Manual

BUILDING VENTILATION DESIGN GUIDE

Method 5: Decoupled Dedicated Outdoor Air System (DDOAS)

Provide a separate, dedicated outdoor-air system designed to filter, condition, and dehumidify ventilation air and deliver it directly to the

conditioned space through a separate register or grille. This approach requires a separate independent ventilation duct system not

associated with the Multi F system.

Advantages

• May be used with the full lineup of Multi F indoor units.

• The outdoor air unit may supply “neutral” air to the occupant space

even when the Multi F indoor unit fan changes speed or cycles on

and off. DDOAS controls do not have to be interlocked with the

Multi V F system.

• In lieu of installing localized smaller outside air treatment

equipment throughout the building, this method centralizes the

ventilation air source making service and filter changes easier and

less disruptive for the building occupants.

• Third-party demand control ventilation controls are more readily

accommodated.

Disadvantages

• Ceiling space is required to accommodate ductwork between the

outdoor air unit and ceiling diffusers.

LG recommends using the DDOAS method in all installations.

Outdoor

Air Unit

Indoor Unit s

Ceiling Diffuser

Indoor Unit

Figure 44: Decoupled Dedicated Outdoor Air System (DDOAS).

Methodology illustrations are for examples only and do not depict actual

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trations to show ventilation design only.

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56 | APPLICATION GUIDELINES

Multi F and Multi F MAX Indoor Unit Engineering Manual

MULTI

MAX

MULTI