Fujitsu FO20R Series Installation Instructions Manual page 20

4.0 INSTALLATION
4.5.3 Tubing Connections
Indoor coils have only a holding charge of
dry nitrogen. Keep all tube ends sealed until
connections are to be made.
• Use type "L" copper refrigeration tubing. Braze
the connections with the following alloys:
– Copper to copper, 5% silver minimum
– Copper to steel or brass, 15% silver minimum
• Be certain both refrigerant shutoff valves at the
outdoor unit are closed.
• Remove the caps and Schrader cores from the
pressure ports to protect seals from heat damage.
Both the Schrader valves and the service valves
have seals that may be damaged by excessive heat.
• Clean the inside of the fittings and outside of the
tubing with a clean, dry cloth before soldering. Clean
out debris, chips, dirt, etc., that enters tubing or
service valve connections.
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• Wrap valves with a wet rag or thermal barrier
compound before applying heat.
• 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 bare 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.