Inspect Water Piping; Check Safety Valves; Check Purge Compressor Operation - Carrier AquaEdge 19DV Series Start-Up, Operation And Maintenance Instructions Manual

CAUTION
Do not start or megohm-test the compressor motor or any
other pump motor, even for a rotation check, if the chiller is
under dehydration vacuum. Insulation breakdown and se-
vere damage may result.
WARNING
Power to the motor and VFD must be disconnected by an iso-
lation switch before placing the machine under a vacuum. To
be safe, isolate input power 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. 17) may substantially reduce the time required to com-
plete the dehydration and is recommended should the unit be ex-
posed to liquid moisture. 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 and heating of
the water in the water circuits of the chiller to approximately
100°F (38°C) may be required.
Fig. 17 — Dehydration Cold Trap
Perform dehydration as follows:
1. Connect a high capacity vacuum pump (5 cfm [.002 m
or larger is recommended) to the refrigerant vacuum/
charging valve (Fig. 2). Tubing from the pump to the
chiller should be as short in length with a minimum diam-
eter of 0.5 in. (13 mm) and as large in diameter as possible
to provide least resistance to gas flow.
2. Use an absolute pressure manometer or a electronic
micron gage 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.
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 29.8 in. Hg (vac), –14.63 psig (–100.9 kPag), or a
vacuum indicator reads 35°F (1.7°C). Operate the pump
an additional 2 hours.
5. 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 evap-
oration (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.
8. If the reading continues to change after several attempts,
perform a leak test (maximum 45 psig [310 kPa] pressure).
Locate and repair the leak, and repeat dehydration.
9. 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.

Inspect Water Piping

Refer to piping diagrams provided in the certified drawings
and the piping instructions in the 19DV Installation Instruc-
tions manual. Inspect the piping to the evaporator and condens-
er. Be sure that the flow directions are correct and that all pip-
ing specifications have been met.
Piping systems must be properly vented with no stress on wa-
terbox nozzles and covers. Water flows through the evaporator
and condenser must meet job requirements. Measure the pres-
sure drop across the evaporator 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. Carrier as-
sumes no responsibility for chiller damage resulting from un-
treated or improperly treated water.

Check Safety Valves

Be sure safety valves have been piped to the outdoors in com-
3 /s]
pliance with the latest edition of ANSI/ASHRAE Standard 15
and applicable local safety codes. Piping connections must al-
low for access to the valve mechanism for periodic inspection
and leak testing.
The standard 19DV relief devices are set to relieve at 57 psig
(393 kPa) chiller design pressure. To avoid potential rupture
the chiller should never be pressurized above 45 psig (310 kPa)
for any testing purpose.

Check Purge Compressor Operation

Enter Quick Test menu (under Main Menu) and select "Quick
Test Purge Comp." Connect a pressure gage to purge compres-
sor inlet Schrader valve (suction is top fitting).
The purge system is shown in Fig. 18. The reading should be
about 0 ± 0.25 psig (–15.6 to –14.3°F) [0 ± 1.724 kPa (–26.5 to
–25.7°C)]. If not, adjust the purge expansion valve in the
R-134a purge compressor circuit until the reading is correct.
NOTE: This step should only be performed if the purge is not
working correctly. The installation of the gage will result in a loss
of refrigerant and the charge of R-134a is a very small quantity af-
fecting the operation of the purge. The charge should be weighed
into this circuit using a charging cylinder or similar device.
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CAUTION