5
Burying Refrigerant Lines
If burying refrigerant lines cannot be avoided, use the following
checklist.
1. Insulate liquid and suction lines separately.
2. Enclose all underground portions of the refrigerant lines in
waterproof material (conduit or pipe) sealing the ends where
tubing enters/exits the enclosure.
3. If the lines must pass under or through a concrete slab,
ensure lines are adequately protected and sealed.
Refrigerant Line Connections
IMPORTANT: To avoid overheating the service valve, TXV valve
or filter dryer 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, deburred,
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 during
brazing to prevent the formation of copper-oxide inside the
refrigerant lines. The POE oils used in R-410A applications
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 dryer paint finish is intact after brazing. If the
paint of the steel filter dryer has been burned or chipped,
repaint or treat with a rust preventive. This is especially
important on suction line filter dryers which are continually
wet when the unit is operating.
NOTES:
■
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.
■
Before brazing, verify indoor piston size by checking the
piston kit chart packaged with indoor unit.
Leak Testing—Nitrogen or Nitrogen-Traced
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, and then use nitrogen
to finish charging the system to working pressure. Apply the
detector to suspect areas. If leaks are found, repair them. After
repair, repeat the pressure test. If no leaks exist, proceed to
system 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.
NOTE: 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.
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. Typically
pressure will rise during this period.
Goodman 17
WARNING
To avoid the risk of fire or explosion, never use oxygen,
high pressure air or flammable gases for leak testing of a
refrigeration system.
Goodman 18
WARNING
To avoid possible explosion, the line from the nitrogen
cylinder must include a pressure regulator and a pressure
relief valve. The pressure relief valve must be set to open at
no more than 150 psig.
Goodman 19
REFRIGERANT UNDER PRESSURE!
Failure to follow proper procedures may cause property
damage, personal injury or death.
WARNING
Goodman 20
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