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As space temperature falls, the thermostat will remove its
call for second stage cooling; CTB terminal Y2 call is
removed. The supply fan motor shifts back to Low Speed.
The W7220 input Y2- - I is also removed; the outside air
damper limit is repositioned to between MIN POS L and
100% open. Output Y1- - O is de- - energized, stopping first
stage mechanical cooling. As space temperature continues
to fall and space cooling load is satisfied, the thermostat
will remove its call for first stage cooling; CTB terminal
Y1 call is removed. The W7220 input Y1- - I is removed;
free cooling mode ends. Outside air damper will move to
MIN POS L if supply fan remains in operation (CONT
FAN) or to closed if supply fan stops (AUTO FAN).
Compressor
Low
Compressor Low Temperature Lockout (setpoint LOW T
LOCK, default 32_F (0_C)) will block compressor operation
with economizer operation at outdoor temperature below this
setpoint.
Power Exhaust — If accessory power exhaust is
installed, the power exhaust fan motors will be energized
by the economizer control as the dampers open above the
setpoint EXH1 SET L during Low Speed operation or
EXH1 SET H during High Speed fan operation. The
EXH1 output will be de- - energized as the dampers close
below the EXH1 setpoint value.
Damper movement from full closed to full open (or vice
versa) will take approximately 1- -
Stage 3 Cooling
The W7220 controller also is capable of calling on a third
stage of cooling by initiating the second stage of
mechanical cooling if the concurrent operation of free
cooling and first stage mechanical cooling does not satisfy
the space thermostat's second stage cooling demand after
a time delay period. See Menu ADVANCED SETUP,
parameter STG3 DLY; default is 2.0 hours delay after
Y1- - O stage is energized. Combined Stage 3 operation
(both mechanical cooling stages) will terminate when
demand Y2 is satisfied.
Heating With EconoMi$er X
When the space temperature calls for heat (W1 closes),
CTB terminal W1 is energized. The supply fan will start
and run in High Speed. The W1 signal will connect
toW7220 input AUX2I; the outside air damper will move
to MIN POS H. Unit heating sequence will follow base
unit control sequences.
Demand Control Ventilation
If a space or return air CO
Economize X control, a Demand Control Ventilation
strategy will operate automatically.
When the space CO
(default 1100 ppm), the minimum ventilation position for
the outside air damper will be reset to lower settings
suited for offsetting CO
including people. The settings will vary according to
supply fan speed. When the supply fan speed is Low, the
DCV minimum ventilation point is VENTMIN L. When
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Temperature
Lockout
1
/
minutes.
2
sensor is connected to the
2
level is below setpoint DCV SET
2
loads from space sources not
2
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the supply fan speed is High, the DCV minimum
ventilation point is VENTMAX H.
As the CO
level in the space increases above the setpoint
2
DCV SET (default 1100 ppm), the DCV ventilation
position of the outside air damper will be increased
proportionally, until the Maximum Ventilation setting is
reached. The settings will vary according to supply fan
speed. When the supply fan speed is Low, the DCV
maximum ventilation point is VENTMAX L. When the
supply fan speed is High, the DCV maximum ventilation
point is VENTMAX H.
DCV operation will float between its VENTMIN and
VENTMAX settings, never exceeding the VENTMAX
—
The
limit as the space CO
in people occupancy levels.
During concurrent demand for DCV and free cooling, the
outdoor- - damper will follow the higher demand condition
from the DCV mode or from the free- - cooling mode.
SETUP AND CONFIGURATION
Before being placed into service, the W7220 Economizer
module must be setup and configured for the installed
system according to project control specifications.
Inspect all wiring connections at the Economizer module's
terminals, and verify compliance with the installation
wiring diagrams.
Initial Menu Display
On initial start up, Honeywell displays on the first line and
Economizer W7220 on the second line. After a brief
pause, the revision of the software appears on the first line
and the second line will be blank.
Time- -out and Screensaver
When no buttons have been pressed for 10 minutes, the
LCD displays a screen saver, which cycles through the
Status items. Each Status items displays in turn and cycles
to the next item after 5 seconds.
IMPORTANT: During setup, the Economizer module is
live at all times.
Setup and configuration involves stepping through three
menus and enabling required functions and re- - selecting
setpoints to meet project requirements. The menus used
are SYSTEM SETUP, ADV SETUP and SETPOINTS.
Obtain a copy of the project control specifications before
starting setup and configuration process.
NOTE: W7220 will be in the "set up" mode for the first
60 minutes after powered. If a sensor for OA air or S- - bus
device (sensor, actuator) is disconnected during the set up
mode, the W7220 will not alarm that failure. The SAT
sensor is a system "critical" sensor, if the SAT sensor is
removed during the set up mode, the W7220 will alarm.
After 60 minutes the W7220 controller will change to
operation mode and all components removed or failed will
alarm in the operation mode.
18
level varies according to changes
2
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