Control Mode - Grundfos CRE Series Installation And Operating Instructions Manual

9.5 Control mode

You can choose between the following control modes:
• Prop. pressure (proportional pressure)
• Const. pressure (constant pressure)
• Const. temp. (constant temperature)
• Con. diff. press. (constant differential pressure)
• Con. diff. temp. (constant differential
temperature)
• Const. flow rate (constant flow rate)
• Const. level (constant level)
• Const. other val. (constant other value)
• Const. curve (constant curve).
9.5.1 Proportional pressure
The head of the pump is reduced at decreasing water
demand and increased at rising water demand. See
the figure below.
This control mode is especially suitable in systems
with relatively large pressure losses in the distribution
pipes. The head of the pump increases proportionally
to the flow in the system to compensate for the large
pressure losses in the distribution pipes.
The setpoint can be set with an accuracy of 0.1 m.
The head against a closed valve is half the setpoint.
The setting range is between 25 % and 90 % of
maximum head.
For more information about settings, see section on
proportional-pressure setup.
H
H
set
H
set
2
Proportional pressure
Example:
• Factory-fitted differential-pressure sensor.
p
Proportional pressure
Controller settings
For the recommended controller settings, see the
section on the controller.
50
Related information
9.16 Controller (Controller settings)
9.5.2 Constant pressure
We recommend this control mode if the pump is to
deliver a constant pressure, independently of the flow
in the system. The pump maintains a constant
pressure independently of the flow rate.
H
Constant pressure
This control mode requires an external pressure
sensor as shown in the examples below. You can set
the pressure sensor in the Assist menu. See the
section on assisted pump setup. The setting range is
between 12.5 % and 100 % of maximum head.
Example:
• One external pressure sensor
Q
Controller settings
For recommended controller settings, see the section
on the controller.
Related information
9.16 Controller (Controller settings)
9.51 Assisted pump setup
Q
p
p