Multi F Outdoor Unit Engineering Manual

Table Of Contents

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 ow backward through the return air-lter grille when the indoor unit fan speed is reduced or stops when the space load is

satised. This may result in captured particulate on the lter media being blown back into the conditioned space.

Outdoor

Air Unit

Figure 42: Coupled Dedicated Outdoor Air (CDOA).

Due to our policy of continuous product innovation, some specications may change without notication.

ApplicAtion Guidelines | 189

Application Guidelines

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