40 | APPLICATION GUIDELINES
Single Zone W
all Mounted Extended Piping Engineering Manual
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BUILDING VENTILATION DESIGN GUIDE
Method 1: 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 con-
ditioned space through a separate register or grille. This approach requires a separate independent ventilation duct system not associated
with single zone systems.
Advantages
• May be used with single zone systems.
• The outdoor air unit may supply “neutral” air to the occupant space
even when the single zone system indoor unit fan changes speed
or cycles on and off. DDOAS controls do not have to be interlocked
with the single zone 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
centralized outdoor air unit and ceiling diffusers.
LG recommends using the DDOAS method in all installations.
Ceiling Diffuser
Outdoor Air Unit / ERV
Outdoor Air
Wall Mount Inverter
Intake Grill
Figure 6: Decoupled Dedicated Outdoor System Diagram
Methodology illustrations are for examples only and do not depict actual
indoor units for the specific outdoor unit pairing. These are generic illus
-
trations to show ventilation design only.
Building Ventilation Design Guide
ASHRAE 62.1 and local codes specify the minimum volume of outdoor air that must be provided to an occupied space. Outdoor air is re-
quired to minimize adverse health effects, and it provides acceptable indoor air quality for building occupants. The three methods of accom-
plishing this with single zone systems are summarized here.
Although we believe that these building ventilation methods have been portrayed accurately, none of the methods have been tested, verified, or
evaluated by LG Electronics, U.S.A., Inc., In all cases, the designer, installer, and contractor should understand if the suggested method is used, it
is used at their own risk. LG Electronics U.S.A., Inc., takes no responsibility and offers no warranty, expressed or implied, in law or in fact, including
but not limited to any implied warranty of merchantability or fitness for a particular purpose.
• For a complete copy of Standard 62.1-2010, refer to the American Standard of Heating and Air Conditioning Engineers (ASHRAE)
website at www.ashrae.org.
• For more information on how to properly size a ventilation air pretreatment system, refer to the article, “Selecting DOAS Equipment with
Reserve Capacity” by John Murphy, published in the ASHRAE Journal, April 2010.
