Installation, Operation and Maintenance Manual
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14
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100
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Do not leave dehydrated piping or components open to atmosphere any longer than is required. Keep
piping clean and dry, especially on units with R-410A refrigerant.
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Piping should be designed with adequate three-dimensional flexibility. It should not be in contact with
the surrounding structure unless a proper tubing mount has been installed. This protection proves
necessary to avoid excess vibration, which can ultimately result in connection or tube failure due to
fatigue or wear from abrasion. Aside from tubing and connection damage, excess vibration may be
transmitted to the surrounding structure and generate an unacceptable noise level within the structure
as well. Units should be installed with proper piping devices (supporting saddles, etc.). Care must be
taken in isolating the refrigerant tubing from the building. Vibration isolation support is recommended.
Avoid piping runs through noise-sensitive areas, such as office walls and conference rooms.
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Standard refrigeration practices should be followed for leak testing, evacuation and refrigerant charging
of the refrigerant circuit.
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Based on ASHRAE's Refrigeration Handbook, a properly designed and installed refrigerant piping system
should:
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Provide adequate refrigerant flow to the evaporators, using practical refrigerant line sizes that limit
pressure drop
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Avoid trapping excessive oil so that the compressor has enough oil to operate properly at all times
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Avoid liquid refrigerant slugging
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Be clean and dry
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The interconnecting lines require installation by a qualified refrigeration mechanic.
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Good refrigeration piping design requires that the refrigeration lines be pitched in the direction of flow
at approximately 1/2 inch (12.7 mm) per 10 feet (3.1 m) or 1 inch (25 mm) per 20 feet (6.1 m).
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ASHRAE Standard 15 and ASME Standard B31.5 should be used as guides for safe practice because they
are the basis of most municipal and state codes. However, some ordinances require heavier piping and
other features. The designer or engineer should know the specific requirements of the installation site.
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Ensure that the pipe surfaces to be brazed are clean and that all burrs have been removed from the ends
of the pipes. Ensure that all loose material has been cleaned from inside the pipe before brazing.
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Proper piping practices should be employed to ensure adequate oil return, even under minimum load
conditions with special consideration given to the size and proper slope of the tubing coming from the
evaporator. Tubing returns from the evaporator should be designed so as not to trap oil and to prevent
oil and refrigerant migration back to the compressor during off-cycles.
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Refer to the line size refrigerant piping chart for a guideline for sizing refrigerant lines. The ultimate
responsibility for line sizing is that of the installing contractor or project engineer. Data Aire does not
assume this responsibility.
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Refer to the ASHRAE Refrigeration Handbook for general, good-practice refrigeration piping.
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All piping below the raised floor must be located so that it does not restrict airflow. Plan the piping layout
under the raised floor, if applicable, to prevent the airflow from being blocked. When installing piping on
the subfloor, it is recommended that the pipes be mounted in a horizontal plane rather than stacked one
above the other. Whenever possible, the pipes should be run parallel to the airflow.
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When installing the condenser below the evaporator section the vertical rise between the condenser and
evaporator section should not exceed 15 feet. When liquid lift is higher than 15 feet, there is a possibility
