accom-
plished remotely when the UPM is configured for the reset meth-
od "Y" by remotely disabling the unit via the TruVu WSHP.
Air Coil Freeze Alarm (UPM Alarm)
The TruVu WSHP monitors the status of an air coil freeze fault
condition via the serial port (S1). The fault condition is determined
by the Unit Protection Module (UPM) included on all WSHPs.
The UPM monitors the heating liquid line refrigerant temperature
and establishes a high-pressure fault if the temperature drops be-
low 26°F (configurable on UPM) for 30 seconds. Upon fault a
5-minute break is initiated (soft lockout) and the compressor is
disabled. The unit will automatically restart after this time period.
If the fault occurs 2 times (configurable on UPM) within 60 min-
utes the UPM will put the unit into hard lockout requiring manual
reset. Manual reset can be accomplished remotely when the UPM
is configured for the reset method "Y" by remotely disabling the
unit via the TruVu WSHP.
Water Coil Freeze Alarm (UPM Alarm)
The TruVu WSHP monitors the status of a water coil freeze fault
condition via the serial port (S1). The fault condition is determined
by the Unit Protection Module (UPM) included on all WSHPs.
The UPM monitors the cooling liquid line refrigerant temperature
and establishes a high-pressure fault if the temperature drops be-
low 26°F (configurable on UPM) for 30 seconds. Upon fault a
5-minute break is initiated (soft lockout) and the compressor is
disabled. The unit will automatically restart after this time period.
If the fault occurs 2 times (configurable on UPM) within 60 min-
utes the UPM will put the unit into hard lockout requiring manual
reset. Manual reset can be accomplished remotely when the UPM
is configured for the reset method "Y" by remotely disabling the
unit via the TruVu WSHP.
Condensate Overflow Alarm (UPM Alarm)
The TruVu WSHP monitors the status of a condensate overflow
fault condition via the serial port (S1). The fault condition is deter-
mined by the Unit Protection Module (UPM) included on all
WSHPs. The UPM monitors a condensate overflow switch and
upon fault puts the unit in a hard lockout condition, disabling the
compressor. The hard lockout condition requires manual reset.
Manual reset can be accomplished remotely when the UPM is
configured for the reset method "Y" by remotely disabling the unit
via the TruVu WSHP.
Brownout Alarm (UPM Alarm)
The TruVu WSHP monitors the status of a brownout fault condi-
tion via the serial port (S1).
Fire/Smoke Detector Alarm
The control monitors the voltage input to J1-9 to detect if a smoke
detector or fire detector NC contact has opened, indicating an
alarm condition. The control verifies the presence of 24 Vac on
this input. If the input opens at any time, an alarm is generated af-
ter 3 seconds and the equipment (fan, compressor, aux heat, and
damper) immediately shuts down.
Space Temperature Alarms
The control provides the ability to generate an alarm when the
space temperature exceeds the alarm setpoint. A separate occupied
hysteresis and fixed unoccupied high and low alarm setpoints are
provided. The control provides a 5-minute alarm delay during un-
occupied periods. During occupied periods, the control uses the
occupied temperature setpoint and applies the hysteresis value to
determine the alarm setpoints. When occupancy transitions from
unoccupied to occupied or the occupied temperature setpoints are
changed, causing an alarm condition to occur, the control automat-
ically calculates an alarm delay (equivalent to the configured de-
lay time in minutes/ ° F, multiplied by the temperature error, + 15
minutes). This prevents nuisance alarms when an occupancy
change occurs and allows time for the unit to correct an alarming
temperature condition.
Source Water Temperature Alarm
The control has 4 configurable alarm limits for source water tem-
perature. The control verifies that the water temperature is within
operating range (between high and low limits) for the specific op-
erating mode (heating or cooling) before energizing the compres-
sor. Once the compressor is started, the source water temperature
is further monitored to verify that it is within limits to insure suffi-
cient water is flowing through the coil. If the leaving water tem-
perature rises above or falls below the appropriate limits, and lasts
for more than 15 seconds, an alarm is generated and the compres-
sor shuts down.
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