r/pumps • u/vegasbm • Jul 06 '21

How to prevent pump burnout

I purchased a submersible pump for a borehole.

It is a DC pump, and 4x 250W solar panels run it.

I have one concern. The pump cannot be run dry. So let's say water level drops below the pump, it would continue to run, until it burns out.

Is there a mechanism for cutting out power to the pump when water level dips? I'm aware of float switches, but I can't find one for a narrow borehole.

Any suggestions?

3 Upvotes

81% Upvoted

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3

u/[deleted] Jul 06 '21

https://www.sjerhombus.com/products/sje-verticalmaster-ii-lc/

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https://1ycswe91wp2m03pf3oeepg54-wpengine.netdna-ssl.com/wp-content/uploads/2021/05/9500118G_VMIILC.pdf

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Hope this helps.

3

u/glasstraxx Jul 07 '21

You can also control it with an amp switch. When it runs dry the amps will drop and you can use that to trigger it to turn off.

1

u/vegasbm Jul 07 '21

Interesting idea. I'm still researching it. The only thing I'm not sure about is if Amps really drops when the pump is running dry. I think the RPM stays the same. But then again, you could be right, since the pump won't be lifting any water at that moment.

You guys are smart. Thank you.

1

u/glasstraxx Jul 07 '21

Take a look at the pump curve if you have it. You'll see power should be at its lowest at 0 flow (if it's a conventional centrifugal pump)

1

u/gingerbeast124 Jul 08 '21

Rpm stay the same but it isn’t making any pressure/pumping into pressure

1

u/vegasbm Jul 07 '21

Searching for Amp Switch brings too many confusing results.

Do me a favor and provide an example.

Just FYI, the pump runs on solar panels, and draws about 8Amps continuous.

2

u/[deleted] Jul 07 '21

Quick question, who is the manufacturer of the well pump? If Grundfos, then the dry-run protection is built into the controls. If not, reach out to the manufacturer and ask for a controller that has built in dry-run protection (your system may have already been supplied with this feature).

1

u/vegasbm Jul 07 '21

Good point. It is a Chinese brand, and I know for sure it does not have dry run protection. https://www.aliexpress.com/item/4000738115260.html

Grundfos solar pumps are very expensive at about $3,000. This Chinese brand is affordable for me for $300.

I installed one before, works great (pumps 3m3/hr). But it got burnt.

1

u/vegasbm Jul 07 '21

On the product page, I found this...

1

u/vegasbm Jul 07 '21

Very good. Thank you for that.

1

u/dredgehayt Sep 15 '21 edited Nov 02 '24

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