McQuay SEASONCON ALP-037A, Manual, Page: 35 / 43

START-UP & SHUTDOWN
PRE START-UP
1.
2.
3.
4.
5.
With all electrical disconnects open, check all screw or
lug type electrical connections to be sure they are tight
for good electrical contact. Check all compressor valve
connections for tightness to avoid refrigerant loss at
start-up. Although all factory connections are tight
before shipment, some loosening may have resulted
from shipping vibration.
On chilled water installations, check to see that all
water piping is properly connected.
Check the compressor oil level. Prior to start-up, the oil
level should cover at least on-third of the oil sightglass.
Remove the (8) compressor shipping blocks that are
attached to the compressor rails and the base of the
unit. Units ALP-037 thru 078 do not have shipping
blocks.
Check the voltage of the unit power supply and see
that it is within the 10% tolerance that is allowed.
Phase voltage unbalance must be within
6. Check the unit power supply wiring for adequate
ampacity and a minimum insulation temperature rating
of 75c.
1. Double check that the compressor suction and dis- 7. Start the system by moving pumpdown switches PSI
charge shut-off valves are back seated. Always replace and PS2 to the “auto. pumpdown” position.
valve seal caps.
2. Open the manual liquid line shut-off valve at the outlet
of the subcooler.
3.
4.
5.
Check to see that pumpdown switches PSI and PS2 are
in the “manual pumpdown” position. Throw the con-
trol stop switch
to the “on” position.
Adjust the dial on the temperature controller to the
desired chilled water or leaving air temperature.
Allow the crankcase heaters to operate for at least 12
hours prior to start-up.
6. Start the auxiliary equipment for the installation.
7.
8.
9.
10.
11.
Verify that all mechanical and electrical inspections
have been completed per local codes.
See that all auxiliary control equipment is operative
and that an adequate cooling load is available for initial
start-up.
Open the compressor suction and discharge shut-off
valves until back seated. Always replace valve seal caps.
Making sure control stop switch is open (off) and
pumpdown switches PSI and PS2 are on “manual
pumpdown,” throw the main power and control dis-
connect switches to “on.” This will energize crankcase
heaters. Wait a minimum of 12 hours before starting up
unit.
Open all water flow valves and start the chilled water
pump. Check all piping for leaks and vent the air from
the evaporator and system piping to obtain clean, non-
corrosive water in the evaporator circuit.
CAL
Most relays and terminals in the unit control
cen ter are hot with S 1 and the control circuit
disconnect on.
INITIAL START-UP
8. After running the unit for a short time, check the oil
level in each compressor crankcase and check for
flashing in the refrigerant sightglass (see “Maintenance”
on page 36).
9. After system performance has stabilized, it is necessary
that the “Compressorized Equipment Warranty Form”
(Form No. 206036A) be completed to obtain full war-
ranty benefits. This form is shipped with the unit and
after completion should be returned to McQuay Ser-
vice Department through your sales representative.
TEMPORARY SHUTDOWN
Move pumpdown switches PSI and PS2 to the “manual pumpdown” position. After the compressors have pumped down,
turn off the chilled water pump or evaporator fan. It is especially important on chilled water installations that the compres-
sors pump down before the water flow to the evaporator is interrupted to avoid freeze-up.
START-UP AFTER TEMPORARY SHUTDOWN
1. Start the chilled water pump or evaporator fan. 3. Observe the unit operation for a short time to be sure
2. With control stop switch in the “on” position, move
that the compressors do not cut out on low oil pres-
pumpdown switches PSI and PS2 to the “auto. pump-
sure.
down” position.
EXTENDED SHUTDOWN
1. Close the manual liquid line shut-off valves. 4. Move the control stop switch to the “off” position.
2. After the compressors have pumped down, turn off the 5. Close the compressor suction and discharge valves.
chilled water pump or evaporator fan.
3. Turn off all power to the unit and to the auxiliary
equipment.
6. Tag all opened disconnect switches to warn against
start-up before opening the compressor suction and dis-
charge valves.
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