EWWQ090G ÷ EWWQ720L - R410A - Water-cooled scroll chillers
EWLQ090G ÷ EWLQ720L - R410A - Condenser less
EWHQ100G ÷ EWHQ400G - R410A - Heat pump scroll chillers
EWAQ-G 075
- 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
Operation Manual
46
EWWQ - EWLQ - EWHQ
EWAQ - EWYQ
Air or Water cooled scroll chiller &
heat pump
D-EOMHW00107-15EN
5.1.6 Pumps
The UC can manages one or two water pumps either for the evaporator either for the condenser.
Number of pumps and their priority can be set from the menu 4.2.4.
Evap Pump Ctrl
Set number of active pumps and priority
Cond Pump Ctrl
Set number of active pumps and priority (W/C only)
Recirc Tm
This parameter indicates the minimum time for which the evaporator/condenser flow switches must be active
before to start the thermostat control
The following options are available for the pumps:
#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
5.1.6.1 Pumps control for W/C units
The UC manages the pumps differently depending on the water circuit that they belong.
The pumps connected to the load water circuit (water circuit connected with the plant) are started
when the unit is set to Enabled and there are compressors available to run. The pumps connected
to the source water circuit (water circuit connected with the cooling tower, water well, etc.) are
started only when at least one of the compressor is started. 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 load water circuit in cooling mode is managed, instead, for the source water
circuit in heating mode and viceversa.
If the condensing control is set as Pressure mode (see section 5.4) the pumps connected to the
source water circuit are managed in a different way. Each pump is related to one of the two
refrigerant circuits and it is started automatically only when required to guarantee the condensing
target.
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.
5.1.6.1 Pumps control for A/C units
In this case the UC only manages the pumps connected to the load water circuit. Lead pump is
started when the unit is set to Enabled and there are compressors available to run.
Depending on the HMI setting pumps are managed differently.
In case of twin pumps in case of flow loss, the UC will try to change over between the lead and the
standby pump to avoid flow loss alarms.
When the unit is disabled the pump is kept running for additional Recirculate Timer delay.
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 0.
