What is a Sump Pump Float Switch and How Does It Work?


May 27, 2021

If you have a basement, then the chances are that your property is also equipped with a sump pump. Outside of their obvious benefits to basement ownership, there are a few things you should know and understand about your sump pump in case of the event that something goes wrong, and you need the information to execute a quick fix.

One of those pieces of information you may need in the future is an understanding of what a sump pump float switch is, and how it works. Not only that, but you might also need to know what happens in the event of a floating pump switch failure, and how it can be fixed, and avoided in the future.

What Is a Floating Pump Switch?

The white cylinder acts as the sump pump float switch

A floating pump switch is a device within the sump pump that detects flooding within the sump itself. This all hinges on the use of a round float inside the sump that will always be floating at the surface level of the water. If the water within your sump pump begins to rise, then that float will rise along with it.

It’s similar to a float you might find within a traditional cistern, except in this instance, when the float reaches a designated height within the sump, the float switch will automatically be activated, which will then discharge the pumps, flushing away the built-up water and collected liquid inside.

This is normally a totally automated system, and depending on the location of your property where the sump pump is installed, and the frequency at which it fills up thanks to rain or ground moisture, it could empty automatically hundreds or thousands of times a year with no interruption or even notice on your part.

So, what happens when you notice water appearing in your basement as a result of the pumping system failing. What could have made the float switch fail?

Why Do Sump Pump Float Switches Fail?

In reality, there is no one reason for a sump pump’s floating switch to fail. In fact, it can be down to a number of different factors, which can each have their own effects on the inner workings of a sump pump float switch.

Excessive Usage and Old Age

First, your float switch might fail within a sump pump simply due to excessive use and old age. Wear and tear is always a factor when it comes to moving and working parts, and its no different here.

After a great many cycles of the float switch rising and falling within the sump pump itself, you might find that either the tether connecting the float to the switch breaks, or that the float itself can stop reacting to the rise and fall in the water level.

In this situation, one of two things will happen to the sump pump. Either the float switch will break when the tank is being flushed out, in which case the pump will remain operational – so the sump pumps motor will often remain running, even when the tank is empty. In this situation, you could well see your motor in the sump pump burn out.

The other option is that the float switch fails when the pump is turned off. Here, you will find that when the float reaches your pumps designated level to trigger pumping, nothing happens, and you are instead met with a flooded basement.

Mechanical failure

You could also find that the cause for your float switch failing is down to a mechanical failure. The main cause here would be the float itself being caught between the pump and the reservoir wall, rendering it immobile and therefore unable to signal your pump to begin pumping.

This happens because of the vibrations displacing the float during normal operation, and as a result, you may well encounter flooding as the water overflows from your sump pump.

A Power Cut

Another common reason that you might find your float switch not working in a sump pump is a fairly simple one – a power cut. A float switch (and the pump itself) are electrically powered, and in the event that you don’t have a battery backup motor for your sump pump, a power cut can mean that your sump pump fails at some of the most crucial times – like in electrical thunderstorms, leaving you at the mercy of a flooded basement.

All of these are different, but entirely possible reasons that a sump pump float switch might fail on any given day within your basement. Now you know why the float might fail, but what are the consequences?

What Happens if My Sump Pump Float Switch Fails?

There are two very real possibilities you might have to contend with if your sump pump float switch fails and your sump pump is left immobile. Let’s examine what happens if the float switch fails you when locked in the ‘on’ position first.

If your sump pump fails whilst the float switch is set to allow pumping, then initially you might not notice a problem. In fact, most water that enters your pump will be flushed out and away from your property as it should be – but what will eventually happen due to the motor being constantly engaged is that the pump will burn the motor out with constant use.

Sump pumps aren’t designed to be in use constantly – they are engaged when the float switch is pressed, and constant use (especially when the sump pump tanks is dry) is only going to cause damage.

What’s worse is that because the motor has been engaged constantly, you might not have noticed a problem.

So, when there is next a period of heavy rainfall after the motor has burned itself out, you could come downstairs to a flooded basement as well as a motor in dire need of replacement. Not only are you going to have to have your sump pump fixed but now you are going to have to deal with the cost of a flooded basement as well.

A flooded basement is going to be a recurring theme when it comes to failed float switches in sump pumps. In the event of failure when the sump pump isn’t in the ‘on’ position, your sump pump is going to be rendered useless. At no point will the sump recognise that it is full, and have to start pumping.

It’s here that you are going to start having to deal with a flooded basement. Not only are you now facing damaged property and any belongings that might be stored in the basement, but also the damaging effects of damp on the property. Damp can lead to broken brickwork, faulty foundations and the spread of black mould within your property – all factors that could be avoided with a fully functioning sump pump.

How to Avoid a Sump Pump Float Switch Failure?

The easiest way for any homeowner or property owner to avoid or overcome a failed float switch within a sump pump is with routine and scheduled maintenance from experts in the field. Not only will qualified engineers be able to spot a float switch in need of repair on any sump pump, but they will also be able to attend to a burnt out motor before it’s too late.

To make sure that you are fully protected from failure in your sump pump, contact the Basement Sump and Pump team to ensure that you are booked in for regular maintenance and upkeep. Call 0800 019 9949 to talk to our skilled team today.

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