22
Tubing
• Braze the tubing between the outdoor unit and indoor
coil. Flow dry nitrogen into a pressure port and
through the tubing while brazing, but do not allow
pressure inside tubing which can result in leaks.
Once the system is full of nitrogen, the nitrogen
regulator should be turned off to avoid pressuring the
system.
• After brazing, use an appropriate heatsink material
to cool the joint.
• Reinstall the Schrader cores into both pressure
ports.
• Do not allow the vapor line and liquid line to
be in contact with each other. This causes an
undesirable heat transfer resulting in capacity loss
and increased power consumption.
Leak Testing
Indoor coils have only a holding charge of dry
nitrogen. Keep all tube ends sealed until
connections are to be made.
WARNING:
Do not use oxygen
to purge lines or pressurize system for leak test.
Oxygen reacts violently with oil, which can cause
an explosion resulting in severe personal injury or
death.
• Pressurize line set and coil through service fittings
with dry nitrogen to 150 PSIG maximum. Close
nitrogen tank valve, let system sit for at least
15 minutes, and check to see if the pressure has
dropped. If the pressure has dropped, check for
leaks at the line set braze joints with soap bubbles
and repair leak as necessary. Repeat pressure test.
If line set and coil hold pressure, proceed with line
set and coil evacuation (see page 21).
• The vapor line must be insulated for its entire
length to prevent dripping (sweating) and prevent
performance losses. Closed-cell foam insulation
such as Armaflex and Rubatex
®
are satisfactory
insulations for this purpose. Use 1/2" [12.7 mm]
minimum insulation thickness. Additional insulation
may be required for long runs.
ST-A1226-07-00
ST-A1226-06-00
INSTALLATION
Interconnecting Tubing (cont.)
