22
OPERATION
Cooling, Unit with EconoMi$er X System
For Occupied mode operation of EconoMi$er X system, there
must be a 24-v signal at terminals R and OCC (provided through
PL6-3 from the unit’s IFC coil). Removing the signal at OCC
places the EconoMi$er X control in Unoccupied mode. See Table
13 for damper position control.
During Occupied mode operation, indoor fan operation will be
accompanied by the economizer dampers moving to Minimum
Position setpoint for ventilation. If indoor fan is off, dampers will
close. During Unoccupied mode operation, dampers will remain
closed unless a Cooling (by free cooling) or DCV demand is
received.
When free cooling using outside air is not available, the unit
cooling sequence will be controlled directly by the space thermo
-
stat. Outside air damper position will be closed or set to minimum
position as determined by Occupancy mode and fan signal.
When free cooling is available as determined by the appropriate
changeover command (dry bulb, outdoor enthalpy, differential dry
bulb or differential enthalpy), a call for cooling (Y1 closes at the
thermostat) will cause the economizer control to modulate the
dampers open and closed to maintain the unit supply air
temperature. Default supply temperature is 53°F, with a range of
38°F to 70°F. The compressor will not run.
Should 100% outside air not be capable of satisfying the space
temperature, space temperature will rise until Y2 is closed. The
economizer control will call for compressor operation. Dampers
will modulate to maintain SAT at set point concurrent with
Compressor 1 operation. The “Low T Temp” setting (default
32°F) will lock out compressor operation.
When space temperature demand is satisfied (thermostat Y1
opens), the dampers will return to Minimum Damper position if
the indoor fan is running or fully closed if fan is off.
If accessory power exhaust is installed, the power exhaust fan
motors will be energized by the economizer control as the damp
-
ers open above the EXH1 SET setpoint and will be energized as
the dampers close below the EXH1 SET setpoint.
Damper movement from fully closed to fully open (or vice versa)
will take between 1-1/2 and 2-1/2
minutes.
Heating with EconoMi$er X System
During Occupied mode operation, indoor fan operation will be
accompanied by economizer dampers moving to Minimum
Position setpoint for ventilation. If the indoor fan is off, dampers
will close. During Unoccupied mode operation, dampers will
remain closed unless a DCV demand is received.
When the room temperature calls for heat (W1 closes), the heating
controls are energized.
Table 13 —
Damper Position Control, 2-Speed Fan Motor, Economizer Cooling Not Available
INPUT
VOLTAGE
OCC
0-V
24-V
24-V
24-V
24-V
Y1
0-V
0-V
24-V
24-V
0-V
Y2
0-V
0-V
0-V
24-V
0-V
W1
0-V
0-V
0-V
0-V
24-V
Supply Fan Motor
Speed
OFF
LOW
LOW
HIGH
HIGH
DAMPER POSITION
No CO
2
Sensor
CLOSED
MIN. POS.
MIN. POS.
MIN. POS.
MIN. POS.
W/ CO
2
Sensor
CLOSED
FROM VENTMIN L
TO
VENTMAX L
FROM VENTMIN L
TO
VENTMAX L
FROM VENTMIN H
TO
VENTMAX H
FROM VENTMIN H
TO
VENTMAX H
