Pumpdown Mode; External Pumpdown Without Xcm25D Integration (Not Available With Zxdy Units)23; Pumpdown By The Unit Controller (Not Available With Zxdy Units); Figure 15: Digital Operation - Emerson Copeland EazyCool ZX Series Application Manuallines

modulates the capacity according to the proportional band. If the pressure is lower than (C16-C17/2)
the Digital compressor switches off.

Figure 15: Digital operation

NOTE: When the digital valve on the compressor is discharged the compressor is loaded.
NOTE: At start-up the valve is energized for Sut/C20 start-up time, ie, time interval with the
digital valve energized before regulation starts. It ranges from 0 to 10 seconds.

2.15 Pumpdown mode

WARNING
Operation below ambient pressure! Fire hazard! Never operate the system
below atmospheric pressure as a flammable mixture could form inside the
system. Make sure that air does not enter the system. Use a separate A2L-
dedicated recovery unit so that the compressor does not have to be used.
CAUTION
System pressure below atmospheric pressure! Compressor damage!
Never operate the system below atmospheric pressure. There is a risk of
malfunction of the controller in deep vacuum operation which can cause
compressor damage.
Pumpdown functionality is provided by the XCM25D controller for ZXMY standard units only. It is not
released for ZXDY Digital units.
NOTE: Depending on the compressor and/or system design an increase of suction pressure
is possible when the unit stops. Therefore, pumpdown operation requires higher differences
between cut-in and cut-out setpoints. These values must be adjusted according to
application.
2.15.1 External pumpdown without XCM25D integration (not available with ZXDY units)
The easiest solution for pumpdown is to install a solenoid valve in the liquid line (not part of the
standard delivery) and to control it directly with the room thermostat or other external devices. The
settings on the unit for compressor cut-in and cut-out (C01 & C02) can easily be adjusted for
pumpdown. The disadvantage of this easy solution is that the controller is not informed that a
solenoid valve is installed and therefore some protection features of the controller, eg, maximum
pumpdown time in case of blocked solenoid, will not work.

2.15.2 Pumpdown by the unit controller (not available with ZXDY units)

In case of pumpdown by the unit controller (available only with ZXMY units) the user needs to install
a solenoid valve in the liquid line (not part of the standard delivery). In addition to the liquid line
solenoid valve a digital input signal from a room thermostat or a case temperature sensor must be
connected to the XCM25D. There are additional terminals available in the unit which allow for easy
connection of additional hardware if required. The wiring diagram also shows these optional features.
The liquid line solenoid valve Y3 can be connected to terminals X1.N & X1.8. The terminals X1.9 &
X1.10 can be used for a room thermostat (connected to DI3).
AGL_Unit_ZX_A2L_E_Rev00 23