Data Sheet for Product

Sequence of Operation
General
This example configuration uses a chilled water coil for cooling and dehumidification, a hot
water heating coil, and an outdoor air damper for cooling and ventilation. The Predator
monitors the temperature and humidity in the room and compares them to selected setpoints.
As the monitored conditions change, the control algorithm operates the heating and cooling
equipment to efficiently maintain the specified room setpoints.
Occupied Control
The fan may be configured to run throughout the occupied periods, or to cycle with need for
heating or cooling. The outdoor air damper opens to at least the minimum ventilation setting.
Cooling
The Predator calculates the discharge air temperature that keeps the room temperature at the
cooling setpoint. When outdoor conditions permit free cooling, the Predator sequences the
outdoor air damper and the chilled water coil to maintain the discharge of the unit at the
temperature that meets the load in the space. When outdoor conditions do not allow free
cooling, the Predator sets the outdoor damper at the ventilation minimum and operates the
chilled water coil to maintain the discharge temperature at setpoint.
Heating
The Predator calculates the discharge air temperature that keeps the room temperature at the
heating setpoint. The Predator operates the hot water valve to maintain the discharge from
the unit at the calculated temperature setpoint. The outdoor damper stays at the ventilation
minimum.
Dehumidifying Mode
When the humidity in the space goes above the setpoint, the Predator opens the cooling coil
valve, sets the outdoor damper at the ventilation minimum, and operates the hot water valve to
temper the discharge from the unit and prevent overcooling the space. When the humidity in
the space drops (below the level defined by the space humidity setpoint minus a deadband),
the Predator returns to the heating or cooling mode.
Standby Control
Spaces that are not occupied on a routine basis (conference rooms, etc.) can be placed into
standby mode during normally scheduled occupancy times. This saves energy by applying
conservative setpoints and eliminating unnecessary ventilation.
Unoccupied Control
General
During unoccupied periods, the fan only runs when needed for heating, cooling, or
dehumidifying.
The Predator may be configured to individually apply or lock out each heating and cooling
device (hot water valve, OA damper, chilled water valve) during unoccupied periods.
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Document No. 588-153