BUILDING VENTILATION DESIGN GUIDE
Method 4: Coupled Dedicated Outdoor Air (CDOA)
A separate, dedicated outdoor air system delivers air directly to a Multi F indoor unit or to the return air duct system. After mixing with the
return air stream, ventilation air passes through the indoor unit and into the conditioned space. The pretreatment system is capable of
filtering, conditioning, and dehumidifying outdoor air to room neutral conditions.
Advantages
• Indoor unit capacity may not need to be
increased because of outdoor air.
• Fan and filter system is centralized to the
main outdoor air unit.
Disadvantages
• Ducted and four-way cassette indoor units are the only models designed for direct
connection of an outside air duct.
• Ceiling space is required for ductwork.
• Failure of outdoor air may impact indoor unit operation.
• In lieu of using the factory mounted return-air thermistor, a remote wall temperature
sensor or zone controller may be required to provide an accurate conditioned space
temperature reading.
Outside air may flow backward through the return air-filter grille when the indoor unit fan speed is reduced or stops when the space load is
satisfied. This may result in captured particulate on the filter media being blown back into the conditioned space.
Outdoor
Air Unit
Figure 251:
Coupled Dedicated Outdoor Air (CDOA).
Due to our policy of continuous product innovation, some specifications may change without notification.
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LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. “LG” is a registered trademark of LG Corp.
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Application Guidelines
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