
System Engineering
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SYSTEM ENGINEERING
Due to our policy of continuous product innovation, some specifications may change without notification.
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Outdoor Air
Unit/ERV
Indoor Unit
Flange (O.D. 6")
Ventilation Kit
Front Panel
OA Wall
Louver
Damper
Roof Fan
Method 5: Coupled Dedicated Outdoor Air (CDOAS)
A separate, dedicated outdoor air system delivers air directly to a Multi V 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 filter-
ing, conditioning, and dehumidifying outdoor air to room neutral conditions.
BUILDING VENTILATION
Method 4: Unconditioned Outdoor Air (Non-Ducted, Fan Assisted Ventilation)
When approved by local codes, the fan assisted ventilation method uses exhaust fans to remove air from the building, and outdoor air is
drawn into occupied spaces through a wall louver or gravity roof intake hood. Supply fans can also be used to push the outdoor air into the
space and building positive pressure will vent the exhaust air through louvers or roof-mounted exhaust hoods. Outdoor air is neither cooled
nor heated before entering the building.
Note:
This may result in
loss of building pres-
surization control,
increasing in
fi
ltration
loads with adverse
effects.
Advantages:
Outdoor air may be manually controlled by the occupant or automatic
controls may be installed to open/close outdoor air dampers or to turn on/
off ventilation fans.
Useful for large open spaces like warehouses, garages, and workshops.
Outdoor air volume is a known quantity. Air loads may be easier to calcu-
late since fans will regulate the amount of outdoor air.
May be used with a full lineup of Multi V indoor units.
Disadvantages:
In some locations of the country,
it may be difficult to control
humidity levels while outdoor air
louvers/hoods are opened.
Thermal comfort levels may
be substandard when louvers/
hoods are opened.
Indoor units may have to be
oversized to account for the
added heating/cooling loads
when louvers/hoods are open.
Hot, cold, and/or humid areas
may be present if the outdoor air
is not evenly distributed to the
different spaces.
Note:
Outside air may
fl
ow
backward through the
return air-
fi
lter grille
when the indoor unit
fan speed is reduced
or stops when the
space load is satis-
fi
ed. This may result
in captured particu-
late on the
fi
lter me-
dia being blown back
into the conditioned
space.
Advantage:
Separate ceiling registers
or grilles for introduction
of the outside air to the
conditioned space may be
avoided.
Disadvantages:
Ducted, 1-way and 4-way cassette indoor units are the only models de-
signed for direct connection of an outside air duct.
The building occupant may not notice the outdoor air pretreatment system
has malfunctioned until the unconditioned outdoor air exceeds the indoor
unit mixed air limits of 59°F DB for heating and 76°F WB for cooling.
If the coil entering air condition limitation is exceeded, the indoor unit may
malfunction and prevent the indoor unit from operating.
If the outdoor air unit cooling or heating system fails, the malfunction may
be masked by the indoor unit ramping up operating parameters to compen-
sate for the failure.
Motorized dampers may be required to prevent outdoor air from entering
the indoor unit while the indoor unit has cycled off.
An LG Dry Contact adapter is necessary to interlock the motorized damper
with the indoor unit fan 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 ac-
curate conditioned space temperature reading.
Indoor Unit
Flange (O.D. 6")
Ventilation Kit
Front Panel
Содержание Multi V mini
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