Pump keeps running but only makes 10 PSI. Turn off and back on and it works fine. Ideas?

[MarkW]

[Note: post below was edited 1 Nov to make clear that this is a submerged well pump]
Greetings. My friend has a 120VAC 1/2 HP submerged deep well pump (age unknown). Normal cut-on is 35 PSI, off at 55 PSI. It had been working well, but now, occasionally, he has very low water pressure (10 PSI, on the gauge near the pressure tank). When I feel the copper line from the pump there's some slight vibration like it is running. Also, the pipe feels >slightly< warm, like maybe the running-all-the-time pump is actually warming the water in the well valve casing a tiny bit. If we turn off the circuit breaker for the water pump and turn it back on, the pump recovers and pumps normally (35-55 PSI). It seems to refill the tank just as fast as you'd expect.
Any ideas what is going on? Do pumps that are near the end of their life die like this (mine never have)? My only theory is that maybe the circuit breaker (or a connection somewhere) isn't providing full voltage/amperage to the pump. The breaker would be suspect #1, because when we reset it, the pump works (for a day or so).

Just change out the breaker? Try something else? Get ready to call someone to swap out the pump?

Thanks for any assistance.

Mark

 

[Reach4]

A deep well jet pump will either have a control valve or regulator. Add these terms to some of your searches.

The hope is that adjusting the regulator or the control valve will help. I have no experience with these, and mainly want to point you toward some terms to help you search.

 

[Sponsor]

 

[Valveman]

I would guess a suction leak. When you shut it off the air burps out of the pump and it will work again.

 

[MarkW]

A deep well jet pump will either have a control valve or regulator. Add these terms to some of your searches.

The hope is that adjusting the regulator or the control valve will help. I have no experience with these, and mainly want to point you toward some terms to help you search.

Reach4,
Thanks for the information. This is a submerged pump, not a jet pump. My wording in the first post wasn't clear, I went back and edited it to clear that up.

 

[MarkW]

I would guess a suction leak. When you shut it off the air burps out of the pump and it will work again.

Thanks, Valveman. I fixed my first post to make clear that this is a submerged pump. Apologies for the confusion.

 

[Reach4]

Breaker seems unlikely, but easy to check. When the pump is misbehaving, check the voltage out of the pressure switch.

 

[Valveman]

Thanks, Valveman. I fixed my first post to make clear that this is a submerged pump. Apologies for the confusion.

Then you maybe pumping the well dry. Check the amps as they will drop by 50% when it starts pumping air.

 

[MarkW]

Reach4, Valveman: Thanks. Those are two easy things for me to check when I go back. I suspect the problem is likely in the pump itself, I'm just having trouble figuring out why a simple impeller pump would start working again just from cycling the breaker off and back on 2 seconds later. Oh, well. I guess the amazing thing is that they work as long as they do.

 

[Reach4]

If you do replace the pump, what diameter is your well and is it steel? With a 4 inch steel-cased well, I would use a 3-inch SQ pump with a flow inducer. Those are available for 115 volts to power with 120 volts.

If you have the space in your breaker box, you could also convert to 240 volts to feed a 230 volt pump.

 

[MarkW]

If you do replace the pump, what diameter is your well and is it steel? With a 4 inch steel-cased well, I would use a 3-inch SQ pump with a flow inducer. Those are available for 115 volts to power with 120 volts.

If you have the space in your breaker box, you could also convert to 240 volts to feed a 230 volt pump.

I didn't measure, but the casing above grade was steel and looked like it was 5". He's very "price sensitive", and I think he'll probably go with a "conventional" 2-wire 120V pump (approx $325). An SQ unit would actually be nice because it is a rural area and electric power sometimes goes out there, and a pump with low startup current surge would reduce costs for a short-term DC powered backup option. But, I don't think that's in his budget.

The well really needs some serious attention. It is an old pit well (so, no pitless adapter) and the pit fills with water when it rains. Well, it fills with water and anything that falls into the water. It's not a great situation.

 

[MarkW]

I just cooked up another possible theory of what is going on: Maybe the pump's filter screen is getting clogged? That would reduce the pressure it puts out (and the volume). When we turn off the circuit breaker, whatever is blocking the screen has a chance to fall away and the pump then works fine until the screen gets blocked again. Anyway, it does match the symptoms.

I don't know how to test this.

Fixing it? Somehow clean out the well? Or, as a stopgap, install a larger screen around the pump to reduce chances that it will get entirely blocked during one run cycle?

 

[Reach4]

I had my pit demolished, and a pitless installed. I scrubbed out my pit with liquid laundry detergent. I became motivated when I saw suds in my water.

To work around the contamination problem put in a sump pump, or if that does not draw down enough, put in a utility pump.

 

[Bannerman]

having trouble figuring out why a simple impeller pump would start working again just from cycling the breaker off and back on 2 seconds later.

When the level of water is pumped down to the pump's inlet screen, the pump will then draw air.

Because pumps are not very effective at pumping air, the air that entered the pump while it is continuing to run, will become compressed, but at lower pressure than the force needed to open the pump's check valve, especially with the weight of water within the discharge line pushing down on the check valve. Since the air can't escape, it will remain trapped within the impeller and will prevent water from entering even while the water level rises again in the well.

Shutting off power to the pump, even briefly, will allow water to reenter the impeller, effectively allowing the pump to re-prime.

Your description does not seem to suggest a pump issue, but does support a well that is being pumped too low. Suggest checking as Valveman advised.