McQuay ACZ 045A, Installation, Operation And Maintenance Manual

Page: 78 / 104

78 IOMM ACZ/AGZ-1
Menu #6: Circuit 62 Pressures

The circuit #2 evaporator and condenser refrigerant pressure
readings are displayed under this menu. The calculated minimum and maximum condenser pressure
values are also shown.
Menu #7 : Circuit #l Temperatures

The circuit #I refrigerant temperatures are calculated from their
corresponding pressure sensors and displayed here. If the optional Sensors are not present, the line
item will flash “Open”.
Menu #8 : Circuit #2 Temperatures

The circuit #2 refrigerant temperatures are calculated from their
corresponding pressure sensors and displayed here. If the optional sensors are not present, the line
item will flash “Open”,
Menu#9: Chiller Amps

Displays the present amp draw of the chiller expressed as a percentage of the
unit rated load amps under full load conditions (optional feature).
Menu #10: Compressor Run Hours

The total run hours for each compressor is available under this
menu.
Menu #11: Compressor Starts

The total number of starts for each compressor is available under this
menu.
Menu#12: Air Temperature

Displays the current outdoor air temperature if the optional OAT sensor
is installed on the air cooled chiller and “Lcl” is selected from Menu 23. Also displayed here is the air
temperature received from a network if the “Rmt” OAT select option from Menu 23 is selected.
Control Menus
Menus 13 through 23 are the set point menus. All adjustable control parameters and set points, time
schedules, control options, and alarm thresholds are accessed through these menus.
CAUTION
Any changes to these parameters must be determined and implemented by qualified
personnel with a thorough understanding of how these parameters affect the operation of the
unit. Negligent or improper adjustment of these controls may result in damage to the unit or
personal injury.
Menu #13: Control Mode

One of several automatic and manual operating modes may be selected
from within this menu. Typically, the selected control mode will be Automatic which will allow the
MicroTech controller to handle all compressor and condenser fan staging. Refrigerant circuit #2 may
be locked off while still allowing circuit #1 to stage automatically by selecting AutoCir#1 -Off#2 as the
operating mode. OffCirc#1 -Auto#2 allows the normal staging of refrigerant circuit #2 but circuit #1 is
locked off. Select Manual Staging if manual control is desired. In this operating mode, the condenser
fans are controlled by the MicroTech but the number of stages is determined manually via the keypad.
If manual staging is selected, the second item under this menu indicates the number of active cooling
stages. Use the INCR or DECR keys to increase or decrease the number of active stages.
Menu#14: Leaving Water Set Points

The leaving wafer set points, control band, maximum pull down
rate and water reset options are adjusted from this menu. The first menu item is The Active Set Point
("Active Spt"). The current control temperature is displayed here. The Leaving Chilled Water Set Point
("Lvg Evap") appear towards the top of this menu. These are the set points that will be maintained for
chillers if no reset options are in effect. The Active Control Set Point ("Active Spt") will display the
calculated chilled or heated water temperature to be maintained when one of the reset options is
enabled.
If the 4-20 milliamp reset option is enabled, the controller will reset the leaving chilled water
temperature to a higher value based on a percentage of the Maximum Chilled Water Reset set point
("MaxChWRst"). At 4mA or less, no reset will occur. At 20mA, the chilled water set point will be reset
to a value equaling the Leaving Evaporator Water Set Point ("Lvg Evap") plus the value stored in the
"MaxChWRst". Any milliamp value between 4 and 20mA will cause a proportional value of the