Reznor ZQYRA Unit Installation Manual - Manual (Page 31)

Form I-ZQYRA P/N 260414R5, Page 31
8.3.1 Service Alarms
The unit has the ability to operate in a cripple mode to help limit the amount of down-
time of the system. Cripple mode operation is allowed to run until one of the following
four conditions is exceeded.
• The wheel discharge air temperature falls below the low temperature limit
setpoint ( Low Temp SP = 48°F/8.9°C); the wheel discharge air temperature
rises above the high temperature limit setpoint ( Hi Temp SP = 85°F/29.4°C); the
wheel discharge air dewpoint rises above the dewpoint high limit ( Hi Dewpt SP =
68°F/20°C); or the run time exceeds the cripple time setpoint (Cripple Time = 72
hours).
The system then shuts down and requires a manual restart. The cripple mode occurs
when one of the following alarms occur: a sensor failure alarm (Outside Air Temper-
ature, Energy Recovery Wheel Discharge Temperature, or Energy Recovery Wheel
Discharge Humidity); a Heat Pump General Alarm; a Unit Discharge Air Temperature
Failure Alarm; or a Reversing Valve Failure Alarm. If at any time the during cripple
mode operation the alarm returns to normal, the system will automatically return to the
normal operation mode, and active alarms will automatically be cleared and logged.
Sensor Failure: A specific alarm will be initiated when any of the sensors indicate
failure. Below is a list of the sensor failures and mode of operation during the failure.
During a service alarm condition, the system has three modes of operation. This helps
insure optimum performance, limited down time, and equipment protection. The modes
include restart, cripple, and shutdown.
Cripple Mode
Restart Mode The restart mode occurs when one of the following alarms occur: a fan failure alarm,
a low limit alarm, or a heat pump restart alarm. During the restart sequence the unit
mode shows “Restart”. During this condition, the time remaining before auto restart is
shown on the summary page and also on the restart alarm screen.
The restart sequence is as follows: The unit shuts down for 60 minutes. After the
restart timer has expired, the system restarts in normal mode. Resetting the alarm
through the unit interface module or power cycling the unit will clear the system restart
mode, and the unit will then restart in normal mode. The alarm(s) that caused the sys-
tem restart will be logged in the alarm screen under the alarm history menu.
Supply and Exhaust Air Fans Failure Alarm: The system monitors both the supply
fan and exhaust fan status using dedicated pressure switches for each fan. Upon a
command to start, the system allows 120 seconds ( FanFailureTimer = 120 seconds)
to prove operation. If fan operation does not prove via the airflow switch, the system
control will shut down the system and start the auto restart sequence. There is a spe-
cific alarm for the supply fan and another for the exhaust fan.
Low Limit Alarm: If the unit discharge air temperature (DAT) falls below the Low
Limit (freezestat) Setpoint ( LoLimitSP = 36°F/2°C) for more than the Low Limit Timer
( LoLimitTmr = 10 minutes), the controller shuts down the system, closes the outside
air damper, and starts the auto restart sequence.
The low limit sequence can be disabled by setting the Low Limit enable setpoint to
“No” ( LoLimitEn = Yes). NOTE: Changing the setpoint to “No” disables the low limit
sequence, and the unit will no longer shut down on low discharge air temperature.
Heat Pump Restart Alarm: This alarm occurs when the heat pump has been shut
down due to an alarm condition and the discharge air is outside the allowable limits.
The heat pump can be shutdown due to a heat pump general alarm, a reversing valve
failure, or the unit discharge air temperature sequence. For specific sequences for
each of the alarms listed, see the section “ Cripple Mode” below.
The second type of alarms is all of the maintenance alarms. Maintenance alarms are
alarms that only provide information such as dirty filter status, fan run time, and com-
pressor run time.
VOC/CO2 High Alarm (Monitor Only): When installed and set to monitor, the system
monitors the VOC/CO2 Level. Once the air quality has exceeded the setpoint limits
( CO2 Setpoint = 800 ppm / VOC Setpoint = 60%), the system will initiate a specific
alarm. The unit will remain in alarm until the air has dropped below the alarm dead-
band. See specific occupancy control type when sensor is used for on/off control.