Trane CXAO Installation Operation & Maintenance page 45

Refrigerant charge
Charge with unit stopped and in vacuum (refrigerant charge in the liquid phase)
Completely open the valve for it to close the service
connection. Connect the refrigerant cylinder to the service
connection without tightening the connection. Half close the
liquid shut off valve. If the circuit has been dehydrated and
vacuum, load liquid with the cylinder upside down. Weigh and
charge the appropriate amount. Open the valve completely.
Start the unit and let it run at full load for several minutes.
Check that the indicator is clear and without bubbles. Be
sure that the transparency condition without bubbles is due
to the liquid and not to the vapor. For correct unit operation
overheating must be at 4 to 7 °C and subcooling at 4 - 8 °C.
Too high values of overheating can be caused by a lack of
refrigerant, while high values of subcooling may indicate
excess charge.
After changing the charge, you should check that the unit
works within the declared values: in full load operation, by
measuring the temperature of the intake pipe downstream
of the bulb of the thermostatic valve; read the equilibrium
pressure on the evaporator on the low pressure gauge and
the corresponding saturation temperature.
Overheating is equal to the difference between the measured
temperatures. Measure then the temperature of the pipe of
liquid leaving the condenser and detect on the high-pressure
gauge the equilibrium pressure on the condenser and the
corresponding saturation temperature. Subcooling is the
difference between these temperatures. Charge is in the liquid
phase
Refrigerant charge addition with the unit running (refrigerant charge in the vapour phase)
Caution: Charge only vapor. Do not charge liquid because it
may damage the compressor.
Connect the cylinder to the service connection without
tightening the connection. Drain the connecting pipe and
tighten the connection. Charge each circuit until the indicator
shows liquid without bubbles. The unit now has an adequate
charge. Be careful not to overload the circuit. Loading more
than necessary leads to higher outlet pressure, higher power
consumption and possible damage to the compressor.
Charge is in the vapor phase
RF-SVX003A-GB
Refrigerant replacement procedure
spia liquido
presa alta pressione
presa bassa pressione
manometro
alta pressione
manometro
bassa pressione
gruppo manometro
spia liquido
presa alta pressione
presa bassa pressione
manometro
alta pressione
manometro
bassa pressione
gruppo manometro
bilancia
bilancia
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