I have a 40 foot deep 6 inch drilled well. Currently it has an old 3/4 horsepower jet pump, but it is shedding bits of rusty metal into the return pipe which are getting clogged in the foot valve. Everyone is recommending that if I have to replace the pump, I switch to a submersible, but nobody can say why other than "they are better". What are the actual benefits of a submersible over a jet pump (other than being capable of greater depth which doesn't matter here)? Do I need to get a 3/4 HP submersible, or would a 1/2 be fine since they say they do 12+ GPM at 40 feet?
Plumbing – Choosing the right replacement pump for well
plumbingwellwell-pump
Related Solutions
If the lever you are referring to is on the side of your pressure switch:
Then I unfortunately have not very good news for you. As the name implies, this cuts off the switch entirely when the pressure drops to about 10psi below the cut-in point (eg, most well pumps are set up to turn on at 40 and off at 60psi, so the low-pressure point is about 30psi). It's there to prevent the pump from running dry.
Potential cause: low-yield well
Without any other information, my best guess would be your well is not producing enough water to keep up with demand. This seems to be consistent with your statement that it only happens after 30-45 minutes: there is enough reserve capacity in the well itself to supply you for a while, but ultimately, the rate of water entering the well is lower than the rate you're using water.
The ultimate fix for this is to install a cistern or holding tank that the well pump supplies, and have a second pump in that that actually supplies the house. The cistern is controlled via float (instead of pressure switch) and the well pump is protected by a load-monitoring device (eg: Pumptec by Franklin-Electric) that turns off the pump electronically if it senses no-load. The size of the tank largely depends on how much capacity you want, what the actual yield of the well is, and logically where the tank will go and how big you can fit. Commonly, the cistern is a large cylindrical PVC tank installed in the basement.
Potential cause: undersized pump
The other main cause would be an undersized or under-performing pump that is unable to keep up with demand. The symptom of this would be that the pump runs constantly during use, rather than cycling on and off, and that you generally have a consistently low pressure for that time prior to the low-pressure switch cutting out.
Replacing the pump in this case may help, but if you have a low-yield well then it's a waste of money. Considering it's been happening for 14 years, it seems unlikely this would be something mechanically wrong (I'd expect the condition to worsen over time, or for the pump to have failed by now) and more likely that the pump was undersized, IF you also have the symptoms I described.
What next?
If you can determine the pump is undersized, then replacing it with a larger pump would be one way to remedy the problem (assuming there is no yield problem also).
The next best course of action would probably be be to test the yield of the well. You may be able to do this yourself, but a professional will bring in a much larger pump and test the flow right at the well, bypassing all the pressure controls and inside piping that would interfere with the results.
Of course, seeing as you're selling the house, you'll have to make your on judgement call on what you do or disclose -- advice on that is beyond the scope of this site.
In general, the circuit will look something like this
Though you may need a resistor in line ("in series") with the coil.
The documentation for the float switch says it can directly control a 1 hp pump at 230V, so I'm not sure why you're using the contactor at all. You might be able to simplify the setup, and remove the contactor. Then you'd wire it up like this
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Best Answer
Jet pumps were a great idea when pump motors were terribly unreliable, and you could keep the pump motor out of the well by using one.
These days, that's not true. Likewise, anyone who recommends a "3-wire" submersible is also living in the past. Things have changed. I'd suggest a 2-wire pump (there are 3, but one is the ground, and not counted as per usual - "3-wire" pumps use 4 wires for the same reason.) 3-phase is a different deal and un-applicable to most folks with individual water wells. Personally, I prefer a stainless steel pump.
Advantages of a submersible pump other than greater depth capacity -
If they made them, you could probably use a 1/4 HP pump on that well. Last time I was shopping pumps, 1/2 HP was the smallest they made. You may need a restrictor valve (or orifice/plate) to keep it happy.
In the same counterintuitive manner that fans draw LESS power when restricted, non-displacement pumps also draw less power when restricted, and can draw too much power if unrestricted with low head. The short and simple explanation is that it's doing more work (moving more water) when un-restricted, and doing less work (moving less water) when restricted. Most people not already aware of this won't believe it until it is demonstrated with an ammeter and a valve.
Likewise, if your well can't keep up with 12 GPM you'd want to restrict the pump for that reason.