Replacing well jet pump, Galv. Pipe to PVC

Our very old deep well jet pump is dying. It will never shut off. Plumber came and told us the impellers are shot from the ancient motor. It is reading a pressure of 42psi, but it not enough to cutoff, so it runs and runs.
He quoted $1500 to replace it. I'm going to do it myself. The pump is easily accessible with two galvanized pipes coming from the well to it, and one 3/4" output to the house water supply (bladder tank). But even being galvanized, I'm betting they are going to be a bear to remove.
So in planning ahead (since we will have no water once I begin!), I'm considering just cutting the pipes as close the motor as possible with either a reciprocating saw, or a compressed air metal cutting wheel tool I have. The reciprocating saw with metal blade seems the better choice...?
I'm wondering if this is a good idea, and if it is possible to connect PVC to galvanized pipe...that has no threads? PVC compression fittings (compression x MIPS) seem like a good idea, but those will only work if I have threads. Is there something else I can use?
Thanks,
Tom
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iVe seen them use plastic pipe with a metal cable to pull the pumps weight. lighter and easier.
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This is at the jet pump topside. Not down the well for a submersible. Submersibles usually have one PVC line, the power cable, and a nylon rope for security.
I swapped my jet pump once because the impeller self-destructed. Same HP and all. The brand new jet pump didn't produce anywhere near as much water as the old did. And I couldn't afford converting it to submersible at the time.
So, I realized that my very old cast iron Gould pump was a vastly better unit than the modern plastic ones, and that buying impellers for the Gould is easy.
So, to make a long story short..., I realized that if I had simply gone ahead and pulled the four bolts apart splitting the pump chamber, replaced the impeller, and rebolted it back together, I could have repaired the thing in about 30 minutes for a grand total of $20 in parts.
[I bought a new impeller and a seal for the pump chamber. As it turned out, I didn't need to replace the seal. The old one was still in good condition, and CLR cleaned things up enough so that I could reseal it. If I had replaced the seal, I'd probably have had leaks until it properly seated.]
Instead, I had bought a new pump (for > $200). Installed it, big fight with the lines. Didn't like it. Bought the parts for the old one, put the new impeller in, removed the old pump (big fight with the lines) and reinstalled the old pump (another fight with the lines) - whole process took about a week.
Fortunately HD took the new pump back for a full refund. Return cashier: "it's used!", Guy from plumbing isle: "Well, it didn't do the job, did it? Give him his money back.".
I've learned my lesson. Try replacing the impeller. You shouldn't even have to pull the lines off.
If the motor and seals are good, it's a lot easier to repair the pump in place.
If, when you pull the thing apart, the impeller looks in perfect condition, your problem is that the injector at the bottom of the well is shot. I had that happen - same symptoms as yours.
[When my impeller broke, the motor jammed and stalled.]
One of the cast iron nipples at the bottom had rusted and blown out (and was so heavily rusted into the cast iron injector it couldn't be removed). You can buy _just_ the injector... Doesn't have to be the same make of pump. I replaced the old cast iron one with a plastic injector from a "modern" plastic pump.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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Its not a good idea to hook PVC to unthreaded galvanized piping.
Have you thought about just replacing the motor and rotary assembly since nothing seems to be wrong with the casing?
But there seems to be more wrong that could be wrong. I need a little more info for a better understanding. You say that the impeller is shot from the "ancient motor" but that doesn't really make sense. It could be shot from many different things, but the constant running would cause wear on it for sure. How long has it been constantly running? The low pressure could also be several things, from a bad tank, to a clogged jet.
What kind of pump and motor are on it now?
Gunn wrote:

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snipped-for-privacy@gmail.com wrote:

through the two galvanized pipe very near the pump. The current pipes seem to be flanged to the pump, and the bolts holding the bracket that presses the flange to the motor are -very- rusted. Then, after the pipes are cut, I hope I can get a pipe wrench to remove the straight section to the elbow, and then use threaded PVC into the elbow, back to the pump.
The new pump I just purchased has measurements that are very close to the locations of the current pipes, so it hopefully won't be too bad of a retrofit.
The current pump is a Century. From the looks of it, I'm betting its original...1966. I haven't been able to find any info on that brand, so replacing the impeller is probably a long shot.
The pump is 1/2HP and runs for about 15-20 minutes each time it needs to come on before cyling off. We've lived in the house for 3 years now and that's been the norm. Since it starting on the fritz this past weekend, it would run constantly. Showing 42psi on the pump gauge. We started using the circuit breaker to turn it on/off when we needed it, so we could get by before this weekend when i can replace it. Just purchased a new 1HP so we won't have to hear it run for very long in the house...
Last night, I found directions for the pressure switch (not as old as the pump) lying in the crawl space, and turned the cut-off pressure on the pressure switch down. I think this has made the pump cut off reliably again. Since I have done that, all night and this morning, the pump will kick on, and go off as usual. The pump gauge is now showing about 39psi.
So would that still point to bad impellers in the pump? I'm praying its not the ejector assembly. I have no idea where the well is! The pipes come up from dirt in the crawl space of the house. So I assume they go down under the frost line (21" here) and turn to go outside the house....somewhere. It's not exposed.
Thanks for the responses.
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Century is a moderately well known pump name. It appears to now be part of Magnetek. A company that does well pump servicing will be able to advise you whether parts are still available. This type of pump hasn't changed a lot (except for the plastic ones).

Could.
Or pressure switch has drifted and the pump is just fine.
It could even be that the static well level (related to the water table) has dropped. This _may_ have dropped below the pump's ability to maintain the pressure switch setpoint.
Given the difficulty in fixing the supply lines, it may be best simply to assume that tweaking the pressure switch has solved your problem until the pump more definitively fails.

Probably not. If the system can hold pressure for a while with the pump off and drawing no water, the injector is probably just fine.
If you do have to cut the galvanized pipe, thought should be given to trying to get them rethreaded. Some plumbers should have the equipment. You can often rent it. Or, if you can get the pieces out, you can take them to a plumbing store and get them rethreaded.
Better still would be to take out and replace the cut pieces with plastic. Or at least use some sort of plastic adapter between the galvanized and the pump.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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Chris Lewis wrote:

And on makeing the PVC - IRON connection, use a male PVC fitting into a female galv. The female PVC to iron adapters tend to split on the parting line (yes, I found that out the hard way in the middle of winter with the fitting buried 4 ft deep).
Harry K
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Chris, Larry, thanks for the comments. The well pump is holding up well so far since that pressure switch adjustment. Being that it is only a max. of about 70ft. deep or so, and we are having a very, very dry summer in southern Maryland, the water table dropping scenario is quite possible.
Glad to hear that the ejector is probably working fine. I didn't know anything about this pumps until the last couple of days. I still need to learn more about how these parts work together...
If I can cut the old pipe and get the remnant unscrewed from the elbow, that elbow is a female, so I have already purchased 1" and 1-1/4" male PVC adapters as replacement.
Well, the pump just shut off. :) So, I may delay my surgery to get a more definitive answer, as Chris mentioned.
You guys have been a huge help, thanks so far!
Tom
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