58
AGZ 030A through 065A
IOM 686
Manual Operation
Manual operating modes are available to simplify setup and troubleshooting of the unit. Any of the
following manual modes may be selected from the Control Mode Menu.
Note: These manual settings are intended to aid in troubleshooting and should not be
considered to be normal operating modes. The equipment should not be left unattended
during manual operation as the automatic staging controls are disabled. The chiller will
remain in the manual mode until Automatic operation is selected or a problem alarm occurs
which will change back to the “Automatic mode”.
•
ManualOff: Manual unit off.
•
Auto1Off2: Automatic Circ#1, Circ#2 off.
•
Auto2Off1: Automatic Circ#2, Circ#1 off.
•
ManualStaging: Manual Staging, Circ#1 & 2.
Compressor Staging
The AGZ Scroll chiller has two (2) refrigerant circuits and each circuit has two (2) scroll compressors.
When in the Automatic mode and stage 1 of cooling is required, the compressor with the lowest
number of starts will be the first compressor to start. Stage 2 of cooling will start the compressor with
the lowest number of starts in the other refrigerant circuit. Stage 3 of cooling will start the next
compressor with the lowest number of starts regardless of refrigerant circuit. Stage 4 will start the last
compressor.
If a compressor is not available for starting due to a safety, the number of cooling stages will be
decreased and always equal to the number of available compressors for operation. At all times the
second stage of cooling will have a compressor from each refrigerant circuit operating. The exception
to this is when “LOW AMBIENT” is selected and the outside air temperature is below the low ambient
setting. The staging logic will be modified to start the compressor with the lowest starts and stage 2
will start the other compressor on that refrigerant circuit. Both compressors on one refrigerant circuit
will operate at low ambient to improve head pressure control. If additional cooling is required, the
next refrigerant circuit will be started.
On a stage down (4 compressors operating), the compressor with the most run hours will be stopped.
The next stage down will be the compressor on the other refrigerant circuit with the most run hours.
The next stage down will be the compressor with the most run hours.
Head Pressure Control
There are two condenser fans per refrigerant circuit. These fans are cycled on and off according to the
circuit’s condenser pressure. Fan #1 of circuit will start when a compressor in the circuit has started
and the condenser pressure exceeds fan on setpoint (230psig R-22). This fan will not cycle off until
the circuit is stopped. The second fan will cycle on and off to maintain minimum lift pressure. If the
condenser pressure increases rapidly, the second fan will be turned on at 290psig (R-22 setpoint) and
remain on until minimum lift pressure regains control.
Summary of Contents for AGZ 030A
Page 21: ...IOM 686 AGZ 030A through 065A 21 Figure 10 Single point Connection with FanTrol...
Page 22: ...22 AGZ 030A through 065A IOM 686 Figure 11 Single point Connection with SpeedTrol...
Page 23: ...20 WKURXJK LJXUH 8QLW RQWURO 6FKHPDWLF 817...
Page 24: ...24 AGZ 030A through 065A IOM 686 Figure 13 Staging Schematic UNT...
Page 25: ...IOM 686 AGZ 030A through 065A 25 Figure 14 MicroTech Controller Schematic...
Page 26: ...26 AGZ 030A through 065A IOM 686 Figure 15 Unit Control Schematic MicroTech...
Page 27: ...IOM 686 AGZ 030A through 065A 27 Figure 16 Staging Schematic MicroTech...
Page 87: ...IOM 686 AGZ 030A through 065A 87 Notes...
Page 88: ...13600 Industrial Park Boulevard P O Box 1551 Minneapolis MN 55440 USA 612 553 5330...
