Emerson 3000 - Manual (Page 46)

Water-Cooled Models—Self-Contained Compressor
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4.4.2 Adjustment
Both pressure thresholds can be shifted simultaneously over a 50psi (345kPa) range (the 35psi
[241kPa] differential remains constant). The ball valve setpoint offset parameter in the Liebert iCOM
Service menu can be adjusted from 0 to 50 PSI (345 kPa) to raise or lower the control band similar to
the pressure adjustment on a water regulating valve. Changing the setpoint offset will adjust the
pressure thresholds for both circuits. Units are factory-set at a 30psi (207 kPa) setpoint offset (30psi
[207 kPa] above minimum). This results in a 220psiA (1517kPa) lower threshold and a 255psiA
(1758kPa) upper threshold pressure.
4.4.3 Startup
The setpoint offset is adjusted to the minimum value during startup, then changes to the set value
once the compressor reaches normal operating pressures. Changes in fluid temperature could cause
pressure changes that do not result in valve movement within the deadband. Fan cycling stats should
be set to prevent continuous fluid temperature swings greater than 10 ° F (5.6 ° C).
4.4.4 Location
The motorized ball valve is located in the condenser fluid return line. Three-way valves are piped in a
mixing arrangement with the common port at the valve outlet.
4.4.5 Manual Control
The valve can be manually set by disconnecting AC power, depressing the manual override button on
the valve actuator and adjusting the valve position with the handle. The motorized ball also can be
controlled through the Liebert iCOM’s Service menu using manual mode to override the normal con-
trol.