4
Refrigerant Line Connections
IMPORTANT
To avoid overheating the service valve, TXV valve, or filter
drier while brazing, wrap the component with a wet rag, or
use a thermal heat trap compound. Be sure to follow the
manufacturer’s instruction when using the heat trap
compound. Note: Remove Schrader valves from service valves
before brazing tubes to the valves. Use a brazing alloy of 2%
minimum silver content. Do not use flux.
Torch heat required to braze tubes of various sizes is
proportional to the size of the tube. Tubes of smaller size
require less heat to bring the tube to brazing temperature
before adding brazing alloy. Applying too much heat to any
tube can melt the tube. Service personnel must use the
appropriate heat level for the size of the tube being brazed.
Note: The use of a heat shield when brazing is recommended
to avoid burning the serial plate or the finish on the unit.
1. The ends of the refrigerant lines must be cut square, de-
burred, cleaned, and be round and free from nicks or dents.
Any other condition increases the chance of a refrigerant
leak.
2. “Sweep” the refrigerant line with nitrogen or inert gas dur-
ing brazing to prevent the formation of copper-oxide inside
the refrigerant lines. The POE oils used in R-410A applica-
tions will clean any copper-oxide present from the inside of
the refrigerant lines and spread it throughout the system.
This may cause a blockage or failure of the metering device.
3. After brazing, quench the joints with water or a wet cloth to
prevent overheating of the service valve.
4. Ensure the filter drier paint finish is intact after brazing. If
the paint of the steel filter drier has been burned or chipped,
repaint or treat with a rust preventative. This is especially
important on suction line filter driers which are continually
wet when the unit is operating.
NOTE: Be careful not to kink or dent refrigerant lines. Kinked or
dented lines will cause poor performance or compressor damage.
Do NOT make final refrigerant line connection until plugs are
removed from refrigerant tubing.
NOTE: Before brazing, verify indoor piston size by checking the
piston kit chart packaged with indoor unit.
Leak Testing (Nitrogen or Nitrogen-Traced)
To avoid the risk of fire or explosion, never use oxygen, high
pressure air or flammable gases for leak testing of a refrigeration
system.
Pressure test the system using dry nitrogen and soapy water to
locate leaks. If you wish to use a leak detector, charge the system
to 10 psi using the appropriate refrigerant then use nitrogen to
finish charging the system to working pressure then apply the
detector to suspect areas. If leaks are found, repair them. After
repair, repeat the pressure test. If no leaks exist, proceed to sys-
tem evacuation.
System Evacuation
Condensing unit liquid and suction valves are closed to contain
the charge within the unit. The unit is shipped with the valve
stems closed and caps installed. Do not open valves until the
system is evacuated.
NOTE: Scroll compressors should never be used to evacuate or
pump down a heat pump or air conditioning system.
Prolonged operation at suction pressures less than 20 psig for
more than 5 seconds will result in overheating of the scrolls and
permanent damage to the scroll tips, drive bearings and internal
seal.
CAUTION
1. Connect the vacuum pump with 250 micron capability to the
service valves.
2. Evacuate the system to 250 microns or less using suction
and liquid service valves. Using both valves is necessary as
some compressors create a mechanical seal separating the
sides of the system.
3. Close pump valve and hold vacuum for 10 minutes. Typi-
cally pressure will rise during this period.
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