What happens when you use a pump below the range for which it is rated?

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Reach4

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Pump will be less power-efficient. Pump could have upthrust problems. http://www.franklin-electric.com/franklin-aid/why-submersible-motors-fail-part-2.aspx Search for upthrust submersible pump in your favorite search engine.

Rather than just looking at tables (which are easier), also look at pump curves. Expect to see lines marking recommended operation. Remember that the head is the sum of the raising of the water + head from water pressure at 0.434 PSI/ft + dynamic head, which is due to friction and is usually fairly small.

If your pressure switch is set for 30-50 PSI, you also want to ask what happens if you run it at 30.

Did you look at the links I sent?
 
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Boyblue

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Pump will be less power-efficient. Pump could have upthrust problems. http://www.franklin-electric.com/franklin-aid/why-submersible-motors-fail-part-2.aspx Search for upthrust submersible pump in your favorite search engine.

Rather than just looking at tables (which are easier), also look at pump curves. Expect to see lines marking recommended operation. Remember that the head is the sum of the raising of the water + head from water pressure at 0.434 PSI/ft + dynamic head, which is due to friction and is usually fairly small.

If your pressure switch is set for 30-50 PSI, you also want to ask what happens if you run it at 30.

Did you look at the links I sent?

This isn't something I plan to do, there are a lot of pumps that meet my requirements. I just wondered.

I did look at both of those pumps. couldn't find specs on the Franklin (not even on their site). The Bruiser is on my list (probably tops).
 

Boyblue

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This isn't something I plan to do, there are a lot of pumps that meet my requirements. I just wondered.

I did look at both of those pumps. couldn't find specs on the Franklin (not even on their site). The Bruiser is on my list (probably tops).
 

Boyblue

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Didn't want to paint the whole board with aqua peace signs :) and this question sorta fits the whole pump rating thing.

At 20 ft this 15 GPM Franklin pump (15JV05P4-2W230) puts out 14GPM at 40 psi but only 10GPM at 50 psi. Most of the pumps I've looked at have a 1 gallon difference from 40 to 50 psi. Just thought it was interesting & wondered why?
 

Reach4

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The first graph is a portion of a 15 GPM pump curve for the Franklin J-series. The left axis is in feet of head.
The table is the feet of head resulting from a given number of feet that the water is being lifted (columns) and the PSI at the pressure gauge (rows). This will maybe give a better picture.

The bottom curve on the graph is for 1/2 HP 4-stage pump. You can also see the 3/4 6-stage pump above it. This whole graph is is 15 GPM pumps, which means 15 GPM is in the nice efficient part of the curve. If you look at similar curves for 10 GPM pumps (bottom graph), you will find that the pressure changes less for a given change in head. The 1/2 HP 10 GPM is 6-stage, and the 3/4 is 8-stage.
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Reach4

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The Bruiser is on my list (probably tops).
See https://terrylove.com/forums/index....gest-other-possible-improvements.58913/page-2 post #31 for a negative opinion on Bruiser.

I don't know if that opinion was from pumps set 300 ft down, or what. Craigpump does not like plastic pumps due to bad experiences. Others find them OK with the warning to not overtighten the pipe into them.

Also, on looking at pump head graphs, note https://terrylove.com/forums/index.php?posts/436134/ post #14 points out an additional head factor that should be considered with a CSV. Seven PSI would be 16 ft of head.
 
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