NOTE: All indoor and outdoor suction-line piping must have 1/2 in. minimum of insulation. All outdoor
insulation must be UV and ozone resistant.
NOTE: Proper safety equipment and proper refrigeration tools are required when working with R-410A
refrigerant. Check unit serial tag for correct refrigerant type before topping-off or recharging a system.
NOTE: Refrigerant R-410A uses a POE (polyolester) lubricant. The refrigerant must be introduced and
charged from the cylinder only as a liquid.
NOTE: When installing field piping, you must take care to protect all refrigerant lines from the
atmosphere especially when using refrigerants with POE oils. Do not allow the piping to stand open to
air for more than 15minutes. Units designed for R-410A have a compressor that contains POEoil,
which quickly absorbs water from the air. The longer that the refrigerant piping is left open to air, the
harder it will be to fully evacuate the system. If left open too long, the POE oil may require replacement
to achieve the required vacuum level.
• Refer to Refrigerant-line Sizes and Equivalent Lengths on the next page,for recommended
refrigerant piping sizes based on equivalent pipe lengths.
• Refer to Refrigerant Charge Requirements on the next page, for the refrigerant-charge
requirements of the system.
4.1.2 Piping when Condensing Unit is Above or Below Evaporator
Refer to Table 4.3 below for the maximum vertical rise/fall between condensing unit and evaporator.
When installing remote condensing units above the evaporator, trap the suction gas line at the
evaporator as shown in Figure 4.1 on the next page. This trap will retain refrigerant oil during the "Off"
cycle. When the unit starts, oil in the trap is carried up the vertical riser and returns to the compressor.
When installing remote condensing units below the evaporator, trap the suction gas line with an inverted
trap the height of the evaporator as shown in the following figure. This prevents refrigerant migration to
the compressor during "Off" cycles.
Maximum Equivalent Pipe Length, ft (m)
Maximum
Condensing-unit Level
Above Evaporator, ft (m)
Maximum
Condensing-unit Level
Below Evaporator, ft (m)
150 (45) 50 (15) 15 (4.6)
Table 4.3 Pipe length and condensing unit elevation relative to
evaporator
4 Piping and Refrigerant Requirements 13
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