Carrier WeatherExpert 50LC14 Installation Instructions Manual page 59

Table 17 — W7220 Input/Output with Demand Controlled Ventilation (IDCV)
INPUTS
DEMAND OUTSIDE AIR
CONTROLLED GOOD TO
VENTILATION ECONOMIZE
No
Below set
Yes
No
Above set
Yes
* Fan Speed for reference only; not an input or output function of the W7220.
† See Menu ADV SETUP —> 2SP FAN DELAY for details.
** See Menu ADV SETUP —> STG# DLY. With Stage 3 enabled, control can turn on second stage cooling Y2-O after delay if the call for Y2-I has not
been satisfied.
Cooling, Unit with EconoMi$er
For Occupied mode operation of the EconoMi$er X control, there
must be a 24-v signal at terminal G at the unit's Integrated Staging
Control Board from the thermostat; supply fan motor will start and
run in Low Speed. The signal at G is connected to W7220 input
OCC, placing the EconoMi$er X control in Occupied mode; the
economizer actuator is commanded open to the MIN POS L venti-
lation position. Removing the signal at OCC places the
EconoMi$er X control in Unoccupied mode; the economizer actu-
ator is driven back to full-closed position.
When free cooling using outside air is not available, the unit cool-
ing sequence will be controlled directly by the space thermostat.
Thermostat call for Stage 1 Cooling energizes ISC terminals G
and Y1; supply fan motor starts and runs in Low Speed. The Y1
demand is received at W7220 terminal Y1-I. Outside air damper
position will be at MIN POS L. W7220 output Y1-O is energized;
first stage mechanical cooling starts.
As space temperature falls and space cooling load is satisfied, the
thermostat will remove its call for first stage cooling; ISC terminal
Y1 call is removed. The W7220 input Y1-I is removed; output
Y1-O is de-energized, stopping first stage cooling.
When ISC terminal Y1 is de-energized, terminal G may remain
energized, indicating Continuous Fan operation. The supply fan
motor will continue to run in Low Speed. W7220 input OCC re-
mains energized; the outside air damper remains in MIN POS L. If
ISC terminal G is also de-energized with Y1, indicating AUTO
Fan operation, then the supply fan motor will stop. The W7220 in-
put at OCC is removed; the outside air damper closes.
If the space temperature continues to rise, the thermostat will call
for second stage cooling; ISC terminal Y2 is also energized. The
supply fan motor shifts to MED Speed. Outside air damper posi-
tion will remain in MIN POS L, second stage cooling starts.
As space temperature falls, the thermostat will remove its call for
second stage cooling; ISC terminal Y2 call is removed. The sup-
ply fan motor shifts back to Low Speed. The outside air damper
remains at MIN POS L and the ISC board will stop second stage
mechanical cooling.
FAN
SPED
Y1-I Y2-I
(REF)*
Y1-O/1ST Y2-O/2ND
Off Off Low
On Off Low 24 V/On
On On High 24 V/On
Off Off Low
On Off Low
On On High
24 V/On
Off Off low
On Off Low 24 V/On
On On High 24 V/On
Off Off Low
On Off Low
On On High
24 V/On
X without CO Sensor
®
2
MECHANICAL
COOLING STAGE
OCC YES
0 V/Off 0 V/Off VENTMIN L
0 V/Off VENTMIN L
24 V/On VENTMIN H
0 V/Off 0 V/Off VENTMIN L
Modulating: VENTMIN L to
0 V/Off 0 V/Off
Full — Open
2SP
Modulating: VENTMIN H
Delay † 0 V/Off**
to Full — Open
Modulating: VENTMIN L to
0 V/Off 0 V/Off
VENTMAX L
Modulating: VENTMIN L to
0 V/Off
VENTMAX L
Modulating: VENTMIN H
24 V/On
to VENTMAX H
Modulating: VENTMIN L to
0 V/Off 0 V/Off
VENTMAX L
Modulating: VENTMIN L to
0 V/Off 0 V/Off
Full — Open
2SP
Modulating: VENTMIN H
Delay 0 V/Off**
†
to Full — Open
If the space temperature continues to rise, the thermostat will call
for third stage cooling; ISC terminal Y-3 is also energized. The
supply fan motor shifts to High Speed. The outside air damper po-
sition will shift to MIN POS H, third stage cooling starts.
As space temperature falls, the thermostat will remove its call
for third stage cooling; ISC terminal Y3 call is removed. The
supply fan will shift to Medium Speed. The outside air damper
position is repositioned to MIN POS L and stop third stage me-
chanical cooling.
When free cooling is available as determined by the appropriate
changeover command (outdoor dry bulb, outdoor enthalpy, differ-
ential dry bulb or differential enthalpy), a space thermostat call for
Stage 1 Cooling energizes ISC terminals G and Y1; supply fan
motor starts and runs in High Speed. The G demand is received at
W7220 input OCC; outside air damper moves to MIN POS L. The
Y1 demand is received at W7220 terminal Y1-I. The W7220
economizer control will modulate the outside air damper open and
closed to maintain the unit cooling supply air temperature at set-
point MAT SET (default 53°F [12°C]). Compressor will not run.
During free cooling operation, a supply air temperature (SAT)
above MAT SET will cause the outside air damper to modulate
between MIN POS L setpoint and 100% open. As SAT decreas-
es and approaches setpoint MA LO SET (default 45°F [7°C]),
the outside air damper will maintain at the MIN POS L setting.
With SAT below MA LO SET, the outside air damper will be
closed or at minimum (see FREEZE POS). When SAT rises to
MA LO SET plus 3°F, the outside air damper will re-open to
MIN POS L setting.
Should 100% outside air not be capable of satisfying the space
cooling load, space temperature will rise and the thermostat will
call for second stage cooling; ISC terminal Y2 is also energized.
The supply fan motor remains at High Speed. Outside air damper
position will remain at MIN POS L, starting second stage cooling
(Compressor 1 operation). Damper will modulate to maintain SAT
at MAT SET concurrent with Compressor 1 operation.
59
OUTPUTS
OCCUPANCY
OUTSIDE AIR DAMPER POSITION
OCC NO
Closed
Closed
Closed
Closed
Modulating: Closed to Full —
Open
Modulating: Closed to Full —
Open
Closed
Closed
Closed
Closed
Modulating: Closed to Full —
Open
Modulating: Closed to Full —
Open