Multiaqua MHRC2 - EXV Related Setpoints; EXV Control States

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17.1.1. EXV Related Setpoints.
(Refer Setpoints 9-20, 65-72, 109-110, 199-201, 205, 215, 217, and 230).
These Setpoints were added to provide fi ne-tuning to the testing of the movement of the superheat temperature.
Refer to EXV control logic chart in a previous section.
17.1.2. EXV Control States
The EXV Control States show the status of the compressor’s expansion valve. If the compressor has an
EXV it will be displayed under the Status entry.
To view the EXV status through the Keypad LCD, select Status from the Main Menu and then page to the
EXV screen.
EXV States:
LOCKED OUT The compressor is in a Lockout state.
IS CLOSED The associated compressor is OFF and the valve is closed
PRE-PMPDWN The valve has been in a closed state and the system is now requiring the valve action.
IN STARTUP At startup the valve will remain in this state for the time in Setpoint #20. At that time the state will
be changed to holding, at this point the valve control logic will position the valve.
AT 100% This state will be entered when the valve opening reaches 100%.
IS HOLDING Refer to EXV Logic Chart, superheat is in control zone and ROC is acceptable.
IS OPENING Refer to EXV Logic Chart, superheat is in control zone but rising too fast, ROC less than 1.0.
IS CLOSING Refer to EXV Logic Chart, superheat is in the control zone and the rate of change is acceptable,
ROC greater than –0.5.
LOW SPRHT Refer to EXV Logic Chart, force a course valve adjustment.
OPENING 4x Refer to EXV Logic Chart, superheat is above control zone.
OPENING 2x Refer to EXV Logic Chart, superheat is in control zone but rising too fast, the ROC is greater
than 1.0.
LO PSI OPN Refer to EXV Logic Chart, state indicates that a low suction pressure condition exists. The
suction pressure is less than Setpoint #77 “LOW SUCTION” plus twice the value of Setpoint #79
“LOW SUCT RELOAD” and the superheat is greater than Setpoint #9 “SUPERHT TRGT” plus
twice the value of Setpoint #10 “SPRHT ZONE+-“.
CLOSING 2x Refer to EXV Logic Chart, superheat is in the control zone and the rate of change is acceptable,
the ROC is less than -0.5 and greater than -1.0.
CLOSING 4x Refer to EXV Logic Chart, superheat is in control zone but falling too fast, ROC less than -1.0.
HI LVL CLS This state indicates that a high refrigerant level. This state is entered if Setpoint #109
“HiRefLevel” is active and the superheat is greater than the value of this Setpoint.