Alarms - Carrier VVT Zone II Installation And Startup Manual

Alarms

Space Temp Sensor Alarm – The VVT Zone II monitors each space temperature sensor and the network input for
space temperature. If no valid space temperature value is available, the controller generates an alarm and
disables all local heating or cooling. The controller modulates the damper to the minimum heat, minimum cool, or
ventilation position based on the air source mode. Normal operation resumes when the controller detects a valid
sensor value.
Space Temperature Alarm – The controller generates an alarm if the space temperature exceeds the alarm
setpoint. The occupied alarm setpoint is the configurable Occupied Alarm Hysteresis (5 °F [2.78 °C] default)
subtracted from and added to the configured occupied heat and cool setpoints. The configurable unoccupied high
and low alarm setpoints have a fixed 10 minute alarm delay. When a transition from unoccupied to occupied
occurs or the occupied temperature setpoints are changed, causing an alarm condition, the controller
automatically calculates an alarm delay of 10 minutes for each degree of change. The delay prevents unnecessary
alarms and gives the zone time to correct the alarm condition. The alarm returns to normal when the space
temperature goes between the current mode's setpoints.
Supply Air Temperature Alarm – The controller generates an alarm if the SAT exceeds the configured High SAT
Alarm Limit (120°F [48.9°C] default) or falls below the Low SAT Alarm Limit (45°F [7.2°C] default) for more
than 5 minutes. The hysteresis for return to normal is 3 °F (1.6 °C) . The High SAT Alarm Limit should be set to
a value at least 15 °F (8.3 °C) above the Maximum Heating SAT or the maximum discharge temperature from
the air source, whichever is greater.
Space Relative Humidity Alarm – If a Space Relative Humidity (RH) sensor is installed, the controller generates an
alarm if the sensor's value exceeds the Occ High RH Alarm Limit (100% rh default) or the Unocc High RH Alarm
Limit (100% rh default). The controller provides a 30-minute alarm delay during unoccupied periods. During
occupied periods, the controller uses the Occ High RH Alarm Limit. When a transition from unoccupied to
occupied occurs or the occupied high alarm limit is lowered causing an alarm condition to occur, the controller
automatically calculates an alarm delay of 5 minutes per %RH multiplied by the amount of the change. The delay
prevents unnecessary alarms and gives the zone time to correct the alarm condition. The hysteresis for return to
normal is 3% RH.
Indoor Air Quality Alarm – If a CO
if the sensor's value exceeds the Occupied High CO2 Alarm Limit. When a transition from unoccupied to occupied
occurs, or if the occupied alarm limit is changed to a value that causes an alarm condition to occur, the controller
automatically calculates an alarm delay based on the error from setpoint (15 minutes minimum, 4 hours
maximum). The delay prevents unnecessary alarms and gives the zone time to correct the alarm condition. To
disable the IAQ alarm, set Occupied High CO2 Alarm Limit to 0. The default value is 1100ppm. The hysteresis for
return to normal is 100ppm.
Filter Alarm – For series or parallel fan-powered terminals, the controller monitors the accumulated hours of fan
operation and generates an alarm when the Filter Runtime hours exceed the configured Filter Service Alarm
Timer limit. The default value is 0 hours which disables the alarm. The alarm can be reset by setting Reset Filter
Alarm to On or resetting the configured alarm limit to 0 hours.
Airside Linkage Alarm – The slave zone controller generates an alarm if it does not receive linkage information for
5 minutes. If the controller is the VVT Master, it generates an alarm if it does not communicate with its air source
for 5 minutes. A return-to-normal is generated after successful Linkage communication resumes.
VVT Zone II Controller
Installation and Start-up Guide
sensor is installed, the controller generates an alarm during occupied periods
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Sequence of operation
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