Chiller Dehydration; Inspect Water Piping; Check Optional Pumpout Compressor; Water Piping - Carrier 23xl 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.
Do not start or megohm-test the compressor motor or oil
pump motor, even for a rotation check, if the chiller is
under dehydration vacuum. Insulation breakdown and
severe damage may result.
Inside-delta type starters must be disconnected by an isola-
tion switch before placing the chiller under a vacuum
because one lead of each phase is live with respect to
ground even though there is not a complete circuit to run
the motor. 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. 36) 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
3
[.002 m /s] or larger is recommended) to the refriger-
ant charging valve (Fig. 2A and 2B). 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 wet bulb vac-
uum indicator to measure the vacuum. Open the shut-
off 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.
3. If the entire chiller is to be dehydrated, open all isola-
tion valves (if present).
4. With the chiller ambient temperature at 60 F (15.6 C)
or higher, operate the vacuum pump until the manome-
ter reads 29.8 in. Hg vac, ref 30 in. bar. (0.1 psia)
(–100.61 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 (.56 C) on the wet
bulb vacuum indicator. At this temperature and pres-
sure, 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.
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.
Dehydration is recommended if
Fig. 36 — Dehydration Cold Trap
Inspect Water Piping —
vided in the certified drawings and the piping instructions in
the 23XL 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. Water flows through the cooler
and condenser must meet job requirements. Measure the pres-
sure drop across the cooler and the condenser.
Water must be within design limits, clean, and treated to
ensure proper chiller performance and to reduce the poten-
tial of tube damage due to corrosion, scaling, or erosion.
Carrier assumes no responsibility for chiller damage result-
ing from untreated or improperly treated water.
Check Optional Pumpout Compressor Water
Piping —
If the optional pumpout storage tank and/or pum-
pout system are installed, check to ensure the pumpout con-
denser water has been piped in. Check for field-supplied shut-
off valves and controls as specified in the job data. Check for
refrigerant leaks on field-installed piping. See Fig. 32-35.
Check Relief Valves —
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 inspection and leak testing.
The 23XL relief valves are set to relieve at the 300 psig
(2069 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
diagrams and all applicable electrical codes.
2. On low-voltage compressors (600 v or less) connect a
voltmeter across the power wires to the compressor
starter and measure the voltage. Compare this reading
to the voltage rating on the compressor and starter
nameplates.
58
Refer to piping diagrams pro-
Be sure the relief valves have