Pump suggestions?

[Jennifer B]

Hi, I am wondering if there is a booster type pump that is designed to purposely turn itself off when it starts to pump air. I understand that some pumps will shut themselves off if they are stressed by pulling air, but I am talking about a pump that is happily designed for that function.

My situation is that I wish to pump water up to a holding tank from two lower tanks that collect rainwater from my roof, and my installer is concerned that when I go to do that pumping (which will probably only need to be done 3-4 times a year) that something could distract me and the pump could finish pumping, suck air and burn out.

There is only electrical power at the top of the system, where the holding tank is, so pushing the water up is not an option.

I can and will put in a mechanical check valve at the bottom of the slope (where the two rain tanks are) so any water in the line won't drain back and cause me to have to prime the system again.

The lift is about 30 feet from bottom of lower tanks to fill line of top holding tank.

I appreciate any suggestions!

 

[Reach4]

A float switch would be the easy cheaper way to do that. You power the pump through the float switch and your on-off switch. That means that you would have to have wires that run down to the float switch.

You cannot reliably pull up 3o ft. You can only count on 25 from the top of the pump to the surface of the water. Running wires to a pump at the bottom is probably not as hard as you think. For 4 times per year, you could even consider an extension cord.

 

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[Valveman]

A Cycle Sensor is designed to shut the pump down when it is running dry. It simply attaches to the power wires going to the pump. When the amp draw is low the Cycle Sensor knows the pump is running dry and shuts the pump off.

 

[hj]

If you can work it out so that the pump inlet pipe is at least 30'high and ends below where the water would be depleted, the pump would not physically be able to pump air.

 

[Jennifer B]

A float switch would be the easy cheaper way to do that. You power the pump through the float switch and your on-off switch. That means that you would have to have wires that run down to the float switch.

You cannot reliably pull up 3o ft. You can only count on 25 from the top of the pump to the surface of the water. Running wires to a pump at the bottom is probably not as hard as you think. For 4 times per year, you could even consider an extension cord.

Hi Reach4, I do not understand the part about not being able to reliably pull up 30 ft. Aren't there well pumps that pull higher than that? I agree about the float switch. I was just trying to avoid having to run wires all the way to the tanks. Thank you for your input.

 

[Jennifer B]

A Cycle Sensor is designed to shut the pump down when it is running dry. It simply attaches to the power wires going to the pump. When the amp draw is low the Cycle Sensor knows the pump is running dry and shuts the pump off.

Hi valveman. This sounds like a very cool device. This may be just what I need. Thank you.

 

[Jennifer B]

If you can work it out so that the pump inlet pipe is at least 30'high and ends below where the water would be depleted, the pump would not physically be able to pump air.

HJ, this sounds like a very sensible idea, but for some reason, I don't seem to be able to get my head around it. For me, sometimes, pictures are so much easier. If you feel like elaborating, that'd be cool. But I think I may pursue the Cycle Sensor idea, if it gets good reviews. Thank you.

 

[Reach4]

Hi Reach4, I do not understand the part about not being able to reliably pull up 30 ft. Aren't there well pumps that pull higher than that?

No. You can push water from great depths, but you can only pull water a limited amount.

The reason is that when you apply a vacuum to water (suck on it) the boiling point rises. The main factor is the vacuum. Usually it is pointed out that a vacuum can only be as strong as the atmospheric pressure. Atmospheric pressure varies. It varies with altitude, and it varies with weather. So 25 ft is usually considered as high as you can reliably pump. And that would be measured from the water surface (not the pickup) to the top pipe or pump.

To pump from deeper, you need to do some pumping below. That can be from a venturi pump down the hole (powered by a second pipe pushing water down) or with a submersible pump powered by electricity. Those are the two that you would normally select from. Then there can be hand pumps and so forth.

Now will it work from 30 ft much of the time? Probably. It depends on altitude and weather. It will probably work more often in Phoenix than in Sedona due to altitude. In Sedona I would not rely on even 25 ft without doing some calculations.

 

[Valveman]

If you make the down pipe so long that a shallow well jet can no longer lift the water, the NPSH will be so low the pump will cavitate. This means it is basically sucking the O molecules right out of the H2O. It would be better to shut the pump off when the amps get low using a Cycle Sensor, that it is to let the pump run without being able to draw from that depth.

See this link.

https://cpkits.com/collections/cycle-sensor-pump-monitors/products/cs1ph1-2hp230v

 

[Jennifer B]

Thank you, Reach4 and valveman for explaining the pulling issue. It turns out that the distance I need to lift the water is much less than I thought. I checked with my laser level, and it is only about 10 feet! (so much for my ability to estimate). This is good news. I am now leaning towards installing a bilge pump in the lower tank, and push the water up to the upper tank. And if I am understanding correctly, the bilge pump will allow any water stuck in the exposed pipes (the pipes that will go up and out of the lower tank) to drain back into my rain tank, so those pipes will not freeze in winter (the rest of the pipes are underground). Hopefully that is right. I was told though, that if the winter gets too cold, and if there is not much water in the tank, I may have to remove the bilge pump from the tank to protect it. Sounds reasonable.