LG Multi V mini Engineering Manual page 47

Method 2: Unconditioned Outdoor Air (Non-Ducted, Natural Ventilation)
Natural ventilation devices, such as operable windows or louvers may be used to ventilate the building when local code permits. The open
area of a window or the free area of a louver must meet the minimum percentage of the net occupied floor area.
Note:
None
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 concealed indoor units or to the chassis of
1-way and 4-way cassettes.
Note:
Outside air may fl ow
backward through the
return air-fi lter grille
when the indoor unit fan
speed slows or stops in
response to changes in
the space load. This may
result in captured par-
ticulate on the fi lter media
being blown back into the
conditioned space.
OA Wall Cap
Damper
Inline Fan
Inline Fan
Advantages:
Occupants control the
volume of the ventila-
tion air manually.
Useful for historic build-
ings that have no ceil-
ing space available for
outdoor air ductwork.
May be used with the
full lineup of Multi V
indoor units.
Advantages:
May require less ductwork if
indoor units are placed near
outdoor walls or roof deck.
Controls must be interlocked to
shut off the outdoor air supply fan
when the space is unoccupied.
Third-party demand-control ven-
tilation controls may be installed
in order to regulate outdoor intake
based on the CO levels of the
2
occupied space.
Indoor Unit
Flange
(O.D. 6")
Ventilat
Kit
Due to our policy of continuous product innovation, some specifications may change without notification.
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BUILDING VENTILATION
Disadvantages:
In some locations, it may be difficult to control humidity levels when
windows are open.
Thermal comfort levels may be substandard when windows are open.
Indoor units may have to be oversized to account for the added heat-
ing and cooling loads when windows are open.
Provides outdoor air to perimeter spaces only. Additional mechanical
ventilation system may be required to satisfy requirements for interior
spaces.
Outdoor air loads may be difficult to calculate since the quantity of
outdoor air is not regulated.
May affect indoor unit proper operation when open.
Disadvantages:
Fan(s) will be required to push outdoor air to the indoor unit. Indoor
units are engineered for low sound levels and are not designed to
overcome the added static pressure caused by the outdoor air source
ductwork.
Ventilation air must be pre-filtered before mixing with the return air
stream. LG indoor cassette models are configured to introduce the
ventilation air downstream of the return air filter media.
Ducted, 1-way and 4-way cassette models are the only indoor units that
accept the connection of an outdoor air duct to the unit case.
Mixed air conditions must be between a minimum of 59°F DB while
operating in Heating mode and a maximum of 76°F WB while operating
in Cooling mode. Depending on the ventilation air volume requirement,
the location choices are limited where untreated outside air may be
introduced to the building using this method.
Larger indoor units may be required to satisfy for additional outdoor air.
Motorized dampers may be required to prevent outdoor air flow through
the indoor unit when the indoor unit is not operating.
An LG Dry Contact adapter may be necessary to interlock the motorized
damper with the indoor unit.
While operating in Heating mode, the untreated outdoor air may delay
the start of the indoor unit fan impacting building comfort.
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 for each indoor unit to provide an accurate reading of the
conditioned area temperature.
49
SYSTEM ENGINEERING
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