Installation Instructions

Sequence of Operation
Occupied Control
General
The supply fan starts slowly and runs throughout the occupied mode. A PID control loop
continually adjusts the fan capacity to maintain the duct static pressure at setpoint as loads
vary in the zones. The duct pressure setpoint may be an adjustable constant, or may be
varied automatically by another node to minimize energy consumption.
Ventilation Control Ventilation (DCV)
During occupied mode, the outdoor air damper opens to the design ventilation setting and
stays open. When Demand Controlled Ventilation (DCV) is implemented, the ventilation
setting may be automatically adjusted from internally in the Predator or by another node to a
value appropriate for the demand. The Predator DCV function is adjustable, while the
ventilation demand value comes from another node.
The supply air temperature setpoint may be adjusted manually or varied according to an
adjustable built-in reset function.
Discharge Temperature Control
Hot Water Option
When free cooling is available, the heating coil valve, outdoor air damper, and stages of DX cooling
operate sequence to maintain discharge air temperature setpoint. The outdoor air damper does not
close beyond the current ventilation setting. When free cooling is unavailable, the outdoor air damper
goes to the current ventilation setting; the heating coil valve modulates and stages of cooling operate
in sequence to maintain discharge air temperature setpoint.
Staged Heat Option
When free cooling is available, the heat stages, outdoors air damper, and stages of cooling operate in
sequence to maintain discharge air temperature setpoint. The outdoor air damper does not close
beyond the current ventilation setting. When free cooling is unavailable, the outdoor air damper goes
to the current ventilation setting; the heat stages and stages of cooling operate in sequence to
maintain discharge air temperature setpoint.
Unoccupied Control
General
During unoccupied periods, the air handler is normally off. The outdoor damper is closed and
the DX equipment is off. The optional hot water coil valve may be forced closed, or it may
operate to maintain unit temperature above freezing. Optional staged heat stages are turned
off.
The Predator may run the air handler intermittently to provide heating or cooling in response to
demand from the associated unoccupied zone controllers.
Unoccupied Cooling Mode
The air handler starts in response to a cool or pre-cool command from the network or
measured zone temperature above the unoccupied setpoint. The Predator modulates the
supply fan capacity to maintain measured duct pressure at the duct static pressure setpoint. If
free cooling is not available, the outdoor air damper closes fully. Mechanical cooling may be
locked out during unoccupied periods.
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Document No. 588-150