EWWQ090G ÷ EWWQ720L - R410a - Water-cooled scroll chillers
EWLQ090G ÷ EWLQ720L - R410a - Condenser less
EWHQ100G ÷ EWHQ400G - R410a - Heat pump scroll chillers
Water cooled scroll chillers & heat pump
Operation
Manual
EWWQ - EWLQ - EWHQ
Water cooled scroll chiller &heat
pump
D-EOMWC01203-15EN
Operation Manual
37
When the unit is configured as Heat Pump with water inversion the controller inverts the
functioning of the pumps. This means that the pump managed for the primary water circuit in
cooling mode is managed, instead, for the secondary water circuit in heating mode and viceversa.
5.1.7 Power Conservation
The unit controller provides two different functions that allow to limit the chiller capacity.
1. Demand Limit: limits the maximum unit capacity.
2. Lwt Reset: applies an offset to the base water temperature setpoint.
Both function must be enabled through the menu Configure Unit 4.9.1.
5.1.7.1 Demand Limit
Demand limit function allows the unit to be limited to a specified maximum capacity. The capacity
limit is given through an external 4-20 mA signal. The table below reports the unit limitation based
on the 4-20mA signal:
Number of
compressors
Demand Limit Signal [mA]
Maximum unit capacity [%]
Maximum number of
compressors On
2
< 12 mA
100%
2
> 12 mA
50%
1
4
< 8 mA
100%
4
8 mA< < 12 mA
75%
3
12 mA< < 16 mA
50%
2
16 mA< < 20 mA
25%
1
In the Power Conservation 4.2.6 menu are reported the actual unit capacity and actual demand
limit.
Unit Capacity
Displays current unit capacity
Demand Limit
Displays active demand limit
5.1.7.2 LWT Reset
The LWT Reset function applies a variable offset to the base temperature setpoint selected
through the interface from the menu Temperature Setpoints 4.4.
If the unit works in Chiller mode the offset has a positive value, so the new setpoint will be greater
than the base setpoint.
If the unit works in Heat pump mode the offset has a negative value, so the new setpoint will be
lower than the base setpoint.
This offset can be calculated starting from:
External signal (4-20mA)
Evaporator or Condenser
ΔT (Return)
The following setpoints are available through the menu 4.2.6:
Lwt Rest Type
Set the Setpoint Reset mode (None, 4-20 mA, Return)
Max Reset
Max Setpoint Reset (valid for all active modes)
Start Reset DT
Used on Setpoint Reset by Evaporator DT