Installation, Operation and Maintenance Manual
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of creating flash gas at the top of the riser because of the increased pressure drop. This can cause stress
on the TXV and evaporator coil and shorten compressor life span. The system will also lose capacity and
increase operating cost.
Split Air-Cooled Unit Piping
Air-cooled unit piping is crimped and brazed closed from the factory and contains a nitrogen holding charge.
Each installation requires field-supplied refrigerant piping to a condenser.
Refer to the attached line sizing chart in section 3.3 for a guideline for sizing refrigerant lines. The ultimate
responsibility for line sizing selection is that of the installing contractor or the project engineer. Data Aire does
not assume this responsibility. The chart covers distances up to 200 equivalent feet. For installations greater
than this distance, consult ASHRAE or similar references.
Standard piping practices must be used to ensure proper oil return and efficient operation. The
interconnecting lines to the remote air-cooled condenser or condensing unit must be installed by a qualified
refrigeration mechanic.
Do not vent the nitrogen until all refrigerant 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. 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 flowing 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.
Be sure to open the other end of the refrigerant line to allow the nitrogen to bleed off and not pressurize the
piping. Pre-vailing good refrigeration practices should be employed for piping support, leak testing,
dehydration and charging the refrigerant circuits. During the installation, the lines should be capped off and
filled with dry nitrogen at the end of each day’s work or until the system is completed and sealed.
3.2.1
Discharge Lines
Discharge lines, also called hot gas lines, should be trapped at the top (inverted) and bottom as well as every 15 to
20 feet of vertical rise. Discharge check valves (field provided) are required on all installations, especially those
where there are long pipe runs or cold climates. For air cooled units built after 3/14/2017, the discharge check
valves are already included internal to the evaporator section and do not need to be installed in the external pipe
runs to the unit. For units built before this date, the check valves must be field supplied and installed externally to
the evaporator section. If there is doubt as to whether the check valve is already included with the unit, look for the
check valve on the hot gas line near to point where this line exits the unit (see example picture below). The
externally installed check valve should be placed no less than six (6) to ten (10) feet (1.8 to 3.1 m) from the
compressor.