EWWQ090G ÷ EWWQ720L - R410A - Water-cooled scroll chillers
EWLQ090G ÷ EWLQ720L - R410A - Condenser less
EWHQ100G ÷ EWHQ400G - R410A - Heat pump scroll chillers
EWAQ-
- R410A - Air-cooled scroll chillers
EWAQ-
- R410A - Air-cooled scroll chillers
EWYQ-
- R410A - Air-cooled scroll heat pumps
Air and Water cooled scroll chillers & heat pump
Operation
Manual
EWWQ - EWLQ - EWHQ
EWAQ - EWYQ
Air or Water cooled scroll chiller &
heat pump
D-EOMHW00107-15EN
Operation Manual
47
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 4.2.7 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 4.3.1.5.
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 (W/C only)
ΔT (Return),
OAT Reset (A/C only)
The following setpoints are available through the menu 4.2.7:
Lwt Rest Type
Set the Setpoint Reset mode (None, 4-20 mA, Return, OAT)
Max Reset
Max Setpoint Reset (valid for all active modes)
Start Reset DT
Used on Setpoint Reset by Evaporator DT
Setpoint Reset by External 4-20 mA Signal
The active setpoint is calculated applying a correction based on an external 4-20mA signal. 4 mA
corresponds to 0°C correction, while 20 mA corresponds to a correction of the active setpoint as
set in Max Reset (MR). The pictures below shows how is modified the setpoint respectively in
chiller and heat pump mode. The following abbreviations are used.
