Selecting Pump Control Mode - Grundfos MIXIT Installation And Operating Instructions Manual

7.12 Selecting pump control mode

Main menu > Settings > Setpoint > Pump setpoint
Once connected, MIXIT takes control of the pump. From then on all
pump settings are made via MIXIT. Depending on the application,
MIXIT is factory-set to the following pump control modes:
• Radiator heating system: Proportional pressure
• Underfloor heating system: Constant pressure
• Air handling unit: Constant curve/constant speed
• Cooling: Constant flow.
To change the control mode do as follows:
1. Press Control mode to set the desired control mode. Press OK
to save.
2. Press Head duty point to set the desired duty point. Press OK
to save.
3. Press Flow duty point to set the desired duty point. Press OK
to save.
This menu is only available in proportional-pressure mode.
7.12.1 AUTO
ADAPT
H
A
1
H
auto_min
A
AUTO control
ADAPT
AUTO is a form of proportional-pressure control where the
ADAPT
control curves have a fixed origin, H
enabled AUTO , the pump will start with the factory setting,
ADAPT
H , corresponding to approx. 55 % of its maximum head, and
set1
then adjust its performance to A1. When the pump registers a lower
head on the maximum curve, A2, the AUTO
automatically selects a correspondingly lower control curve, H
the valves in the system close, the pump adjusts its performance to
A3.
Manual setting of the setpoint is not possible.
We recommend the AUTO
ADAPT
systems, especially in systems with relatively large pressure losses
in the distribution pipes, and in replacement situations where the
proportional-pressure duty point is unknown.
H
set1
H
set2
A
3
2
Q
. When you have
auto_min
function
ADAPT
set2
control mode for most heating
7.12.2 Proportional-pressure curve
When the pump control mode is set to proportional pressure, the
pump performance is automatically adjusted to the actual heat
demand in the system by following a proportional-pressure curve
within the pump's maximum and minimum proportional curve.
H
Proportional-pressure curve
Proportional pressure is suitable for systems with relatively large
pressure losses in the distribution pipes. The pump head will
increase proportionally to the flow in the system to compensate for
the large pressure losses in the distribution pipes.
We recommend that you select this control mode in radiator heating
systems.
7.12.3 Constant-pressure curve
The pump performance is automatically adjusted to the actual heat
demand in the system by following a constant-pressure curve within
the pump's maximum and minimum constant curve.
H
Constant-pressure curve
. If
Constant pressure is used in systems with relatively small pressure
losses. The pump head is kept constant, independently of the flow
in the system.
We recommend that you select this control mode in underfloor
heating systems.
Q
Q
33