System Superheat; System Subcooling - Trane R Series Installation Operation & Maintenance

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Start-Up Procedures
subcooling is also low. If the operating pressures, sight glass, superheat
and subcooling readings indicate a refrigerant shortage, gas-charge refrig-
erant into each circuit, as required. With the unit running, add refrigerant
vapor by connecting the charging line to the suction service valve and
charging through the backseat port until operating conditions become
normal.
NOTE: If both suction and discharge pressures are low but subcooling is
normal, a problem other than refrigerant shortage exists. Do not add refrig-
erant, as this may result in overcharging the circuit.
NOTE: Use only refrigerants specified on the unit nameplate, to prevent
compressor damage and insure full system capacity.
• If operating conditions indicate a refrigerant overcharge, remove refriger-
ant at the liquid line service valve. Allow refrigerant to escape slowly, to
minimize oil loss. Do not discharge refrigerant into the atmosphere.

System Superheat

Normal suction superheat for each circuit is approximately 6 F (4 F for RTUA
units) at full operating load. Superheat temperature can be expected to be
moving around the 6 F (4 F for RTUA) setpoint when the chiller is pulling
down or the compressor slide valve is being modulated. Superheat can be
expected to settle out at approximately 6 F (4 F for RTUA units) when the
above items stabilize.

System Subcooling

Normal subcooling for each circuit ranges from 6 F to 8 F , depending on the
unit. If subcooling for either circuit does not approximate these figures, check
the superheat for the circuit and adjust, if required. If superheat is normal but
subcooling is not, contact a qualified service technician.
RLC-SVX07A-EN