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Installing Outdoor Units Indoors
Single Zone Extended Piping Wall Mounted outdoor units are engineered to be mounted outdoors and include technology designed to mini-
mize 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.
• 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 will allow the Single Zone Extended Piping Wall Mounted
system designer to eliminate oversizing.
• The outdoor unit to compensate for loss of capacity at low ambient temperatures.
• Will also curtail the need to provide inefficient redundant zone heating devices such as wall-fin radiators and second-stage ancillary heating
devices.
Design Considerations Include:
• Enclosure types and elements such as louvers (see next page), rain hoods, dampers and controls, heating methods and sizing of heating
devices.
• Heating strategies.
• Duct design.
• Condensate handling.
General Guidelines
• Follow ASHRAE 62.1 design guidelines.
• Depending on the project / application, a roof over the outdoor units in combination with a wind break will be all that is necessary.
• Consider the potential for snow accumulation near louvers / roof openings. Outside air intakes and discharge ducts/louvers must be engi-
neered to clear anticipated snow accumulation levels by at least one (1) foot.
• In situations where operation is anticipated at temperatures lower than the product's minimum operating temperature, ancillary heat must
be provided to heat the outdoor unit coils to ensure continuous compressor operation and heating.
•
It will be necessary to use a field-fabricated air guide to prevent discharge air from short-cycling back to the coil inlet.
• Consider the direction of prevailing winds and opening placement. If possible, locate inlet openings upwind of discharge openings and other
exhaust outlets.
• When inlet and outlet openings are placed on the same wall, minimum distance between the two openings must 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 must be designed to avoid weather related long periods of water entrainment and the potential for microbial
growth.
PLACEMENT CONSIDERATIONS
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Installing Outdoor Units Indoors
REFRIGER ANT DESIGN | 51
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