Refrigerant Piping - Trane TWA Series Installation & Operation Manual

Refrigerant Piping

Structural Preparation
Holes must be made in the structure to run refrigerant lines.
For the majority of ground-level installations, the holes can be
made in the header that rests on top of the foundation.
Alternatively, these holes may also be made in the foundation
itself. On roof-mounted units, refrigerant lines should enter the
building as close to the unit as possible; preferably within three
to four inches of the refrigerant connection on the unit, plus a
six-inch (long radius) 90 degree ell entering the building. (See
Figure 4)
Refrigerant Piping Guidelines
A. Maximum recommended line lengths: (per circuit)
Maximum linear length ....................................... 80 Ft.
(w/o accumulator)
Maximum suction line lift ................................... 60 Ft.
Maximum liquid line lift ....................................... 60 Ft.
B. Maximum allowable pressure drops (R-22):
Suction line .......................................................... 6 psi
Liquid line (without subcooler) .......................... 35 psi
Route refrigerant piping for minimum linear length, minimum
number of bends and fittings (no reducers) and
minimum amount of line exposed to outdoor ambients.
C. Recommended line sizes:
Suction line - 1 3/8 inch sealed type L refrigerant tubing.
Liquid line - 1/2 inch sealed type L refrigerant tubing.
Note: Insulate all refrigerant piping and connections.
Refrigerant Piping Procedures (Outdoor Units)
Each TWA unit ships with a holding charge of dry nitrogen The
nitrogen should be removed and the entire system evacuated
(at the proper time) to avoid possible contamination.
1. Remove the compressor service access panel.
2. Locate the liquid and suction line service valves. Check
that the piping connection stubs on the valves (Figure 5)
line up properly with the holes in the unit cabinet.
Figure 5
TWA-SVX01A-EN
Installation
3. Remove the refrigerant connection seal caps and open the
service valve slowly to release the nitrogen from the unit.
CAUTION: Do not remove the seal caps from refrigerant
connections until prepared to braze refrigerant lines to the
connections. Excessive exposure to atmosphere may
allow moisture or dirt to contaminate the system,
damaging valve seals and causing ice formation in
system components.
4. Cut, fit and braze tubing, starting at the outdoor unit and
work toward the indoor unit.
Note: Use long radius ells for all 90 degree bends.
All brazing should be done using a 2 to 8 psig dry nitrogen
purge flowing through the pipe being brazed (Figure 5 ).
CAUTION: Install a regulating valve between the nitrogen
source and the gauge manifold (Figure 5). Unregulated
pressure can damage system components.
CAUTION: Wet-wrap all valves and protect painted
surfaces from excessive heat. Heat can damage system
components and the unit finish.
5. Shut off nitrogen supply.
6. Shut off the manifold valve for the line that is connected to
the suction line service valve. Disconnect the line from the
gauge port on the valve.
Figure 6
Refrigerant Piping Procedure (Indoor Unit)
Once liquid and suction lines are complete to the refrigerant
connections on the indoor unit, puncture the seal caps on the
indoor unit connection stubs to release the dry nitrogen
charge.
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