We put a new 1/2 HP submersible pump in our well about 3 weeks ago. It worked fine for about 2 weeks, then it started surging while it's running. When the pressure drops and the pump starts you can here the water in the pipe surging until the pressure builds up and the pump stops.

Checked the current draw on the pump and it's steady at 5.75 amps, voltage at the well head is 240 volts.
There is about 70' of water above the pump in the well.
There is a pitless adaptor in the well and the line runs about 60' to the house and then about another 30' in the house to the pressure tank and pressure switch.
There is no leak at the pitless adaptor.
Pressure switch is set at 40 on 60 off psi.
Static pressure in the bladder tank is 36psi.
Well casing is 6".

The house is 38 years old and I suspect the old pump was original, never had a problem w/it until the check valve in the pump failed, so we decided to replace the whole pump instead of just the check valve. 100' of pipe is a lot to R&R.
TIA, Ken

Surging between the pump and the tank or surging between the tank and a faucet?

Between the pump and the tank.

Since you only have the pump and the piping as possibilities I'd vote for the pump being the problem. Don't see how piping could cause surging, even if there is a leak or an obstruction it wouldn't cause surging.

With 70' for water above the pump it shouldn't be a well or water supply problem.

Don't have a ready reference but 100 foot of rise might be a bit much for 1/2 hp pump. What size was the old pump?

Suggest raising pump about 30'. If that doesn't fix it it must be defective pump.

Not what you wanted to hear I know.

I don't vote for the pump. I'm just intrigued by the term "surge". What do you mean by that? Do you mean you can hear the water running in the pipe? You did say the pump would pump up to the cut off point and shut down, so if the pump is delivering plenty of water, and it seems it is, then I'm not sure what else you would want the pump to do. Is this 1" pipe we are talking about?

I think I would watch my pressure gauge when the pump cuts on. You should get a fairly steady, slow rise of pressure from 40 to 60 pounds. Are you getting that?

Did you replace the old wellpipe? If not, is it plastic or galvanized?

If everything is working well and it is just some noise in the pipes you are talking about, I'd be tempted to count my blessings and let the good times roll.

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I'm just intrigued by the term "surge". What do you mean by that?

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That is a good question. I am assuming a pulsating volume and pressure at a low frequency. Sort of like how someone I know drives. He accelerates and speeds up, then brakes and slows down. Does this repeatedly, even out on the interstate when there are no other vehicles around. He is an idiot.

[QUOTE][What size was the old pump?/QUOTE]
It was also 1/2 hp. I scraped the crud off the old pump yesterday and it was manufactured in 1973, Myers cat # 5B

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I'm just intrigued by the term "surge". What do you mean by that?

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Kind of hard to explain, it sort of sounds like an old steam engine, you can hear the normal flow of water through the pipe for about a second, then it goes SHHHHH for a coupla seconds, then keeps repeating. As the pressure gets higher, near the cut off point it cycles faster and faster until cutoff.

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Is this 1" pipe we are talking about?

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Did you replace the old wellpipe? If not, is it plastic or galvanized?

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Didn't replace any of the piping. There is about 100' of heavy 1" plastic pipe from the pump up to the pitless adaptor. From there, there is about 60' of 3/4" plastic pipe underground to the basement, There it changes to 3/4" copper and runs about 30' to the furnace room where the pressure tank and pressure switch are located.

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I think I would watch my pressure gauge when the pump cuts on. You should get a fairly steady, slow rise of pressure from 40 to 60 pounds. Are you getting that?

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Yes, a slow steady rise, no fluctuations on the gauge.

I'm just trying to figure out what's causing this surging noise and if it's something I should be concerned about. The old pump never did this, and like I said originally this pump didn't do it for the first 2 weeks or so and then it started. Something strange here.

FWIW, I'm retired, I was an industrial electrician and also a diesel-electric powerhouse mechanic, so I've been exposed to a lot of different machinery during my career.

Where do you hear the sound? Around the tank, along the pipe, at the well head? After pump shuts off, does the pressure hold as long as no water is used?

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FWIW, I'm retired, I was an industrial electrician and also a diesel-electric powerhouse mechanic, so I've been exposed to a lot of different machinery during my career.

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You ought to hang around this board. Could be of some use with that kind of background!

I'm going to guess there is some kind of obstruction in your wellpipe and you are hearing the water having to go around/through it, especially considering it would seem to have been there for at least since 1973.

HK, I know just what you are talking about with that guy driving. That kind of stuff can get on your nerves.

Just thought of something else. Would there happen to be a checkvalve near where this sound seems to be coming from?

AND, it might very well turn out to be something strange going on with the pump, but I wouldn't pull the pump unless it stopped pumping.

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Where do you hear the sound?

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Mostly in the pipe coming into the tank. With the cap off the well and listening down hole, I can just barely hear the pump running, nice and smooth, don't hear any of the surging that I hear in the basement at the pipes.

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After pump shuts off, does the pressure hold as long as no water is used?

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Pressure holds good.

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Would there happen to be a checkvalve near where this sound seems to be coming from?

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No, the only check valve is the one in the pump.

Forgot to mention that the pump we installed is a good one, Red Lion from OK city, not an el cheapo or chi-com cheapy.

Suggestion, for diagnostic purposes check bladder. With pump at cut off pressure bled all the air out of the tank to see if you get any water.

Went and tried that, no water outside the bladder.

I erred when I said there was a pause between the surging sounds, there isn't.
It kind of sounds like this: ShhhhhhhhhhhhhhhhhhShhhhhhhhhhhhhhhhhhShhhhhhhhhhh hhhhhhh
It's more pronounced at the start and then tapers off before it repeats.
I typed it in Word with larger letters to start and then put smaller and smaller letters to try and demonstrate the way the sound tapers off before repeating but when I copied and pasted here it put all the letters the same font size.
I was trying to think of a way I could record the sound and post it so it could be listened to, but don't know how I would do that. I don't have a cell phone so can't take a video with or w/out sound.

Oh well, I guess it something we're going to have to live with unless something changes, either for the better or for the worse.

Thanks all for the suggestions.

If it bothers you too much, then replace the pipe. If it doesn't solve the problem, then at least it won't cost an arm and a leg to do. You might also want to disconnect from the pitless adapter and make sure it is not obstructed.

Found it.
Turns out it was the air injector causing the noise in the line, there was no surging, just a noise that makes it sound like it's surging.
Thanks everyone for your suggestions and support.

What air injector?

Must have an air injector associated with a filter.

I would be interested in learning about that.

This is one type. It is by no means the only design.

Air Injector Iron Filters, Terminator Iron filter, Maclean, Patterson, micronizer

The link that jlisenbe posted shows basically what we have. The air injector is simply a venturi that the water goes through and draws air in to be mixed/absorbed by the water. The bypass valve adjusts how much water goes through the injector and that controls how much air is drawn in. The oxygen in the water allows the iron filter to do it's magic.