Grundfos CU 301 Instrucciones De Instalación Y Funcionamiento página 10

The pump speed is reduced until a small pressure
drop is registered. This pressure drop indicates that
water is consumed and the pump speed is resumed.
See fig. Flow detection every 10 seconds during
operation.
If the pump speed reduces without any pressure drop
being registered, this indicates that no water is
consumed. The diaphragm tank is filled with water
and the pump stops.
2
1
10 s 10 s
Flow detection every 10 seconds during operation
Pos. Description
1 Flow detection
2 Pressure
3 Time
System limits
Even though, CU 301 controls the pressure within ±
0.2 bar, bigger pressure variations may occur in the
system. If the consumption is suddenly changed, for
example if a tap is opened, the water must start
flowing before the pressure can be made constant
again. Such dynamic variations depend on the pipes,
but, typically, they will lie between 0.5 and 1 bar.
If the desired consumption is higher than the quantity
the pump is able to deliver at the desired pressure,
the pressure follows the pump curve as illustrated in
fig. Possible pressure variations during constant-
pressure operation.
10
2
1
A
3
7
Possible pressure variations during constant-
pressure operation
Pos. Description
3
Stop
1
+ 0.5 bar
2 Pressure
Start
3
- 0.5 bar
4 Controlling ± 0.2 bar
5 Dynamic variations ± 0.5 bar
6 Flow
7 0.18
3
8
m /h
A Pressure set
5
4
6
8