Well pump sometimes running at lower capacity - why?

[4lane]

The other day I had a sprinkler on and watched as the pressure went down till it stopped. The pressure dropped to 20psi when the cut-in is set to 40psi. After an hour or so, the pressure tank was back up to 55psi. So, I put on a faucet and watched as it hit 40psi, I could hear the pump come on and raised the pressure to 55. I put the sprinkler back on to see if I could recreate the original issue and eventually, the tank will loose pressure without the pump coming on to fill it.

As a start, I replaced the pressure regulator in case it was giving a faulty signal, but there was no improvement. Then I ran another test where I saw the issue. The pressure was below the cut in 40psi, the pressure regulator contacts were closed, so it was telling the pump to give water. I put my hand on the pipe from the well and I could feel a faint buzz. When the pump is running normally it's a stronger buzz and I can actually hear it.

So, it appears to me that sometimes the pump runs, but minimally, and in those cases it's not pumping enough (or any) water. After 30m or an hour or two, the pump will eventually start running normally filling the tank. Most times the pump runs normally. In fact, seems I've only seen this issue when there is a strong draw on water over a long time.

I'm not well versed in how/if a pump could run but not fully, and then run normally other times. Could there be a blockage on some screen on the pump itself, or is there a problem with the pump itself? Trying to narrow down the issue before pulling it up 250ft. Any insight is welcome!

 

[Reach4]

Do you have a control box? That would be wired between the pressure switch ("pressure regulator") and the pump.

 

[Sponsor]

 

[4lane]

Do you have a control box? That would be wired between the pressure switch ("pressure regulator") and the pump.

A control box? No. The only thing between the pressure regulator and the pump itself is the pump's electrical box.

 

[Reach4]

A control box? No. The only thing between the pressure regulator and the pump itself is the pump's electrical box.

If you are not talking about something bigger than a a 2x4 or 4x4 inch electrical box, that may be a control box with a start capacitor inside. If those get weak, they can make the motor not start immediately. There are other things in a control box besides a capacitor.

 

[4lane]

If you are not talking about something bigger than a a 2x4 or 4x4 inch electrical box, that may be a control box with a start capacitor inside. If those get weak, they can make the motor not start immediately. There are other things in a control box besides a capacitor.

Yes! Here it is! Can I test the capacitor somehow?

 

[Reach4]

Yes! Here it is! Can I test the capacitor somehow?

It might be more trouble than its worth to do that. You can buy a new one almost as easily. You can test for a totally failed unit with an ohmmeter, but to know if one has severely reduced capacity is harder.

Are you electronics-oriented?

Some just replace the whole box.

 

[4lane]

I tested the capacitor, which checked out fine. But I'm not able to check it's full health (via microfarad test). I also tested continuity on the relay triac and coil. Triac showed infinity resistance, while the coil showed continuity. So, all good there.

Sounds like I should just throw in a new capacitor to eliminate that potential problem. Do you think it's more capacitor or pump issue by the sound of my findings?

 

[4lane]

I took the capacitor out. Looks like it's leaking a little electrolyte from one area. A good indication why the pump is on faintly intermittently, and other times pumping normally?

 

[Reach4]

I took the capacitor out. Looks like it's leaking a little electrolyte from one area. A good indication why the pump is on faintly intermittently, and other times pumping normally?

That would explain it. The start capacitor is used on starting.

Click Inbox, above.

 

[4lane]

That would explain it. The start capacitor is used on starting.

Click Inbox, above.

Thanks so much for your insight. I’ll head in this direction tomorrow.

 

[Valveman]

You would be lucky if replacing the starting capacitor fixes it this time. It probably won't fix it next time. The reason your starting capacitor was leaking is because you are starting the pump way too may times. The large demands for long periods of time cause lots of cycling, which destroys the pump, pressure switch (regulator as you called it) and everything else in a pump system, plus causes pressure fluctuations in the house.

 

[4lane]

Yes I’m aware of the potential. But, this is a weekend house that gets minimal water usage. There have been no pressure changes in the house to date. So I’m hopeful the pump is ok and it’s restricted to a capacitor issue.

 

[Bannerman]

There have been no pressure changes in the house to date.

If your pressure switch is set for the pump to start at 30 psi and shut off at 50 psi, then there will be a 20 psi increase while the pump is running, and a 20 psi decrease while the pump is off and water is further consumed.

If your pump's flow rate is say 10 gpm and you are only using 3 gpm while showering, the pump will fill the pressure tank to 50 psi and shut off, but as you are continuing to use 3 gpm, the pressure will soon drop to 40 psi to cause the pump to start again. These pressure fluctuations will be repeated over and over and over as long as less than 10 gpg is being consumed.

 

[Valveman]

Yes I’m aware of the potential. But, this is a weekend house that gets minimal water usage. There have been no pressure changes in the house to date. So I’m hopeful the pump is ok and it’s restricted to a capacitor issue.

Hopefully with minimal use the new capacitor will make it work for a while. But too much cycling means all the smoke in that motor has been used up and it could fail to come on at any time.