Grundfos MAGNA3 Manual page 20

4
Constant temperature
This control mode is suitable in heating systems with a
fixed system characteristic, for example domestic
hot-water systems, where the control of the pump
according to a constant return-pipe temperature is
relevant.
Characteristics and key benefits
• The temperature is kept constant.
• FLOW is used to control the maximum
LIMIT
circulation flow rate.
Technical specifications
H
Fig. 20 Constant-temperature control
The inverse control for cooling application is available
from model B.
Temperature sensor
If the pump is installed in the flow pipe, install an
external temperature sensor in the return pipe of the
system. See fig. 21. Install the sensor as close as
possible to the consumer (radiator, heat exchanger,
etc.).
t
F
t
R
Fig. 21 Pump with an external sensor
If the pump is installed in the return pipe of the system,
you can use the internal temperature sensor. In this
case, install the pump as close as possible to the
consumer (radiator, heat exchanger, etc.).
20
t
t
Fig. 22 Pump with an internal sensor
Differential temperature
Select this control mode if the pump performance is to
be controlled according to a differential temperature in
the system where the pump is installed.
Characteristics and key benefits
• Ensures a constant differential temperature drop
across heating and cooling systems.
• Ensures a constant differential temperature
between the pump and the external sensor, see figs
23 and 24.
• Requires two temperature sensors, the internal
Q
temperature sensor together with an external
sensor.
Technical specifications
H
Fig. 23 Differential temperature
F
R
Δt
MAGNA3
Q