Grundfos ALPHA2 GO - Constant Pressure; Proportional Pressure; Autoadapt; Constant Flow

8.2 Constant pressure
In the constant-pressure mode, the pump runs at constant
pressure, which means the head (pressure difference) is kept
constant, regardless of the heat demand (actual number of open
zones). The pump performance follows the selected constant-
pressure curve.
This control mode is especially suitable for underfloor heating
and applications where the pump is used to supply a common
manifold for multiple zones . The head across each zone will remain
constant, independent of how many zones request heat. Thus a
constant flow in each zone will be maintained, independent of other
zones. The selection of the constant-pressure setting depends on
the characteristics of the zones in the heating system and the actual
heat demand.
The curve's setpoint is user defined in Grundfos GO. The setpoint
can be chosen anywhere between the minimum and maximum
constant-pressure curve in intervals of 0.1 m.
H
Q
TM083818
Constant pressure
8.3 Proportional pressure
In the proportional-pressure mode, the pump runs at proportional
pressure, which means the head (pressure) is reduced at falling
heat demand and increased at rising heat demand. The pump
performance follows the selected proportional-pressure curve. This
control mode is especially suitable for applications where the
heat emitters are equipped with a TRV (thermostatic radiator
valve) which controls the flow depending on the room temperature.
At increased flow, the losses in the distribution system (pipes
and fittings) increase, hence the pumps increase the pressure to
compensate and vice versa, hereby maintaining an almost constant
differential pressure across the thermostatic radiator valve.
The proportional-pressure mode setpoint depends on the heating
system's characteristics and the actual heat demand.
The curve's setpoint is user defined in Grundfos GO. The setpoint
can be chosen anywhere between the minimum and maximum
proportional curve in intervals of 0.1 m. The head against a closed
valve is half the setpoint H
set
, although never below 1 m.
H
Q
TM071003
Proportional-pressure settings
8.4 AUTOADAPT
AUTOADAPT is an integrated function in the constant-pressure and
proportional-pressure modes.
AUTOADAPT selects the best control curve under the given
operating conditions. The pump performance is automatically
adjusted to the actual heat demand, that is the size of the system
and the changing heat demand over time, by continuously selecting
either a proportional-pressure curve or constant-pressure curve
within the AUTOADAPT performance range.
H
Q
H
Q
1
2
3
3
4
TM089303
AUTOADAPT
Pos. Description
1 Constant-pressure curve
2 Proportional-pressure curve
3 Setpoint
4 AUTOADAPT performance range
Do not expect an optimal pump setting from day one. If the
power supply fails or is disconnected, the pump stores the
AUTOADAPT setting in an internal memory and resumes the
automatic adjustment when the power supply has been restored.
8.5 Constant flow
In this control mode, the pump maintains a constant flow in the
system independently of the head.
The curve's setpoint is user defined only in Grundfos GO. The
setpoint can be chosen anywhere between the minimum and
maximum flow curve in intervals of 0.1 m
3
/h.
H
Q
Q
set
TM071240
Constant-flow curve
We recommend that you select this control mode if you know the
desired flow rate to the system.
Overview of ALPHA2 GO flow rates:
Pump variant
Lower flow limit
[m
3
/h]
Upper flow
limit [m
3
/h]
ALPHA2 GO XX-40 0.25 2.0
ALPHA2 GO XX-60 0.25 2.5
ALPHA2 GO XX-75 0.25 3.5
ALPHA2 GO XX-90 0.25 3.8
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English (GB)