Specifications

6
START-UP AND SERVICE
INITIAL CHECK
Do not attempt to start the liquid chiller even
momentarily unit the following steps have been completed.
1. Check all auxiliary components such as chilled liquid
circulating pump, cooling tower if used, air handling
equipment, or other equipment to which the chiller
supplies liquid. Consult the manufacturer
,
s instructions
2. Check safety thermostat. See Safety Thermostat for
adjustment.
3. Backseat (open) compressor suction and discharge
shutoff valves. Close valves one turn to allow
pressure to reach gages.
4. Open liquid line shutoff valves at condensers.
5. Open valves to capillaries of water-regulating valves
(when used)
6. Fill chilled liquid circuit completely with clean water
or other non-corrosive. fluids to be cooled. Bleed
all air out of high points of system.
7. Open supply valve (or fill cooling tower if used ) for
condenser cooling water.
8. Set temperature controller.
9. Check tightness of all electrical connections.
10. Check compressor oil (should be visible in bulls-eye).
11. Be sure unit is fully charged with refrigerant
(see Refrigerant Charge).
12. Be sure crankcase of each compressor is warm
(heaters should be on for 24 hours before starting
compressors).
START-UP
Start-up should be performed only under supervision of
experienced refrigeration mechanic.
1. Open all system valves that may have been closed
during or after charging.
2. Check air-handling equipment, chilled water and
condenser water pumps, and any other equipment
connected to chiller.
3. Start unit by pushing START button.
4. Check all controls for proper operation.
5. Adjust water-regulating valve to most economical
head pressure ( based on relative cost of water and
electricity).
6. Check chilled water leaving temperature to see that it
remains well above freezing.
7. Check compressor oil level (see Oil Charge).
CRANKCASE HEATERS
Heaters are furnished on all compressors to prevent
refrigerant absorption by oil in the crankcase during
shutdown. Located in bottom cover of compressor, heater is
held in place by clip and bracket. Make sure heater is tight to
prevent it from backing out when operating. Heater will burn
out if exposed to air for an extended length of time. Heater is
wired into control circuit by connecting it to normally closed
auxiliary contacts on compressor starter.
Crankcase heaters should be energized at all times when
unit is not in operation. On 50-Hz units. Each heater is 180
watts, 240 volts. Never open any switch that will de-energize
crankcase heaters unless unit is being serviced or shut down
for a prolonged period. These switches include the unit field
power supply switch (unless control circuit power is from
separate source) and the control circuit switch or breaker. If
control circuit power is from separate source, the fused
disconnect must be kept closed. After a prolonged shutdown
or service job, energize crankcase heaters 24 hours before
starting compressors.
COMPRESSOR REPLACEMENT
If a replacement 6-cylinder compressor has center-bank
cylinder head with discharge valve pad facing pump end,
remove the head and install reverse flange head from original
compressor (discharge valve pad toward motor end ).
Center-bank cylinder head cannot be rotated 180 o.
CIRCUIT BREAKERS
One breaker for each compressor provides three-leg
overload protection. Do not bypass connections or increase
size of breaker to correct trouble. Determine the cause for the
trouble and correct before resetting breaker. Throwing off,
then on again must manually reset tripped breaker. See circuit
breaker trip amps in Table 3, Electrical Data. CIRCUIT
BREAKER KITE RESET
HIGH-LOW DUAL PRESSURE SWITCH
One switch provided in each refrigerant circuit See
Table 6.
High-pressure switch-To check, jumper the normally -open
control relay contacts. Slowly close discharge shutoff valve
until compressor shuts down (should be at cutout pressure
shown in Table 5). Reopen discharge shutoff valve.
Compressor should start when pressure drops to cut-in point
shown
Low-pressure switch-To check, close suction shutoff valve
and allow compressor to pump down. It should stop when
suction pressure drops to cutout point shown in Table6.
Compressor should restart automatically when suction
pressure builds up to cut-in point shown.
For winter start control where HS units are coupled with
air-cooled condensers, move low-pressure switch
connection from suction side of system to a pressure tap
liquid line and reset to cutout at 5 psig leaving differential
same (50 PSI). A 1/4in. flare connection is provided on HS
units between liquid line solenoid nd TXV.
NOTE: Check both switches at start-up and least once
each year.