IM 893-10 • ROOFPAK SINGLEZONE UNITS 34 www.DaikinApplied.com
MeChanICal InsTallaTIon
Refrigerant Charge
Each unit is designed for use with R-410A.The total charge per
circuit is the sum of the following four values:
• Condenser section charge, see Table 11 on page 32.
• Evaporator coil charge, see Table 11.
• Charge for length of unit piping to the evaporator coil, see
Table 11.
• Charge for length of interconnecting piping between the
RCS and RFS units, installed by eld, see Table 12. The
exact charge for a one piece RPS/RDT is on the unit
nameplate.
Field Charging Procedure
Under normal (summertime) operating conditions, the
superheat at the compressor should be between 8ºF and 14ºF
and subcooling measured at the condenser outlet should be
15ºF (nominal).
With all compressors operating at full capacity, a 25ºF-35ºF
temperature difference should exist between the entering
condenser air and the temperature corresponding to the
compressor saturated discharge pressure.
For VFD compressor units, set the VFD compressor capacity
to 100% before measuring subcooling.
The recommended method for eld charging would be to
recover, evacuate and re-charge the system to the value on
the unit nameplate. If this method is not practical or verication
of charge is the purpose, then unit charge can best evaluated
by the amount of subcooling.
Follow Table 15 below for acceptable subcooling levels. To
calculate subcooling: take the difference between the liquid
temperature leaving the condenser and the temperature
corresponding to the compressor saturated discharge
pressure. It is important not to use the saturation pressure
at the condenser outlet as this will lead to an overcharged
state. When charging at ambients below 75ºF it is strongly
recommended to recover, evacuate and re-charge the unit to
the value on the unit nameplate.
Table 15: Typical Subcooling Operating Values
Outdoor Ambient Subcooling Range (see notes)
75–85ºF 5–10ºF
85–95ºF 10–15ºF
95–105ºF 15–20ºF
1. All compressors in circuit operating at full capacity
2. All condenser fans operating
3. Speedtrol condenser fan motor(s) operating at 100% (if option present)
4. Hot Gas Bypass not operating
5. MHGRH and liquid subcooling should not be operating
These units contain a microchannel condenser and the internal
volume of the refrigeration system is less than that compared
to a typical n-tube condenser. Unit refrigerant charge can be
as much as 40% less with microchannel and is much more
sensitive to charge levels. Caution should be exercised not to
overcharge the unit.
Refrigeration Service Valves
Units are shipped with a liquid line charging valve in each
circuit. RDT, RPS and RCS units have the following:
RDT, RPS and RCS Units—One liquid charging valve is
provided per refrigeration circuit, located at end of condensing
section opposite condenser control box.
Optional—One discharge valve and one suction valve is
provided for each refrigerant circuit, located in the condenser
section. If the unit contains a discharge and suction valve,
verify that the valves are open before attempting to start the
compressors.
RFS units—do not contain service valves.
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