Carrier CRECOMZR085A00 - Start-Up and Operation; Cooling with Economi$Er X; Heating with Economi$Er X

19
START-UP AND OPERATION
Cooling with EconoMi$er
®
X
For Occupied mode operation of EconoMi$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
12 for Damper Position Control.
During Occupied mode operation, indoor fan operation will be
accompanied by 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
thermostat. Outside air damper position will be closed or
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 mixed air
temperature. Default mixed air temperature is 53°F, with a range
of 38°F to 70°F. Compressor will not run.
Should 100% outside air not be capable of satisfying the space
temperature, space temperature will rise until Y2 is called for. The
economizer control will call for compressor operation. Dampers
will modulate to maintain MAT at set point concurrent with
Compressor 1 operation. The “Low T Lock” setting (default 32°F)
will lock out compressor operation when outside air temperature
is below setpoint.
When space temperature demand is satisfied (thermostat Y1
opens), the dampers will return to Minimum Damper position if
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
dampers open above the EXH1 SET setpoint and will be
de-energized as the dampers close below the EXH1 SET setpoint
(for single speed unit).
Damper movement from full closed to full open (or vice versa)
will take between 1-1/2 and 2-1/2 minutes.
Heating with EconoMi$er
®
X
During Occupied mode operation, indoor fan operation will be
accompanied by 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 DCV demand is received.
When the room temperature calls for heat (W1 closes), the heating
controls are energized.
Table 12 — 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-L MIN POS-L MIN POS-H MIN POS-H
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