LG MULTI F Series Engineering Manual page 350

BUILDING VENTILATION DESIGN GUIDE
Method 3: Unconditioned Outdoor Air Ducted to Indoor Units
Untreated outdoor air is channeled through a duct system that is piped to the return air duct on Multi F ducted indoor units or to the frame of
Multi F four-way cassettes.
Outside air may flow backward through the return air-filter grille when the indoor unit fan speed slows or stops in response to changes in the
space load. This may result in captured particulate on the filter media being blown back into the conditioned space.
Advantages
• May require less ductwork if indoor units are
placed near outdoor walls or a roof deck.
• Controls must be interlocked to shut off the
outdoor air supply fan when the space is
unoccupied.
• Third-party demand-control ventilation
controls may be installed to regulate outdoor
intake based on the CO levels of the
2
occupied space.
Figure 41: Unconditioned Outdoor Air Ducted to Indoor Units.
Damper
OA Wall Cap
350 | APPLICATION GUIDELINES
Disadvantages
• Fan(s) will be required to push outdoor air to the indoor unit to overcome the additional
static pressure.
• Filter required to be added to the outdoor air duct.
• Ducted and four-way cassette models are the only indoor units that accept the connection
of an outdoor air duct to the unit case.
• In most cases, in lieu of using the factory mounted return-air thermistor on indoor units, a
remote wall temperature sensor or zone controller will be needed to provide an accurate
reading of the conditioned area temperature.
• Unconditioned outdoor air may affect indoor unit performance, which may necessitate
oversizing the indoor unit.
Inline Fan
with Filter
Due to our policy of continuous product innovation, some specifications may change without notification.
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