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Manual 2100-447
Page 7
FIGURE 5
ECONOMIZER OPERATION
F. Readjust temperature on the thermostat to
engage the second stage of cooling (Y2).
The damper motor should return to previously
set minimum position. Compressor motor
should start.
G. Switch thermostat to OFF fan and OFF heat/
cool positions to de-energize unit.
Economizer damper should return to full
closed (100 percent return air) position.
Checkout is complete.
16. Replace control access panel and mist eliminator.
17. Remove blank off plate or barometric fresh air
damper if installed on the service access panel.
Plug the four (4) holes used to mount the BOP or
BFAD with the plastic plugs supplied with the
economizer.
18. Replace service access panel.
19. Economizer is now ready for operation.
ECONOMIZER – WA, WL & WH SERIES
ECONOMIZER SEQUENCE OF OPERATION
Condition A – Cool Outdoors
First stage cooling closes and powers the economizer
dampers to economizer mode and the indoor blower
starts. Mixed Air Sensor senses a mixture of return air
and outdoor air and modulates the dampers
accordingly. Compressor operation is inhibited.
(See Figure 5.)
If second stage closes on the thermostat, the dampers
return to the closed or minimum position setting and
the compressor starts for mechanical cooling.
MIS-347
FEATURES
•
One piece construction – easy to install
with no mechanical linkage adjustment
required.
• Exhaust air damper – built in with
positive closed position. Provides
exhaust air capability to prevent
pressurization of tight buildings.
• Actuator motor – 24 volt, power open,
spring return with built in torque limiting
switch.
• Proportioning type control – for
maximum “Free Cooling” economy and
comfort with up to 100% outside air.
• Enthalpy control to monitor outdoor
temperature and humidity – adjustable.
• Minimum position potentiometer –
adjustable to control minimum damper
blade position.
• Mixed air sensor to monitor outdoor and
return air to automatically modulate
damper position.