15
The check valve will prevent ow from the condenser to the compressor during the “o”cycle.
The evaporator section ships with a nitrogen holding charge. Do not vent the evaporator until all re-
frigerant piping is in place, ready for connection to the evaporator and condenser. The discharge,
suction and liquid lines need to be refrigerant grade copper and in accordance with local code. All
refrigeration piping should be installed with high temperature brazed joints. When brazing, a supply
of nitrogen gas needs to be fed through the refrigerant lines. Be sure to open the other end of the
refrigerant line to allow the nitrogen to bleed o and not pressurize the piping. Prevailing good refrig-
eration practices should be employed for piping support, leak testing, dehydration and charging the
refrigerant circuits. During the installation, the lines should be capped o and lled with dry nitrogen
at the end of each day’s work or until the system is completed and sealed.
Data Aire recommends a silver/phosphorus/copper alloy with 5 to 15% silver be used to braze the
refrigerant line sets to the indoor and outdoor units. Nitrogen needs to be owing through the lines to
eliminate carbon deposit build-up on the inside of the joints. Carbon could contaminate the refrigerant
and restrict the metering device.
Piping must be supported within 18” (457 mm) of the inlet and outlet connections external to the unit.
Internal to the unit, the inlet connection is located on the top header of all units. The discharge outlet
is located at the bottom of the header.
Discharge line pressure drop should not exceed 9 PSI (62 kPa) for R-410A. Recommended gas ve-
locity for proper oil return is 1,000 FPM (5.1 m/sec). Slope horizontal lines downward in the direction
of the refrigerant ow. The recommended slope is 1/2” (12 mm) for every ten (10) feet (3 m) of line
length. Discharge lines do not require insulation but due to the high temperatures of the refrigerant
inside the line, the pipes may be insulated to protect against burns to individuals near or around the
lines.
2.7.3 Liquid Lines
Liquid line size is determined by pressure drop and velocity. The liquid line pressure drop should not
exceed 9 PSI (62 kPa) for R-410A. The recommended liquid velocity should be between 200 and 300
FPM (1 to 1.5 m/sec). To avoid excessive liquid line pressure drop, the air cooled condenser should
be located above or at the same level as the evaporator. Condenser installations more than 15 feet
below the evaporator are not recommended. Insulation of liquid lines is not required but can be useful
in preventing excessive sub-cooling or ashing on long exposed pipe runs.
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