Air and Water cooled inverter chillers and heat pump
D-EOMZC00105-17EN
Operation Manual
40/84
EWAD TZ - EWAD TZ B -EWWD VZ
Air and Water cooled inverter chillers and
heat pump
5.1.4
Alarm Settings
If glycol is present in the water circuits, factory defaults values for the Alarm Limits listed below must be
adjusted:
Parameter
Description
Low Press Hold
Set the minimum refrigerant pressure of the unit. It is generally recommended to set to a value whose saturated
temperature is 8 to 10°C below the minimum active setpoint. This will allow a safe operation and a proper control
of compressor suction superheat.
Low Press Unload
Set lower than the hold threshold enough to allow a suction pressure recovery from fast transients without
unloading the compressor. A 20 kPa differential is generally appropriate for most applications.
Evap Water Frz
Stops the unit in case the leaving temperature falls below a given threshold. To allow a safe operation of the
chiller, this setting must be adequate to the minimum temperature allowed by the mixture water/glycol present in
the evaporator water circuit.
Cond Water Frz
(W/C units only)
Stops the unit in case the leaving temperature falls below a given threshold. To allow a safe operation of the
chiller, this setting must be adequate to the minimum temperature allowed by the mixture water/glycol present in
the condenser water circuit.
When glycol is used in the plant, always disconnect antifreeze electric heater.
5.1.4.1 Pumps
The UC can manages one or two water pumps for both evaporator and, for W/C units, condenser.
Number of pumps and their priority can be set from the menu in 4.2.4.
The following options are available to control the pump(s):
#1 Only
Set to this in case of single pump or twin pump with only #1 operational (f.e. in case of maintenance on #2)
#2 Only
Set to this in case of twin pump with only #2 operational (f.e. in case of maintenance on #1)
Auto
Set for automatic pump start management. At each chiller start, the pump with the least number of hours will be activated.
#1 Primary
Set to this in case of twin pump with #1 running and #2 as a backup
#2 Primary
Set to this in case of twin pump with #2 running and #1 as a backup
5.1.5
Power Conservation
5.1.5.1 Demand Limit
Demand limit function allows the unit to be limited to a specified maximum load. Capacity limit level is defined
with an external 4-20 mA signal and linear relationship. 4 mA indicate maximum capacity available whereas
20 mA indicates minimum capacity available.
With demand limit function is not possible shutdown the unit but only unload it until minimum admissible
capacity. Demand limit related setpoints available through this menu are listed in the table below.
Parameter
Description
Unit Capacity
Displays current unit capacity
Demand Limit En
Enables demand limit
Demand Limit
Displays active demand limit
Capacity Limit
[%]
Minimum
Capacity
Maximum
Capacity
20
4
Demand Limit
[mA]