39
REFRIGERANT PIPING FOR THE
CL SERIES
General:
Piping from the condensing unit to the air handler
is the responsibility of the installing contractor.
Use only clean type “ACR” copper tubing that has
been joined with high temperature brazing alloy.
The pipe or line sizes must be selected to meet the
actual installation conditions and NOT simply
based on the connection sizes at the condensing
unit or air handler.
All AAON CL condensing units have factory
furnished liquid and suction line shutoff valves.
These must remain closed until the system is
ready for start-up after installation.
Upon completion of piping connection, the
interconnecting piping and air handler MUST BE
evacuated to 500 microns or less; leak checked
and charged with refrigerant.
Care must be taken not to cross the circuits on
multiple circuit systems.
Determining Refrigerant Line size:
The piping between the condenser and low side
must assure:
1.
Minimum pressure drop,
and
2.
Continuous oil return,
and
3.
Prevention of liquid refrigerant slugging,
or carryover
Minimizing the refrigerant line size is favorable
from
an
economic
perspective,
reducing
installation costs, and reducing the potential for
leakage. However, as pipe diameters narrow,
pressure-reducing frictional forces increase.
Excessive suction line pressure drop causes loss
of compressor capacity and increased power
usage resulting in reduced system efficiency.
Excessive pressure drops in the liquid line can
cause the liquid refrigerant to flash, resulting in
faulty expansion valve operation and improper
system performance. In order to operate
efficiently and cost effectively, while avoiding
malfunction, refrigeration systems must be
designed to minimize both cost and pressure loss.
The pipe sizes must be selected to meet the
actual installation conditions, and not simply
based on the connection sizes at the evaporator
and/or condensing unit.
Equivalent Line Length:
All line lengths discussed in this manual, unless
specifically stated otherwise, are Equivalent Line
Lengths. The frictional pressure drop through
valves, fittings, and accessories is determined by
establishing the equivalent length of straight pipe
of the same diameter.
Always use equivalent line
lengths when calculating pressure drop
.
Special piping provisions must be taken when
lines are run up vertical risers or in excessively
long line runs.
Do not run underground
refrigerant lines.
REFRIGERANT PIPING
This section is for information only and is
not intended to provide all details required
by the designer or installer of the
refrigerant piping between the condenser
or condensing unit and the air handling
unit. AAON, Inc. is not responsible for
interconnecting refrigerant piping. Consult
ASHRAE Handbook
– Refrigeration and
ASME Standards.
CAUTION
