Honeywell CVL4022ASVAV1 Engineering Manual page 104

If the controller is in cool mode and if the space temperature is
less than the effective heat setpoint and is also less than
(effective cool setpoint - 1.0) then the controller switches to
reheat mode. While in reheat mode if space temperature is
greater than the effective cooling setpoint and also greater
than the (effective Heat setpoint + 1.0) then the controller
switches to cool mode.
Air Flow Control Sequences of Operation
The primary function of the temperature-control application is
to regulate the quantity of supply air delivered to the space to
control the space temperature. The algorithm assumes there
is cold air in the duct; therefore, as the box damper is opened
wider, the space becomes cooler. The damper is commanded
between configurable minimum and maximum positions for
pressure dependant control. For pressure independent
control, the damper is commanded between configurable
minimum and maximum flow setpoints. When a flow sensor
input is not available, control automatically switches to
pressure dependant control. Damper/airflow control is also
coordinated with CO2 sensor value when available to maintain
the required indoor ventilation.
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FlowTracking
The controller can be configured for flow tracking. This feature
is used to balance the flow between several input vav boxes
and one exhaust vav box in a room. Typically, the exhaust box
controller is configured as the flow tracking controller.
Temperature control is disabled in flow tracking mode and the
controller commands the damper to achieve a flow setpoint
that is calculated by adding a configured flow offset value to
the supply flow of all the input vav boxes. See nviFlowTrack
and nciFlowLoop.Type.
Flow Tracking Application Notes:
1. Flow tracking is intended for noncritical, slow respond-
ing commercial building zone pressurization control
sequences. This means that average pressurization can
be maintained if disturbances are slow acting, but fast
disturbances may result in temporary short term imbal-
ances. Do not apply the VAV Flow Tracking option in life
safety or industrial environments such as clean rooms,
fume hoods, or bio hazard control.
2. Flow tracking requires high resolution air flow damper
actuators. Floating actuators are recommend.
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