Grundfos MAGNA3 Manual page 18

4
FLOW
ADAPT
The FLOW
ADAPT
and FLOW , meaning that the pump runs
LIMIT
AUTO while at the same time ensuring that the
ADAPT
flow rate never exceeds the entered FLOW
This control mode is suitable for systems where a
maximum flow limit is desired and where a steady flow
through the boiler in a boiler system is required. Here,
no extra energy is used for pumping too much liquid
into the system.
In systems with mixing loops, you can use FLOW
to control the flow in each loop.
Characteristics and key benefits
• The dimensioned flow for each zone (required heat
energy) is determined by the flow from the pump.
This flow rate can be set precisely in the
FLOW control mode without using throttling
ADAPT
valves.
• When the flow rate is set lower than the balancing
valve setting, the pump will ramp down instead of
losing energy by pumping against a balancing
valve.
• Cooling surfaces in air-conditioning systems can
operate at high pressure and low flow rate.
Note: The pump cannot reduce the flow rate on the
inlet side, but is able to control that the flow rate on the
outlet side is at least the same as on the inlet side, as
the pump has no built-in valve.
18
control mode combines AUTO
LIMIT
Technical specifications
ADAPT
H
value.
H
fac
H
auto_min
ADAPT
Fig. 16 FLOW
The factory setting of the FLOW
where the AUTO
maximum curve. See fig. 16.
The typical pump selection is based on the required
flow rate and calculated pressure losses. The pump is
typically oversized by 30 to 40 % to ensure that it can
overcome the pressure losses in the system. Under
these conditions, the full benefit of AUTO
be obtained.
To adjust the maximum flow rate of this "oversized"
pump, balancing valves are built into the circuit to
increase the resistance and thus reduce the flow rate.
The FLOW
ADAPT
throttling valve, see fig. 17, but does not eliminate the
need for balancing valves in heating systems.
Fig. 17 Reduced need for a pump throttling valve
MAGNA3
25 % Q 90 % Q
max max
Setting range
Q
fac
control
ADAPT
is the flow rate
ADAPT
factory setting meets the
ADAPT
ADAPT
function reduces the need for a pump
Q
cannot