Chiller Dehydration; Inspect Liquid Piping; Inspect Refrigerant Cooling Lines - Carrier AquaEdge 23XRV Start-Up, Operation And Maintenance Instructions Manual

Chiller Dehydration —
the chiller has been open for a considerable period of time, if
the chiller is known to contain moisture, or if there has been a
complete loss of chiller holding charge or refrigerant pressure.
CAUTION
Do not start or megohm-test the compressor motor, even
for a rotation check, if the chiller is under dehydration vac-
uum. Insulation breakdown and severe damage may result.
Dehydration can be done at room temperatures. Using a
cold trap (Fig. 44) may substantially reduce the time required
to complete the dehydration. The higher the room temperature,
the faster dehydration takes place. At low room temperatures, a
very deep vacuum is required to boil off any moisture. If low
ambient temperatures are involved, contact a qualified service
representative for the dehydration techniques required.
Perform dehydration as follows:
1. Disconnect power from the VFD before placing the
chiller under a vacuum.
2. Connect a high capacity vacuum pump (5 cfm [.002 m
or larger is recommended) to the cooler or condenser
charging valve (Fig. 2-4). Tubing from the pump to the
chiller should be as short in length and as large in diame-
ter as possible to provide least resistance to gas flow.
3. Use an absolute pressure manometer or a wet bulb
vacuum indicator to measure the vacuum. Open the
shutoff valve to the vacuum indicator only when taking a
reading. Leave the valve open for 3 minutes to allow the
indicator vacuum to equalize with the chiller vacuum.
4. If the entire chiller is to be dehydrated, open all isolation
valves (if present).
5. With the chiller ambient temperature at 60 F (15.6 C) or
higher, operate the vacuum pump until the manometer
reads 29.9 in. Hg vacuum (750 microns), 0.1 kPa, or a
vacuum indicator reads 35 F (1.7 C). Operate the pump
an additional 2 hours.
Do not apply a greater vacuum than 29.82 in. Hg vac
(757.4 mm Hg) or go below 33 F (0.56 C) on the wet bulb
vacuum indicator. At this temperature and pressure,
isolated pockets of moisture can turn into ice. The slow
rate of evaporation (sublimation) of ice at these low
temperatures and pressures greatly increases dehydration
time.
6. Valve off the vacuum pump, stop the pump, and record
the instrument reading.
7. After a 2-hour wait, take another instrument reading. If
the reading has not changed, dehydration is complete. If
the reading indicates vacuum loss, repeat Steps 4 and 5.
Final dehydration vacuum should be 29.9 in. Hg vac or
less [500 microns, 0.07 kPa (abs)].
Fig. 44 — Dehydration Cold Trap
Dehydration is recommended if
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8. If the reading continues to change after several attempts,
perform a leak test up to the maximum 160 psig
(1103 kPa) pressure. Locate and repair the leak, and
repeat dehydration.
Inspect Liquid Piping —
provided in the certified drawings and the piping instructions in
the 23XRV Installation Instructions manual. Inspect the piping
to the cooler and condenser. Be sure that the flow directions are
correct and that all piping specifications have been met.
Piping systems must be properly vented with no stress on
waterbox nozzles and covers. Liquid flows through the cooler
and condenser must meet job requirements. Measure the pres-
sure drop across the cooler and the condenser.
Liquid must be clean and treated to ensure proper chiller
performance and to reduce the potential of tube damage
due to corrosion, scaling, or erosion. Carrier assumes no
responsibility for chiller damage resulting from untreated
or improperly treated cooler or condenser liquid.
3 /s]
Inspect Refrigerant Cooling Lines (Q,R Com-
pressors Only) —
condensation using an infrared temperature sensor or tempera-
ture meter. The leaving refrigerant cooling line from the drive
should have a temperature of 95 to 100 F (35 to 38 C) or a tem-
perature that is 3 to 5° F (2 to 3° C) greater than the condenser
refrigerant temperature. If the leaving refrigerant temperature is
colder than these levels, or if condensation is noted on the pow-
er module or refrigerant cooling lines, the isolation valve on the
leaving refrigerant cooling line should be partially closed (typi-
cally about half closed) to help with temperature regulation.
See Fig. 45. Note that the adjustment is more accurate at a
greater load that is fixed for at least 10 minutes, and there
should be no condensation on the tube leaving the power mod-
ule before the orifice.
Fig. 45 — Isolation Valve, Leaving Refrigerant
71
Refer to piping diagrams
CAUTION
Inspect the refrigerant cooling lines for
ADJUST VALVE TO
REGULATE
TEMPERATURE
CONDENSER
a23-1730
Cooling Line