Well Pump low pressure Issue

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Renli3d

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Jan 15, 2025
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Washington State
Dear forum members,

I would like some advice to diagnose an issue. I have a cycle stop valve system on my well using a 10-gallon diaphragm-style (I assume) tank. When I turn on the cold water from my high flow bathtub faucet, the water comes out at 65 PSI which is what my pressure switch is set to. When the water from the tank is exhausted, the pressure starts to drop and is at 20 PSI within two-three minutes. However, if taking a hot shower using my 2.5GPM showerhead, I can take a 5min shower and the shower seems to hold a steady 50PSI (what the cycle stop valve is set to) so I'm thinking the cycle stop valve is functioning normally. I tried to increase the pressure on the cycle stop valve when at 20PSI by turning the pressure adjustment bolt, but it doesn't affect the pressure.

Once the pressure drops to 20 PSI, it seems to maintain that pressure, fluctuating between 19 and 20 PSI. I ran the pump for about 8-mins and it did not go lower. Water flower out of the bath faucet was reduced but there was no sign of the pump sucking in air, such as sputtering. Sometimes there is sputtering initially just for a second when opening up a faucet though but not while the pump is running.

I have a Grundfos submersible 1.5HP 10GPM pump set at 185' in the well. Well is drilled to 260'. It had no problem pushing 50PSI in the past running through the CSV.

I replaced the start and run capacitors in the well control box. The well pump winding resistance values are 1.85 OHMS and 8.1 OHMS (measured at the control box with 110FT of wire from the box to the well casing plus the 185FT of wire down to the pump). When running, I measured the amperage off the Yellow pump wire and the pump will max out at 9A though it typically runs at less than 8A. When running at 20PSI, the pump is drawing 5.8A. At full load, the pump should be drawing 11.5A.

The Pressure switch is operating normally as it engages the pump at 40 PSI and disengages at 65PSI.
The pump is not short cycling when the water is off.
The pressure is holding steady with the water off, so I don't believe it's a check valve failure.
Once I turn off the water flow, the pressure will rise from 20 PSI back up to 65 PSI at a much slower rate. I haven't timed it, but it takes about 1.5 -2 mins I'm guessing. Previously it was practically instantaneous if I recall correctly.

The entire well/pump system is newly installed and has only 1 year of full-time use. Water usage is high (three ppl who take 20+ min showers, and two others that take 5 min showers) but no lawn irrigation. When the well was drilled, it produced 20+GPM.

Some other possibly useful info:
In Nov, I was out of power and was running the well pump off a generator (non-inverter). When the power came back on, there was a surge that killed my HVAC system and my neighbors washing machine. I did not notice any issues with the water pressure until now though.

The cold water has a lot of air bubbles as if carbonated which was not the case previously. If I pour a glass, the turbidity is high but clears within 15 seconds or so. There is no change to taste. There is no sediment or discoloration.

At this point I'm thinking the issue is either the well pump failing or the well going dry. Strange that the pressure would drop without the pump cavitating if it was indeed going dry though. I tried dropping an ice cube to measure the well depth but I was not able determine when it hit water as it was hitting the side of the well casing.

What are your thoughts?
 
I have my well company scheduled to come out in a few days. They think it could possibly be clogged perforations that are preventing water from reaching the pump. Hopefully that's it! I'll keep you guys updated.
 
From 180' and at 20 PSI that pump should produce about 12 GPM. I also think the pump is starving for water at high flow. Check the flow rate of the tub faucet and it will match the output of the well. When the pump is trying to produce 12 GPM and the well is only making say 8 GPM, the pressure and amps will drop. I would think for the first minute of tub fill the pump will draw 11 amps. As soon as the well level pulls down to the pump should see an abrupt drop in amps to the 5.8 or so. The pump is just delivering what water it can get. The bubbles in the cold water line and the burst of air on first opening are also signs you are drawing the well down.

With a CSV you have the option of using less water without the pump cycling, the same as when a shower is on. You can just restrict the flow with the tub faucet to less the the output of the well and the pressure will stay at 50.
 
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