How to install Float Level Switch?

Dear community,

I'm trying to install a water float level sensor to get notified, when a water tank runs dry and am stuck on how to position the sensor.
I got one of those float level sensors from the chinese seller for around 1 buck. If I were to attach the sensor to the bottom of the tank, the wires would be in the water. Is this intended?
I saw some people position the switch at the top of the tank, so only the floating cylinder was under water, as well as some attach it to the side of the tank by drilling a hole in it.

This is probably a very basic question, but is it fine to install such a sensor completely submerged?

Best regards from a fellow student of life.

Your topic was MOVED to its current forum category as it is more suitable than the original

Please post a link to the sensor that you have got

Please show us the type of sensor you bought…
Link or photo at least.

Of course, it's this most basic sensor:

Float Level Sensor

Looks to me like you need to make a hole in the base and poke the thread through so the sensor points vertically upwards, with the wires outside.

edit... like this:


Right, that'd be most unfortunate, since I was hoping for a non-permanent method of installation, due to a lack of trust when adding holes to water tanks :smiley:

So water will seep in and get into those wires?

I've also installed a HC-SR04 ultrasonic sensor to measure the tank level, but really wanted the float level switch as an additional safety measure.

You may be able to use a immersible pressure sensor to get an approximate idea of the water level in the tank. That would be non-invasive.

How? The wires are inside the sensor's barrel. The danger is if you don't do the nuts up tight and use the nylon washer (with some sealant if necessary) you'll lose some of the water.

Sorry, my question was poorly phrased.
If I were to submerse the float sensor, so it rests at the bottom of the water tank, water will get into seep into those wires? Is that, why it's necessary to place it upside down, like you have drawn?

We have no way of knowing what would happen if the whole switch were submerged, but I would guess that the water in the barrel would short the contacts of the switch. The switch is unlikely to be waterproof to water in the barrel, since by design the barrel would / should never have water inside.

edit- Why don't you fill the barrel with water and see what happens. Measure continuity across the outputs with your Ohm meter.

The owner of the tank would no doubt agree. :rofl:

OK, down to the plumbing (or electrical) supplier.

Get a length of PVC pipe, an end cap and the necessary jointing glue. (You are also supposed to use primer.)

Drill a hole in the cap, mount the float sensor on it, and seal it on to the end of the pipe after connecting some cable. The float switch will work either way up (but not sideways, there is a different float switch for that) so you just suspend the pipe in the tank with the float switch pointing down. The only difference is of course which way the reed switch is "on".

If you have sealed it properly, the water will not get in to the pipe (keep the top end out of the water of course :grin:). If you have not sealed it properly you will have to get another float switch later, or try another idea. :thinking:

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Well, not directly, as it is a vacuum sealed reed switch. :grin:

The switch has been fully submerged for a few weeks now, to prevent a waterpump in a greenhouse to run dry and so far, it's working just fine. So it doesn't seem to break immidiately.
But just because it's working so far, doesn't mean it won't break at some point :smiley:

That's a good idea with the PVC pipe

BTW I use those exact sensors a bit…
You may need to pop the ‘C’ circlip off, and invert the loose float ring.
That will swap the N/O - N/C state of the float position.
After confirming the correct operation,mI put a blob of epoxy on the circlip to stop it disappearing.

You can also get sensors that fit horizontally, from a hole drilled in the side of the tank.
The red rubber o-rings will squash & distort, so keep an eye if you overtighten the nylon thread!

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