Confounded - Pump Keeps Running At Limit

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Ntcarson

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I've searched extensively for an answer, but can't seem to find a good match for my issue. Thank you for any suggestions!

I have a double-drop jet pump with a 40/60 pressure switch. When I primed it for use this year, it exhibits a strange behavior where it keeps running when it reaches its normal shutoff pressure, 60psi. A few details:
- It cuts on fine at 40psi
- It delivers pressure and builds to 60psi, but doesn't shut off
- If I force off, at the switch, it will stay off until dropped to 40psi
- Pump holds pressure after I force the switch off
- Tank is at 38psi
- I have a shutoff next to the pump, so behavior happens with pump isolated from outbound

What I've tried:
- Clean out the 1/4" hose between pump and switch
- Double check tank pressure
- Adjust the limits on the pressure switch
- Replaced the switch with a new one (the old one was only a season or 2 old)
- Drank more
- Re-aligned my chokras
- Made a sacrifice to the Gods

I'm pretty confused, but anxious to get the pump back up and running for the season. Any advice? Thanks!
 

Reach4

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When the pump keeps running, how high does the pressure rise to?

If it only hits 60 , I would turn down the pressure switch to 35/55 psi. That would typically mean turning the nut on the big screw 1-3/4 turns CCW.
 

Ntcarson

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Thanks guys! It is under the house, so I'll grab the model info next time I crawl under; the depth of piping is around 23 ft.

It is climbing to 61-2 per my gauge, which could be off. I think it is within 1-2 psi of the normal shutoff point (was always just above 60, per the gauge). Before I replaced the switch, I tried backing it off, but probably didn't turn the nut more than 1/2 turn.

After I loosen the big nut, do I need to do any adjustments to the smaller one?

Thanks again!
 

Fitter30

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No
Thanks guys! It is under the house, so I'll grab the model info next time I crawl under; the depth of piping is around 23 ft.

It is climbing to 61-2 per my gauge, which could be off. I think it is within 1-2 psi of the normal shutoff point (was always just above 60, per the gauge). Before I replaced the switch, I tried backing it off, but probably didn't turn the nut more than 1/2 turn.

After I loosen the big nut, do I need to do any adjustments to the smaller one?

Thanks again!
big nut changes the range not the differential. 60-40 that 20 lbs
 

Ntcarson

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Thanks, y'all - that worked!

Just to close the loop. It is an AOSmith Projet C48K2EC11C3 1HP model.

What does it mean that I needed to back the pressure off this season? Is that indicative of a pump losing its gusto or possibly a lower water level in the well?

Thanks again!
 

LLigetfa

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Is that indicative of a pump losing its gusto or possibly a lower water level in the well?
Yes, either/both. The jet on the pump might require cleaning which would require pulling the two pipes out of the well.

The small spring can affect the cut-off. I suggest loosening or completely removing it unless there is less that 20 PSI difference between cut-on and cut-off.

When you loosen the big spring, it will also lower the cut-on and as such the tank precharge may also need to be lowered.
 

Ntcarson

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Can't find any.info for this pump
Here's a pic of the label. Probably an antiquity, drug from the basement of the builder when I made a well part of the deal...
20240514_080939.jpg
 

Ntcarson

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Yes, either/both. The jet on the pump might require cleaning which would require pulling the two pipes out of the well.

The small spring can affect the cut-off. I suggest loosening or completely removing it unless there is less that 20 PSI difference between cut-on and cut-off.

When you loosen the big spring, it will also lower the cut-on and as such the tank precharge may also need to be lowered.
Gracias, LL!
 

Fitter30

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Here's a pic of the label. Probably an antiquity, drug from the basement of the builder when I made a well part of the deal...View attachment 98954
Pump changed to a century motor and another manufacturer with a 67 lb shut off pressure. Shut off discharge valved off. Would a trust a old gauge no. But can ruin a gauge at first reading yes. Not pulling the piping to clean it.
 

Reach4

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If you drop the cut-in to 35 on a jet pump, you would typically set air precharge to 30 psi. If the air precharge is too high, expect a hiccough in the pressure as the pump starts.

It is normally recommended to check air precharge annually. I do it less frequently. Precharge is normally checked with the water pressure zero.
 

Chucky_ott

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The number you posted is the model of the motor, not the pump. The model of the pump might be found on the label which is out of focus in your picture.

Once you find the right pump model, you should be able to find the right specs. It's possible that the pump can't build more than 60psi.

So having your pressure switch cutoff at 60psi is cutting it close. It may have worked for a while but now, for whatever reason, the pump can't reach 60 so it won't shut off with the switch set at 60.

I had a similar issue with my jet pump. It came with a 30-50 switch, but not knowing any better at the time, I changed the switch to 40-60. It worked for one season but not the next. The pump would no longer shut off. And because I wasn't using any water at the time, this caused the water in the pump to overheat. Eventually, the PVC fitting melted and you can imagine the rest.

Turns out that the maximum pressure my pump could build was 62psi.
 
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Ntcarson

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The number you posted is the model of the motor, not the pump. The model of the pump might be found on the label which is out of focus in your picture.

Once you find the right pump model, you should be able to find the right specs. It's possible that the pump can't build more than 60psi.

So having your pressure switch cutoff at 60psi is cutting it close. It may have worked for a while but now, for whatever reason, the pump can't reach 60 so it won't shut off with the switch set at 60.

I had a similar issue with my jet pump. It came with a 30-50 switch, but not knowing any better at the time, I changed the switch to 40-60. It worked for one season but not the next. The pump would no longer shut off. And because I wasn't using any water at the time, this caused the water in the pump to overheat. Eventually, the PVC fitting melted and you can imagine the rest.

Turns out that the maximum pressure my pump could build was 62psi.
I think you hit the nail on the head, Chucky - thank you! I did the same thing a season or two ago. I'll crawl back under there and find the pump info.
 
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