Reznor ZQYRA Unit Installation Manual - Manual (Page 33)

Form I-ZQYRA P/N 260414R5, Page 33
Unless noted in the specific sequences below, when a shutdown alarm occurs a man-
ual restart is required to return the unit to normal operation. Manual restart can be done
by resetting the system shutdown alarm from the unit interface module, by cycling
power to the unit, or by restarting through a field-supplied Building Automation System.
Shutdown Digital Input (DI-5) Alarm - Whenever the system controller sees the shut-
down contact go into the alarm condition (open), the controller will initiate a specific
alarm to indicate alarm condition and shut down the unit. The unit will remain off and
in the alarm condition until the shutdown contact alarm condition is cleared (closed).
Once the alarm is cleared, the unit will automatically clear the alarm and restart the
system in normal operation.
Cripple Mode Time Exceeded Alarm - If the unit exceeds the allowed cripple mode
operation time limit, the unit will shut down and will initiate a specific alarm to indicate
alarm condition. The unit mode shows “Shutdown” on the summary page. For more
detailed sequence, see the “Cripple Mode” operation sequence. Once the unit is in
this mode, the unit must be manually restarted. The alarm(s) that caused the system
shutdown will be logged in the alarm screen under the Alarm History Menu.
Multiple Restart Shutdown Alarm - The system is allowed to go through the restart
sequence a fixed number of times over a 24 hour period. Once the unit has gone
through the auto restart limit ( Auto Restart = 3), the system controller locks the sys-
tem out. The unit mode shows “Shutdown” on the summary page. Once the unit is in
this mode, the unit must be manually restarted. The alarm(s) that caused the system
shutdown will be logged in the alarm screen under the Alarm History Menu.
Multiple Sensor Failure - If at any time the unit has multiple sensor failures (sensor
failures are listed under the Cripple Mode Operation Sequence Mode), the unit will
shut down and issue a specific alarm to indicate alarm condition and the unit mode
shows “Shutdown” on the summary page. Once the unit is in this mode, the unit must
be manually restarted. The alarm(s) that caused the system shutdown will either still
be active in the active alarm screen or will be logged in the alarm screen under the
Alarm History Menu.
High Outside Air Temperature Limit Alarm - If the outside air temperature is above
High Outside Air Alarm setpoint ( Hi OAT Setpoint = 115°F/ 46°C), the system will shut-
down the unit and initiate a specific alarm. The unit will remain off until the outside air
temperature is below the outside air temperature high lockout setpoint by the High
Outside Air Alarm Deadband ( Hi OAT Deadband = 5°F/3°C)
Wheel Defrost Alarm - The unit has a builtin wheel defrost sequence to prevent dam-
age to the wheel. If the wheel discharge temperature falls below the Energy Recovery
Wheel Discharge Air Temperature ( ERW DAT Limit = 32°F/0°C) and the humidity is
above the Energy Recovery Wheel Discharge Air Humidity ( ERW DAH Limit = 90%)
for more than High Limit Timer ( Limit Timer = 10 minutes), the system shall enable
defrost control.
The first stage of defrost control is to activate the preheat coil (if available). After the
stage one timer ( Stage1Timer = 10 minutes) has elapsed, if the conditions do not
rise above the setpoints, the unit will shutdown. If no preheat is available, the unit will
shutdown. The system will automatically restart after one of the defrost auto reset
conditions are met.
• When the unit has been off for the minimum defrost time ( Time Reset = 6 hours)
• When the outside air temperature rises above the reset temperature ( OAT Reset =
34°F/1°C).
If three alarms occur within a 24 hour period, the unit will lockout and require a manual
restart.
8.3.2 Maintenance
Alarms
Maintenance alarms only provide information that can be used in helping to maintain
the equipment to insure optimum performance. The filter alarm is activated only when
the option is ordered. Run time alarms are built-in to the system but are disabled by
default. They can be enabled through the unit interface under the “Service” / ”Run
Times” menus.
Filter Alarm - The system monitors the filter pressure using a dedicated pressure
switch. Adjusting the switch trip pressure is done manually at the pressure switch (See
Paragraph 8.8.). Upon a switch closure, the system initiates a specific alarm to indicate