Pressure Settings - Grundfos PM Rain Installation And Operating Instructions Manual

Pos. B in fig. 4:
To achieve correct operation, the pump must be able
to provide the discharge pressures in the table
below.
Minimum discharge pressure
Start pressure
Start/stop
set
according to
water
consumption*
[bar] [kPa] [bar]
2.5* 250 2.9
3.0 300 3.4
3.5 350 3.9
4.0 400 4.4
4.5 450 4.9
5.0 500 5.4
5.5 550 5.9
6.0 600 6.4
* Default setting.
See section 7.2 Start/stop according to water
consumption.
** See section 7.3 Start/stop with 1 bar (100 kPa)
differential pressure.
See also section 4.4.1 Setting the pressure-reducing
valve.
Pos. C in fig. 4:
The unit should be installed so that the control panel
is visible and easily accessible. Ensure that the inlets
and outlets are connected correctly.
To prevent water from entering the unit,
Caution
do not install the unit so that the cable
connections are pointing upwards.
Pos. D in fig. 4:
No taps must be installed between the pump and the
unit.
6
Operating mode
Start/stop
with 1 bar
(100 kPa)
differential
pressure**
[kPa] [bar] [kPa]
290 3.9 390
340 4.4 440
390 4.9 490
440 5.4 540
490 5.9 590
540 6.4 640
590 6.9 690
640 6.9 690

4.4 Pressure settings

The default setting of the pressure-reducing valve is
2.5 bar (250 kPa). However, it may be necessary to
increase this pressure if a higher pressure is
required, for example in a multi-storey building or
other applications requiring a higher pressure.
Note that the pump start pressure must be adjusted
accordingly. See section 5.1 DIP switches.
Ensure before installation that the pump is capable
of delivering the necessary pressure.
4.4.1 Setting the pressure-reducing valve
There must be no pressure on the
system while the pressure-reducing
valve is adjusted.
Set the pressure-reducing valve by
Note
adjusting the adjustment screw.
Turn clockwise to increase the
pressure and counter-clockwise to
decrease the pressure.
1. Remove the pump cable plug from the PM Rain
unit.
2. Turn off the mains water supply.
3. Depressurise the home outlet piping system by
opening a tap.
4. Close the tap.
5. Remove the PM Rain cover.
6. Install a pressure gauge on the home outlet.
7. Adjust the pressure-reducing valve accordingly.
8. Turn on the mains water supply.
9. Read the pressure gauge. If further adjustment is
necessary, repeat from point 2.
When the pressure-reducing valve has been
adjusted correctly, adjust the start pressure
accordingly. See section 5.1 DIP switches.
10. Refit the PM Rain cover.
11. Insert the pump cable plug into the PM Rain unit.
4.4.2 Aligning pressure settings
The setting of the pressure-reducing valve must not
exceed the pressure setting of the PM Rain control
unit. See section 5.1 DIP switches. If the pressure is
exceeded, rainwater cannot be used on the home
outlet.
Even if the setting of the pressure-reducing valve is
not allowed to exceed the PM Rain control unit
setting, it must be close to the required pressure in
order to deliver mains water at sufficient pressure
when rainwater is not available. Recommended
pressure difference is 10 %.
Example
Required minimum system pressure: 3.5 bar
(350 kPa).
• PM Rain control unit setting: 4 bar (400 kPa)
• Pressure-reducing valve setting: 3.6 bar (360 kPa).