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
Operation Manual
38
EWWQ - EWLQ - EWHQ
Water colled scroll chiller &heat pump
D-EOMWC01203-15EN
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.
Setpoint Reset by Evaporator Return Temperature
The active setpoint is calculated applying a correction that depends on the evaporator entering
(return) water temperature
If the unit works in heat pump mode with water inversion the correction depends on the condenser
entering (return) water temperature.
When the evaporator/condenser
ΔT becomes lower than the SRΔT value, an offset to the LWT
setpoint is increasingly applied, up to the MR value when the
ΔT is equal to zero
MR
Max Reset
AS
Active Setpoint
LWT SP
LWT Setpoint
Signal
4-20 mA Analog input singal
MR
Max Reset
AS
Active Setpoint
SR
T
Start Reset DT
LWT SP
LWT Target
4mA
20mA
Signal
AS
LWT SP
LWT SP - MR
MR
Heat Pump Mode
4mA
20mA
Signal
AS
LWT SP
LWT SP + MR
MR
Chiller Mode