Chiller Dehydration; Inspect Water Piping; Check Relief Valves; Inspect Wiring - Carrier AquaEdge 19XR Start-Up, Operation And Maintenance Instructions Manual

Chiller Dehydration

Dehydration is recommended if 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 or oil
pump motor, even for a rotation check, if the chiller is un-
der dehydration vacuum. Insulation breakdown and severe
damage may result.
WARNING
Starters must be disconnected by an isolation switch before
placing the machine under a vacuum. To be safe, isolate
any starter before evacuating the chiller if you are not sure
if there are live leads to the hermetic motor.
Dehydration can be done at room temperatures. Using a cold
trap (Fig. 12) 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. Connect a high capacity vacuum pump (5 cfm [.002 m
or larger is recommended) to the refrigerant charging
valve (Fig. 2). Tubing from the pump to the chiller should
be as short in length and as large in diameter as possible to
provide least resistance to gas flow.
2. Use an absolute pressure manometer or a digital vacuum
gage to measure the vacuum.
3. If the entire chiller is to be dehydrated, open all isolation
valves (if present).
4. With the chiller ambient temperature at 60°F (15.6°C) or
higher, operate the vacuum pump until the manometer
reads 185 psig (1275 kPa), or a vacuum indicator reads
35°F (1.7°C). Operate the pump an additional 2 hours.
Do not apply a vacuum greater 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, isolat-
ed 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.
5. Valve off the vacuum pump, stop the pump, and record the
instrument reading.
6. 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.
7. 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.
8. Once dehydration is complete, the evacuation process can
continue. The final vacuum prior to charging the unit with
refrigerant should in all cases be 29.9 in. Hg (500 microns,
0.07 kPa [abs]) or less.
Fig. 12 — Dehydration Cold Trap

Inspect Water Piping

Refer to piping diagrams provided in the certified drawings
and the piping instructions in the 19XR Installation Instruc-
tions 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 wa-
terbox nozzles and covers. Water flows through the cooler and
condenser must meet job requirements. Measure the pressure
drop across the cooler and the condenser.
Water must be within design limits, clean, and treated to en-
sure proper chiller performance and to reduce the potential
of tube damage due to corrosion, scaling, or erosion. Carri-
3 /s]
er assumes no responsibility for chiller damage resulting
from untreated or improperly treated water.

Check Relief Valves

Be sure the relief valves have been piped to the outdoors in
compliance with the latest edition of ANSI/ASHRAE Standard
15 and applicable local safety codes. Piping connections must
allow for access to the valve mechanism for periodic inspec-
tion and leak testing.
The standard 19XR relief valves are set to relieve at 185 psig
(1275 kPa) chiller design pressure.

Inspect Wiring

Do not check the voltage supply without proper equipment
and precautions. Serious injury may result. Follow power
company recommendations.
Do not apply any kind of test voltage, even for a rotation
check, if the chiller is under a dehydration vacuum. Insula-
tion breakdown and serious damage may result.
1. Examine the wiring for conformance to the job wiring dia-
grams and all applicable electrical codes.
2. Compare the ampere rating on the starter nameplate to rat-
ing on the compressor nameplate. The overload trip amps
must be 108% to 120% of the rated load amps.
3. The starter for a centrifugal compressor motor must con-
tain the components and terminals required for PIC 5 con-
trols platform. Check the certified drawings.
4. Check the voltage to the components and compare it to the
nameplate values.
5. Ensure that fused disconnects or circuit breakers have
been supplied for the control panel.
18
CAUTION
WARNING
CAUTION