Installing Outdoor Units Indoors
LG Multi V outdoor units are engineered to be mounted outdoors and include technology designed to minimize the negative effects of winter
weather's freezing rain, sleet, and snow. Some building projects, however, necessitate placing the HVAC outdoor units indoors:
• Lack of ground space.
• Lack of an appropriate outdoor location that meets system design requirements.
• When mounting on the roof is not an option due to a lack of roof space.
• Roof warranty will be voided if mechanical equipment is placed on the membrane.
• On retrofit projects, a former chiller/boiler/air handler equipment room, mechanical area, or penthouse already exists.
• Where a project has vertical, self-contained VAV air handlers on each floor (in lieu of a centralized mechanical room).
• To curtail the potential need for redundant zone heating devices such as wall-fin radiators or duct heaters.
• In extremely cold environments where there is a significant amount of run-time at temperatures well below freezing outside the outdoor unit
ambient air temperature range published in this engineering manual.
Benefits of Installing Outdoor Units Indoors
• Shelters the outdoor unit from direct exposure to prevailing winds that decrease the heating capability of the outdoor unit.
• Protects equipment from freezing precipitation and/or potential ice build-up that could hinder unit operation.
• Maintains coil heat transfer efficiency by reducing the number of and shortening the cycle time for defrost operation.
• Easier maintenance and servicing during inclement weather.
• When mounted in a fully enclosed space, limiting the ambient air temperature may allow the Multi V system designer to eliminate oversizing
the outdoor unit to compensate for loss of capacity at low ambient temperatures.
• May also curtail the need to provide inefficient redundant zone heating devices such as wall-fin radiators and second-stage ancillary heat-
Design Considerations Include:
• Enclosure types and elements such as louvers, rain hoods, dampers and controls, heating methods and sizing of heating devices
• Heating strategies
• Duct design
• Condensate handling
• Follow ASHRAE 62.1 design guidelines.
• Depending on the project / application, a roof over the outdoor units in combination with a wind break may be all that is necessary.
• Consider the potential for snow accumulation near louvers/roof openings. Outside air intakes and discharge ducts/louvers should be engi-
neered to clear anticipated snow accumulation levels by at least one (1) foot.
• In situations where operation is anticipated at temperatures of -13°F and lower, ancillary heat should be provided to heat the outdoor unit
coils to assure continuous compressor operation and heating.
It may be necessary to use an air guide accessory to prevent discharge air from short-cycling back to the coil inlet.
• Another option is to field manufacture ductwork and mount on top of the unit to encompass the outdoor unit fan discharge and connect to
the exterior discharge grille on the building.
• Avoid using a single duct on multi-fan units to prevent short cycling. Provide a dedicated duct for each outdoor unit fan discharge.
• Consider the direction of prevailing winds and opening placement. If possible, locate inlet openings upwind of discharge openings and other
• When inlet and outlet openings are placed on the same wall, minimum distance between the two openings should be approximately three
(3) feet (minimum distance varies significantly with variations in outlet opening face velocity).
• If roof-mounted ventilation openings are used, strategically locate the inlet ventilation opening(s) upwind of the outlet opening(s).
• Discharge and supply ductwork should be designed to avoid weather related long periods of water entrainment and the potential for micro-