Why is my well pump overpressurizing?

Question

I have a Franklin 3/4 hp submersible pump 100’ deep in my 5” well bore. I just replaced it as it was showing a consistent overload light on my pump controller. I made sure to test it after I pulled it out and I ordered the EXACT same replacement. I connected everything exactly the same (poly pipe, wiring, rope) and lowered it down. It works great.

Here’s the issue:

It fires up for about 30 seconds. I watch the pressure gauge ride to about 75psi and then the pressure switch kicks off. It rests for 30 seconds as the pressure gauge falls, until it hits 40psi and the pressure switch kicks back on.

So about 60 seconds of cycle time.

Nothing else in the system has been changed since the old exact same pump was working fine without over pressure.

The system pumps up the hill 60’ in elevation over 200’ of 1” poly pipe to my 10’000 gallon storage tank. I have watched it during this operation and water is free flowing at a good pressure into the tank. (So I know it’s not a clogged line).

What else could be causing over pressure? How can I stop it from reaching 75psi? Pressure tank? Pressure switch? I feel like if I omitted both it would not stop rising in pressure until it hit 100psi or so (based on how fast my gauge is rising)

Thank you for the help.

Answer 1

If your goal is that it pumps without cycling until the 10,000 gallon tank is filled, you probably need a flow limiter - notably, given the prior pump's demise, a flow limiter also helps with one cause of overload (pumping more than the pump is rated for, causing it to draw too much current.)

Depending on the pressure rating of your well pipe, you may be able to put that above ground where it's easier to retrofit (so long as the pump can't over-pressure the well pipe beyond its rating) - otherwise the safest place for one is right on the pump output (inconveniently down the well.) You'll want a pressure gauge on the pump side of it if above-ground to monitor what the pipe ends up at, and compare with the pipe rating.

I haven't yet bothered with a flow limiter, but when my well is full (100 feet down), my pump exceeds its rated amperage draw (since it's pumping 200 feet less than when the well is drawn down near the pump at 300 feet) so I'm aware of them.

If your goal is merely a longer cycle time rather than beating it to an early grave with 30 second off times, more pressure tank capacity will do that.

Presumably the previous pump was not performing as well as the new "exact replacement" if it was not cycling the pressure switch while filling the large tank, if you don't have any obstructions (partially closed valve, etc.) which are reducing but not stopping flow to the large tank that are new along with the pump.

Alternative approaches would be a VFD pump control (nice, but expensive) to slow the pump down, or a (I despise their hokey marketing) cycle stop valve, which is essentially a leaky pressure regulator that is subject to the same issue flow limiters are of needing to be sure you don't over-pressure your well pipe in front of it (though they don't generally mention that at all in their hokey marketing...)

Least-cost approach would be to reduce the flow to the large tank further, until the off-time is at least one minute. Best way to do that would be first, to lower your pressure switch settings and pre-charge on the tank, since if the pump is only filling the large tank, it has no need to run at very high pressure, given that going up 60 feet is only about 22 PSI of head, and the same pressure tank has more drawdown at lower pressure settings. If that's not enough to get you over a minute of drawdown, partly close the valve to the large tank until it is.

Answer 2

That is a classic sign that your pressure tank or equivalent is water bound or to small. If it worked properly before then you need to address the water bound pressure "tank". The "tank" has some form of compressible media, be it air or some type of membrane. In your description I believe your tank should have air in it, which has apparently been slowly dissolved in the water. Is it possible somebody has tapped the tank above about mid point to get water out? The easiest fix is to turn the pump off, drain the tank, then turn the pump back on. My father fashioned a tire stem valve onto the tank and would occasionally put compressed air in to solve the problem. There is a liquid you can place in the tank that will float and reduce the adsorption of air by the water, it is like an oil film.

Another thing to check is the tank to small for the pump?

Many years ago I changed from a pressure tank to bladders, they worked great for as long as we owned the home.

I would assume you need about 50 PSIG or more, you need to check the tank instructions. The general rule is 2 lb below cut in which is where you set it. The volume of air (pressure related) determines how much water is in the tank. If the pressure is to low it will short cycle like you are stating. To much and it will possibly blow out the excessive air when the water gets low. Check this link out: https://www.youtube.com/watch?v=CPzRpD_Tncc

Answer 3

https://www.rcworst.com/blog/30-50-or-40-60-PSI-What-pressure-to-set-your-system-to

• also from them, youtube how to adjust a pressure switch
  • https://www.youtube.com/watch?v=1VNSv7xVzzU&t=67s
• also if you change the settings on your switch you also need to adjust your pressure tank
  • https://www.youtube.com/watch?v=w21qa2bMUh8&t=33s

I have a Franklin pump... I just replaced it... I connected everything exactly the same...

What else could be causing over pressure? How can I stop it from reaching 75psi? Pressure tank? Pressure switch? I feel like if I omitted both it would not stop rising in pressure

um, yeah. Based on how you worded your question I get the impression you don't have a full understanding of everything that's involved, and that you thought you could just buy an exact replacement pump and assumed by simply replacing just that that nothing else would need to be done. From my link above take them up on Have any further questions about your system call/chat/email to reach an industry expert. your new pump is working fine, it's not too strong you need to check and adjust the rest of the sheat' involved in the system.

you can also google is 70 psi too high for a well pump and what is good pressure for water well.... 30/50, 40/60, whatever makes you happy, but you need to understand everything involved and there are many youtube vids on the topic.

And if you were not mistaken where you said to my 10’000 gallon **storage** tank then you haven't mentioned your ** pressure ** tank setup (or pressure/storage tank) and like was mentioned that is what you need to check on and verify is correctly sized and installed and still has air in it.

https://www.h2oequipment.com/blog/pressure-tanks-size/

You are ALWAYS better having a larger tank than a smaller one.