7
II. REFRIGERANT CHARGE DETERMINATION AND
ADJUSTMENT
To avoid possible injury, explosion or death, practice
safe handling of refrigerants.
WARNING
COOLING CYCLE:
The method to insure that the heat pump/cooling system is
properly charged is by weighing in the amount of refrigerant
specified on the outdoor sections nameplate, with additional
adjustments for line size, line length, and other system compo-
nents.
SYSTEMS WITH MORE THAN 7.6 METERS OF REFRIG-
ERANT LINE REFRIGERANT Allowance
Systems having more than 7.6 m of interconnecting refriger-
ant lines require an additional charge allowance of R410A per
Table II.
NOTE - When installing systems were the indoor outdoor
sections are separated by more than 7.6 meters, note the
maximum elevation separation limitations per the diagram in
the LOCATION section of these instructions.
Allowance (R410A) gram/meter 20.5
LINE
O. D. (mm)
LIQUID
LINE
SUCTION
LINE
6.4 20.5
9.5 54.0
12.7 106.0
15.9 173.0 3.8
19.1 5.6
22.2 7.4
28.6 14.0
34.9 20.5
TABLE II - Line Charge
SUPERHEAT METHOD :
1. With both base valves fully open, connect a set of ser-
vice gauges to the base valves’ service port, being care-
ful to purge the lines.
2. Allow the system to operate at least 10 minutes or until
the pressures stabilize.
3. Temporarily install a thermometer on the suction (large)
line near the condensing unit’s base valve. Make sure
that there is good contact between the thermometer and
the refrigerant line and wrap the thermometer and line
with insulating tape to assure accurate readings.
4. Determine the systems superheat as follows:
a. Read the system’s suction pressure, then using Table
III determine the system’s saturated suction tempera
ture.
b. Read the suction line temperature.
c. The system’s superheat = the suction line tempera
ture - the saturated liquid temperature.
615 -3.3
641 -2.2
668 -1.1
695 0
724 1.1
753 2.2
783 3.3
813 4.4
847 5.6
879 6.7
912 7.8
946 8.9
SATURATED SUCTION
TEMPERATURE °C
SUCTION
PRESSURE KPa
TABLE III - Saturated Suction Pressure (R410A)
5. Refer to Table IV for the proper system superheat. Adjust
the charge as necessary by adding charge to lower the
superheat or bleeding the charge to raise the superheat.
6. Remove the service gauge set’s lines carefully - Escaping
liquid refrigerant can cause burns.
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