Settings; Pressure Switch Operation; Pressure Switch - Grundfos Hydro Dome CHV 2-50 Installation And Operating Instructions Manual

6. Settings

6.1 Pressure switch operation

The pumps are cut in and out according to the pressures set on
the pressure switches. Each pressure switch is related to one
pump only and not necessarily to the same pump because of the
automatic pump changeover.
A common differential (Δ) pressure (cut-out pressure - cut-in
pressure = Δ pressure) must be set on the pressure switches.
The cut-out and cut-in pressures differ 0.3 to 0.5 bar (cascade
step).
Figure 4 shows the cooperation between the two pressure
switches.
• When a tap is opened, water is drawn from the diaphragm tank
(or bladder tank).
• When the pressure drops to the first cut-in pressure, Pr 1, the
first pump will start.
• If the consumption is still rising and the pressure drops to the
next cut-in pressure, Pr 2, the other pump will start.
• When the water consumption falls, the discharge pressure
rises to the first cut-out pressure, Pr 2, and the controller will
cut out one pump.
• If the consumption is still falling, the last pump will finally fill
the tank and then stop.
Pr 1
Pr 2
Pr 1
Pr 2
Fig. 4

6.2 Pressure switch

The pressure switches are located as shown in fig. 5.
Fig. 5
1. Pressure switch, Pr 1.
2. Pressure switch, Pr 2.
The pressure switches are factory-set to a zero bar inlet
pressure. See the following table.
Hydro
Dome
CHV 2-50
CHV 2-60
CHV 2-80
CHV 2-100
CHV 4-40
CHV 4-50
CHV 4-60
CHV 4-80
CHV 4-100
*
**
The setting can be changed according to the hydraulic conditions
of the pumping system, e.g. when the booster set is connected to
a municipal waterworks or a tank located below the pump.
If pressure switch settings should be changed, the following
settings must be made:
Cascade step
• Cut-out pressure.
Δ pressure
Δ pressure (Δ pressure = cut-out pressure - cut-in pressure).
•
1
2
Fig. 6
1. Cut-out pressure:
+ to increase.
- to decrease.
2. Δ pressure (differential pressure):
+ to increase.
- to decrease.
Factory settings
Pressure switch,
Pr 1
Cut-in Cut-out
pressure pressure pressure
[bar] [bar]
2.5 4.0
3.5 5.0
5.4 6.9
7.4 8.9
1.7 3.2
2.7 4.2
3.4 4.9
5.3 6.8
7.0 8.5
Recommended tank precharge pressure when using the factory
settings.
Check that this pressure does not exceed the maximum tank
precharge pressure.
2
Pressure switch,
Tank
Pr 2
precharge
Cut-in Cut-out
pressure*
pressure
[bar]
[bar] [bar]
2.2 3.7 1.9
3.2 4.7 2.8
5.1 6.6 4.5**
7.0 8.5 6.3**
1.3 2.8 1.1
2.3 3.8 2.0
3.1 4.6 2.7
4.9 6.4 4.4**
6.7 8.2 6.0**
1
9