Nothing is more annoying than a basement full of water where the vacuum refuses to start or stops halfway through. In this guide, we discuss the most common causes of startup problems and provide practical solutions to get your space dry again.
Why doesn't my flat vacuum cleaner start?
A submersible pump is a precision instrument. Unlike a standard submersible pump, a submersible pump often has to respond to very low water levels. If the pump doesn't start, the cause is usually the control unit or power supply. First, check whether the float or sensor moves freely and is not dirty.
In models with an electronic sensor, limescale or dirt on the electrodes can prevent water contact from being registered. You can read more about this in "Flat vacuum cleaner with internal float vs. external float: What's the best choice?" .
Flat suction submersible pump
The pump stops too early: The problem of air entrapment
A common complaint is that the pump starts but stops before the water is completely gone. This is often caused by an airlock. When air gets into the pump housing, the impeller can't build up pressure to force the water upward. The pump then runs, but doesn't move any water.
Solutions for airlock
- Tilt the pump: Submerge the pump in water at an angle to allow air to escape from the pump housing.
- Air Release Valve: Check that the small hole on the side of the pump is not clogged; this is to allow air to escape.
- Check valve: If water flows back into the hose when the pump stops, it may reactivate or block the sensor.
For a step-by-step approach to flooding, we recommend the article "Flooded Basement? Step-by-Step Plan for Pumping a Mop Dry ."
Problems with the sensor setting
Flat vacuums that need to pump dry often operate with highly sensitive sensors. If the sensor is set too high, too much water will remain. If it's set too low, the pump can run dry and become damaged. For automatic operation at extremely low water levels, an external sensor is often the best solution.
Crab Float Water Sensor 3mm
Want to learn more about the technical aspects of installation? See "Maintenance and Installation of a Flat Suction Pump" for tips on maintaining your equipment.
Frequently asked questions about flat suction cups
How low can a flat suction dredger pump away water?
A good vacuum cleaner can remove water down to a residual level of about 1 to 2 millimeters, provided the surface is flat. This is also called "mop dry."
My pump hums but does nothing, what's wrong?
This often indicates a blocked impeller. A small stone or dirt may be stuck. See " How to clean the impeller of a flat vacuum cleaner after use?" for cleaning instructions.
Can I connect a regular garden hose to my flat vacuum cleaner?
Yes, that's possible, but keep in mind that a thin hose will significantly limit the capacity. For best results, use a hose with a larger diameter. Read more in Connecting the right hose to your flat vacuum: Diameter and couplings .
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Connecting the correct hose to your flat vacuum cleaner: Diameter and couplings
Flat suction dredgers for flooding and basement drainage