Positioning The Pressure Sensor - Grundfos CU 301 Notice D'installation Et De Fonctionnement

Operating relay
RELAY, terminals 8 and 9:
Terminals 8 and 9 (RELAY) are used for the
connection of an external signal transmitter (sound
or light).
The operating relay is a normally open (NO) contact
when the pump is not running, and closes while the
pump is running.
• Maximum current: 0.5 A.
• Maximum voltage: 230 VAC.
PUMP
POWER
PE
PE
Electrical connection of the operating
Fig. 3
relay
6

2.3 Positioning the pressure sensor

Pressure losses often cause inconvenience to the
user. CU 301 keeps the pressure constant in the
place where the pressure sensor is positioned. See
fig. 4.
RM85-3021-25-1024
DC 24 V
AC 250 V 16 A
8 5
7 4
1 2
MADE IN POLAND
4080
In fig. 4, tap 1 is placed close to the pressure sensor.
Therefore, the pressure is kept nearly constant at tap
RM85-3021-25-1024
DC 24 V
1, as the friction loss is small. At the shower and tap
AC 250 V 16 A
8 5
7 4
2, the friction loss is bigger. This, of course, depends
1 2
on the pipes. However, old and furred-up pipes may
cause inconvenience due to friction loss.
MADE IN POLAND
4080
Example: A person is in the shower. Tap 2 is
opened. The increased flow causes pressure loss in
the pipe, and even though CU 301 is keeping the
pressure constant at the pressure sensor, the person
in the shower feels the pressure loss.
If the pressure sensor is placed closer to the shower
tap, CU 301 increases the pressure when the flow
rate is increased. Then the pressure at the shower
and tap 2 is kept constant, but the pressure at tap 1
is increased.
Therefore, we recommend that the pressure sensor
is positioned as close to the places of consumption
as possible.
Fig. 4
Tap 2
Tap 1