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Systems should be designed to avoid HGBP whenever
possible. For more information about HGBP , refer to the
Engineers Newsletter, "Hot Gas Bypass – Blessing or a
Curse?" (ADM-APN007-EN).
Remodel, Retrofit, or
Replacement
Inevitably, older condensing units and evaporator
systems will need to be replaced or retrofitted. Due to the
phase-out of many of these older refrigerants, the major
components for those older units or systems may no
longer be available. The only option will be to convert the
system to R-410A, POE oil, and R-410A components.
When upgrading an existing refrigerant split system due
to remodel, retrofit, or replacement, the entire system
must be reviewed for compatibility with R-410A and POE
oil. Each and every part of the split HVAC system MUST be
compatible with the properties of R-410A refrigerant and
POE oil. In addition, ensure the existing electrical service
is adequate for the product being installed.
WARNING
R-410A Refrigerant under Higher Pressure
than R-22!
Failure to use proper equipment or components as
described below, could result in equipment failing and
possibly exploding, which could result in death, serious
injury, or equipment damage. The units described in
this manual use R-410A refrigerant which operates at
higher pressures than R-22. Use ONLY R-410A rated
service equipment or components with these units. For
specific handling concerns with R-410A, please contact
your local Trane representative.
Every part of an existing split system needs to be analyzed
to determine if it can be reused in an R-410A and POE oil
system:
•
R-22 condensing units will not work with R-410A; they
must be replaced.
•
Most older evaporator coils were not pressure- and
cycle-rated for R-410A pressures. If they weren't, they
will need to be replaced. If they were properly
pressure-rated for R-410A, existing coils must be
modeled to determine if they will meet capacity
requirements, are properly circuited, have correctly
sized distributor tubes, and employ acceptable
distributors and orifices.
CLCH-SVX009A-EN
Coil Piping and Connections
•
The required R-410A line sizes may be different than
the existing line sizes. The lines need to be re-sized and
compared to existing lines for reusability.
•
Suction lines 2-5/8 OD and smaller of type L copper are
suitable for use with R-410A. Suction lines 3-1/8 OD
must use type K or thicker wall.
•
Discharge lines, liquid lines, heat pump vapor lines,
and hot gas bypass lines 1-3/8 OD and smaller of type
L copper are suitable for use with R-410A. These same
lines sized at 1-5/8 OD or 2-1/8 OD must use type K or
thicker wall.
•
Expansion valves need to be reselected. Expansion
valves are refrigerant specific.
•
Any gasket or o-ring should be replaced. Shrinkage of
the original seal may occur after an HFC conversion,
potentially causing a refrigerant leak. Components
commonly affected are Schraeder cores, solenoid
valves, ball valves, and flange seals. But all external
seals in contact with refrigerant should be viewed as
potential leak sources after a retrofit.
•
All other valves, filters, valve packing, pressure
controls, and refrigeration accessories must be
researched through their manufacturer for
compatibility with the pressures of an R-410A system,
and for their compatibility with the newer POE oil.
•
For the best performance and operation, the original
mineral oil should be removed from the components
of the system that are not being replaced. Any
component of the system that is suspected of trapping
oil (piping, traps, and coil), should be dismantled,
drained, and reassembled. After all components have
been drained, the amount of residual mineral oil will
have a negligible effect on performance and reliability.
NOTICE:
Compressor Damage!
POE oil is hygroscopic – it absorbs water directly from
the air. This water is nearly impossible to remove from
the compressor oil and can cause compressor failures.
For this reason, the system should not be open for
longer than necessary, dry nitrogen should flow in the
system while brazing, and only new containers of oil
should be used for service and maintenance.
All Codes take precedence over anything written here.
37
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