Did I burn out my pump?

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Irish Mtn

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I have a slow well and I was testing the water volume and pumping gpms so I could set the ball valve output into the cistern. I relied on my PumpSaver to shut it off when the well went dry. When the flow stopped, I ran back to the panel to flip the breaker anyway in less than 1 min. That was yesterday. Today when the well had recovered, I tried it again—but nothing at all. The PumpSaver has a solid green light, but no water flow. Could that short time in run-dry Yesterday been long enough to damage the pump or motor? The pump is in a sleeve that extends 1 ft below it’s bottom. Never done an ohm test before.
Grundfos 1/2 hp 2-wire 230
 

Valveman

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You need a clip around amp meter to see what is going on. Green light yet no water maybe a broken wire or something. A Pumpsaver looks for a 25% drop in amps. When restricting a Grundfos pump with a ball valve the amps will drop considerably. If the pump saver was calibrated with the low amps from the ball valve, it may not see another 25% drop to shut off on dry run when it should?
 

Irish Mtn

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You need a clip around amp meter to see what is going on. Green light yet no water maybe a broken wire or something. A Pumpsaver looks for a 25% drop in amps. When restricting a Grundfos pump with a ball valve the amps will drop considerably. If the pump saver was calibrated with the low amps from the ball valve, it may not see another 25% drop to shut off on dry run when it should?
THX Valveman.
The pumpsaver was at normal calibration and the valve was fully open when I emptied the well--like I've done a number of times before. I will check/redo the connections at the wellhead and pick up a clamp meter. I guess my real question was how long a pump can run dry before it dies--and is it the motor or the pump head that goes.
 

Valveman

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It depends on a lot of things. Plastic floating stage type impellers usually melt before the motor gets hot. Stainless Steel floating stack type impellers usually hold up better than the motor thrust bearing. The cooler the well water and the more natural flow in the well the more time it buys you, but not by much. Low amps means your impellers melted down. High amps means plastic impellers melted and stuck together and/or the thrust bearing in the motor is down. Normal amps means it melted the pipe and is just circulating water in the well.

Rule of thumb I would say you have about 10 minutes before something goes south. But I have seen pumps running like that for weeks or months and when you open a valve they just pump out the hot water and go back to working. Rare but happens.
 

Irish Mtn

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It depends on a lot of things. Plastic floating stage type impellers usually melt before the motor gets hot. Stainless Steel floating stack type impellers usually hold up better than the motor thrust bearing. The cooler the well water and the more natural flow in the well the more time it buys you, but not by much. Low amps means your impellers melted down. High amps means plastic impellers melted and stuck together and/or the thrust bearing in the motor is down. Normal amps means it melted the pipe and is just circulating water in the well.

Rule of thumb I would say you have about 10 minutes before something goes south. But I have seen pumps running like that for weeks or months and when you open a valve they just pump out the hot water and go back to working. Rare but happens.


Update: it was indeed a bad connection at the wellhead. Pump is just fine—ohms are to spec. I now have a new clamp meter in case any new adventures pop up. Thx for your help
 

Banjo Bud

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Ok, glad to hear it’s fixed. But just some info. I have a shallow well pump that ran dry for 1/2 hour and it didn’t hurt it. That was a year and a half ago. I now have a cycle sensor.
 
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