Alarms - Carrier VAV Zone II Installation And Startup Manual

Learning Adaptive Optimal Start – This function gradually adjusts the unoccupied setpoints over a specified
period of time to achieve the occupied setpoint by the time scheduled occupancy begins. This learning adaptive
algorithm uses the learned heating capacity and learned cooling capacity values to calculate the effective
setpoints prior to the occupied start time. The algorithm calculates a learned cooling and heating capacity during
the previous unoccupied time. Set the Learning Adaptive Optimal Start recovery period from 1 to 4 hours in
Optimal Start. When the Learning Adaptive Optimal Start routine runs, adjustments are based on the color that is
achieved when occupancy begins. Adjustment amounts are defined in the thermographic color fields located
directly above the Effective Setpoints graph under Setpoints.
BAS On/Off – This function allows third party control of the controller occupancy. Occupancy Schedules must be
set to Disable to use this function. When set to Occupied or Unoccupied, Optimal Start is automatically disabled.
For additional information on ZS Sensor occupancy and override settings, see Maintenance (page 89) Points and
Properties.

Alarms

Space Temp Sensor Alarm – The VAV 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 setpoints are determined from the configurable Occupied Alarm Hysteresis (5 °F
[2 °C) default) which is subtracted from the configured occupied heat and added to the configured occupied cool
setpoints. If the space temperature rises above or falls below this value and the condition lasts for more than 15
minutes, an alarm is generated. 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 immediate alarm condition, the controller automatically calculates an additional alarm
delay equal to 10 minutes for each degree of change. This additional delay is added to the 15 minute fixed delay
and allows the space temperature to recover and achieve the new setpoints, preventing unnecessary alarms. The
space temperature alarm returns to normal when the space temperature again falls between the current mode's
alarm 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°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 Optional Ctrl Type is set to RH Control (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 equal to 5 minutes for each % RH of
change. This additional delay is added to the 15 minute fixed delay and allows the space relative humidity to
recover and achieve the new setpoints, preventing unnecessary alarms.
VAV Zone II Controllers
Installation and Start-up Guide
53
Sequence of operation
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