Start And Stop Levels - Grundfos SLV.65 AUTOADAPT Installation And Operating Instructions Manual

4.3 Start and stop levels

4.3.1 Setting the start level
The pump start level may be affected by the
barometric pressure. In the case of long intervals
between start and stop, the start level may differ
from the set level. See examples below.
Example 1: Constant barometric pressure
The pump will start when the liquid level in the pit
has reached the set start level. Then the pump will
run until the liquid level reaches the stop level. When
it stops, the pump will calibrate itself in relation to the
actual barometric pressure. See fig. 7.
Pump running
Barometric pressure
Fig. 7 Example 1: Constant barometric
pressure
Example 2: Rising barometric pressure
If the barometric pressure rises after the pump has
stopped, the pump will register this rise as a rise in
liquid level. The result may be that the pump starts
before the set start level is reached. See fig. 8.
Pump running
Barometric pressure
Fig. 8 Example 2: Rising barometric pressure
Start level set
Stop level
Start level set
Stop level
Example 3: Falling barometric pressure
If the barometric pressure falls after the pump has
stopped, the pump will register this fall as a fall in
liquid level. The result may be that the pump starts
after the set start level was reached. See fig. 6.
Therefore, the distance between the pump stop level
and the inlet to the pit must be at least 50 cm. See
fig. 9.
Pump running
Barometric pressure
Fig. 9 Example 3: Falling barometric pressure
The pump incorporates dry-running
protection via two dry-running sensors
placed on either side of the electronic unit.
If the water level falls below a dry-running
sensor, the pump will stop immediately,
and it cannot restart until the sensors are
fully submerged again.
The sensors must be cleaned at regular
intervals, depending on the deposits of
sludge on the sensors in the pit.
Start level set
Stop level
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