Daikin Pathfinder AWV Installation, Operation And Maintenance Manual page 88

Extended (Seasonal) Shutdown
1. Move the Q1 and Q2 switches to the Manual Pumpdown
position.
2. After the compressors have pumped down, turn off the
chilled water pump.
3. Turn off all power to the unit and to the chilled water
pump.
4. If fluid is left in the evaporator, confirm that the
evaporator heaters are operational.
5. Move the emergency stop switch S1 to the "Off" position.
6. Close the compressor discharge valve and the optional
compressor suction valve (if so equipped) as well as the
liquid line shutoff valves.
7. Tag all opened compressor disconnect switches to warn
against startup before opening the compressor suction
valve and liquid line shutoff valves.
8. If glycol is not used in the system, drain all water from
the unit evaporator and chilled water piping if the unit is
to be shutdown during winter and temperatures below
-20°F can be expected. The evaporator is equipped
with heaters to help protect it down to -20°F. Chilled
water piping must be protected with field-installed
protection. Do not leave the vessels or piping open to the
atmosphere over the shutdown period.
9. Do not apply power to the evaporator heaters if the
system is drained of fluids as this can cause the heaters
to burn out.
Startup After Extended (Seasonal)
Shutdown
1. With all electrical disconnects locked and tagged out,
check all screw or lug-type electrical connections to be
sure they are tight for good electrical contact.
2. Check the voltage of the unit power supply and see that
it is within the ±10% tolerance that is allowed. Voltage
unbalance between phases must be within ±2%.
3. See that all auxiliary control equipment is operative and
that an adequate cooling load is available for startup.
4. Check all compressor flange connections for tightness to
avoid refrigerant loss. Always replace valve seal caps.
5. Make sure system switch Q0 is in the "Stop" position and
pumpdown switches Q1 and Q2 are set to "Pumpdown
and Stop". Throw the main power and control disconnect
switches to "On." This will energize the crankcase
heaters. Wait a minimum of 12 hours before starting up
unit. Turn compressor circuit breakers to "Off" position
until ready to start unit.
6. Open the optional compressor suction butterfly valves,
the liquid line shutoff valves, and compressor discharge
valves.
7. Vent the air from the evaporator water side as well as
IOM 1242-8 • PATHFINDER MODEL AWV CHILLERS
®
from the system piping. Open all water flow valves and
start the chilled water pump. Check all piping for leaks
and recheck for air in the system. Verify the correct flow
rate by taking the pressure drop across the evaporator
and compare to the graphs beginning on
8. Set the chilled water set point to the required
temperature. The system water temperature must be
greater than the total of the leaving water temperature
set point plus one-half the control band plus the startup
Delta-T before the MicroTech
cooling.
9. Under the "Control Mode" menu of the keypad, place the
unit into the automatic Cool Mode.
10. Start the system by moving pumpdown switches to the
"Auto" position.
Flow Switch Installation and Calibration
A thermal dispersion flow switch uses heat to determine
flow and therefore must be calibrated during system startup.
A thermal dispersion flow switch can be an acceptable
replacement for paddle type flow switches and differential
pressure switches but care must be taken regarding wiring.
The thermal dispersion flow switch supplied by Daikin Applied,
shown in Figure 1, comes as a 2 part unit consisting of a flow
switch and an adapter labeled E40242 by the supplier.
Figure 81: Thermal Dispersion Flow Switch and Adapter
Mounting
Figure 82 highlights the position of the electrical connector and
indentation 'mark' on flow switch.
It is recommended, if possible, that the flow switch be mounted
such that the electrical connection and indentation 'mark' are
pointed in the direction of flow as shown in
important that the flow switch be mounted so that the probe is
sufficiently inserted into the fluid stream. It may not be mounted
directly on top or directly on the bottom of a horizontal pipe.
88
Startup and Shutdown
page 42.
III controller will stage on
®
IMPORTANT: Flow switch
MUST be calibrated before
chiller operation. Failure to
properly calibrate the switch
may result in severe chiller
damage and/or void warranty.
Figure 83. It is
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