Honeywell CVL4022ASVAV1 Engineering Manual page 103

OverridePriority
The controller uses a Last-in-Wins scheme to determine
effective override state if override is done both from the wall
module as well as from the network. The last command
received from nviManOcc determines the effective override
state.
Occupancy sensor
The digital input for an occupancy sensor provides the
controller with a means to enter an energy-saving Standby
mode whenever there are no people in the room. The control
behavior in response to occupancy detection can be
configured using nciOccSensorOp to one of the the following
3 options:
UnoccupiedCleaningCrew: When scheduled to be unoccupied
and the occupancy sensor is active, controller switches to
standby for the comfort of the cleaning crew.
ConferenceRoom: When scheduled to be unoccupied
controller stays unoccupied independent of the occupancy
sensor activity. During scheduled occupancy, occupancy
sensor changes mode between standby and occupied.
UnoccupiedTenant: When scheduled to be unoccupied and
the occupancy sensor is active, controller switches to
occupied mode for the comfort of the tenant.
Window Sensor
The digital input for a window contact provides the algorithm
with a means to disable its temperature control activities if
someone has opened a window or door in the room. When a
window is detected to be Open, the box damper is
commanded to a configured percentage of maximum CFM
(m3h) air flow via nciFlowSP.WindowOpen. Normal
temperature control resumes when the window closes.
Continuous Unoccupied Mode
(conventional wall modules)
This mode is entered when a wall module is configured with a
bypass button that was pressed for four to seven seconds,
causing the wall module LED to blink. This mode can also be
entered via a network command (nviManOcc set to
Unoccupied). If the controller is in this mode, it reverts to the
Unoccupied Setpoints and control. The controller remains in
this mode indefinitely or until the bypass button is pressed to
exit the mode or a network command is sent to clear the
mode.
Share Wall Module
If one or more terminal units serve a common area, and it is
specified (or desired) to use a single temperature sensor for
these boxes, the Share Wall Module option can be configured.
The operation of the satellite controllers follows the
temperature control and modes of the controller with the
temperature sensor module. For example, this includes
Temperature Setpoints and Occupied/Unoccupied/Standby/
Bypass modes. This can also be used if there is a need to
reprogram multiple satellite controllers based on flexible floor
plans. Each controller is fitted with a wall module and the units
configured as a ShareWallModule with a valid nviShare
network connection respond as satellites of the master
controller providing nvoShare data.
Night Purge
If a terminal unit is put into the Night Purge mode, the
controller performs the following functions (It):
• Disables the temperature control loop.
• Overrides the flow control loop.
• Controls a damper to a configured percentage of maximum
CFM (m3h) air flow (PurgeDmprPos).
• Enables terminal fan.
Morning Warm-Up
A Morning Warm-Up cycle commands the controller to open
its VAV box to a preselected position or reverse acting
temperature control to allow the conditioned space to warm
up. On boxes with reheat, the reheat can be configured to be
either enabled or disabled during morning warmup. See
nciHeat. MornWarm
Smoke Control
The controller supports three smoke-related modes,
Pressurize, Depressurize and Purge. When the controller is
placed in one of these three modes via nviEmergCmd, the box
damper is commanded to a fixed position specified in a
separate Setpoint (nciFlowSP) for each mode, and the
temperature control function is disabled.
Demand Limit Control
When a high-electrical-demand signal is received via the Lon
network, the controller applies a setpoint shift to the current
PID error value (nviDlcShed). This has the effect of bumping
the temperature control point to save energy. This offset
bumps the cooling control point upward, and bumps the
heating control point downward. When the demand limit signal
is deactivated, the effective temperature control setpoint
returns to the normal value with a 30 minute ramp.
Start-Up and actuator synchronization
Upon initial start-up or on a restart after power failure, the
controller can be configured to drives its actuators open or
closed after a configurable startup delay. This allows different
controllers to go through different time delays to assure
smooth air handling unit start-up, minimizing air distribution
problems.
CO2 Ventilation
When a CO2 sensor input is available, the minimum airflow
setpoint can be reset automatically by the controller based on
configurable CO2 setpoint limits. A configurable fraction of the
maximum flow setpoint is automatically added to the minimum
airflow setpoint based on the sensed CO2 value thereby
improving indoor ventilation and air quality.
Automatic Heat-Cool changeover based on
SupplyTemperature
When a supply temperature input is configured and a valid
value is available, the controller can automatically switch
between heat mode and cool mode based on the supply
temperature. When the supply temperature is greater than 75
Deg F, the control switches to heat mode. If the supply
temperature is less than 70 DegF, then the control can
automatically switch between cool mode and reheat mode
based on the space temperature value as per the following
rule:
103 31-00083—02