Start-Up; Operating Principle; Operation - Grundfos PM Rain Installation And Operating Instructions Manual

6. Start-up

1. Open a tap in the system.
2. Switch on the power supply.
3. Check that the "Pump on" and "Warning" indicator
lights illuminate briefly.
– The pump is running.
4. Close the tap.
– A pressure will be built up in the system.
5. Check that the pump stops after a few seconds
and that the "Pump on" indicator light goes out.
The system is now ready for operation.
If a pressure is not built up in the
system within 3 minutes after start-up,
the dry-running protection will be
activated, and the pump is stopped.
Check the priming conditions of the
pump before attempting to restart the
Note
pump.
The pump is restarted automatically if
DIP switch 6 (AUTO RESET) has been
set to "ON" (factory setting), otherwise
the pump can be restarted manually by
pressing [Reset].

7. Operation

When rainwater is available, the PM Rain
automatically starts and stops the pump. This can be
achieved in two different ways:
• On delivery, the unit has a default setting which
can be used in systems with or without a pressure
tank. See section 7.2 Start/stop according to
water consumption.
• In systems with a pressure tank, it is possible to
use the setting described in section 7.3 Start/stop
with 1 bar (100 kPa) differential pressure. This
setting will reduce the pump operating time.

7.1 Operating principle

When rainwater is available, the PM Rain
automatically starts and stops the pump. As long as
the pump can deliver rainwater at a pressure above
2.5 bar (250 kPa), the mains water back-up will
remain inactive. See fig. 7.
If rainwater is no longer available, the PM Rain will
stop the pump when dry running occurs. When the
system pressure drops below 2.5 bar (250 kPa), the
mains water back-up will be activated.
When rainwater becomes available again, the pump
can be restarted manually or automatically:
• Press [Reset]. The PM Rain will restart the pump
to build up pump pressure.
• Wait until the auto-reset function restarts the
pump. See section 8.2.3 Resetting of dry-running
warning.
1
2
3
4
Fig. 7 Principle sketch
Pos. Description
1 Non-return valve
2 Pressure-reducing valve
3 Mains water back-up
4 Double non-return valve
5 Rainwater from pump
6 PM Rain control panel
7 Rainwater outlet
8 Rainwater and mains water outlet
8
7
6
5
9