Pump gradually building to lower and lower max pressure.


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Old 05-23-16, 10:12 AM
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Pump gradually building to lower and lower max pressure.

I bought an old farm house from a foreclosure, and have been having problems with the water. Because of the situation with buying it, I don't know when the well was drilled or how old the pump is. But I do know it is about 30 feet deep, and has a deep well jet pump. The pump is 3/4hp and a 115/230 model. It is wired to 110v, and I double checked the switch is definitely set to 115v.

When we first got here, the pump couldn't get any water into the tank at all. We got a plumber to come, he said the foot valve must be clogged, dug up the well and pulled it out, blew into it a bit, and put it back. To prime it, he shook the pipes up and down which kicked up a ton of dirt into the water. That still didn't work, so he tried pulling it out and blowing it again, noticing that the cage had been knocked off the foot valve (I assume from him jerking it up and down to prime it). This time it "worked" and the pump was able to get water into the tank, but he had to turn the pressure cut off way down.

Now a month later, the pump is no longer able to get up to the cut off pressure. Is this likely just dirt in the valve again? And is it from him kicking up a bunch of dirt when he primed it? Or is it possible that the pump is failing slowly and just can't build enough pressure? Is it worth buying a new pump and swapping it out in case that is the problem, or do pumps not really fail gradually like that?
 
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Old 05-23-16, 09:16 PM
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I hate to say this but it sounds like your plumber didn't really know what he was doing.

I'm guessing this is a single pipe well system ?
A single pipe jet pump will have a hard time priming at 30'. The typical limit is 25'.

The check valve's job is to allow water into the pipe when the pump creates suction. When the pump stops the valve needs to close to keep the water in the pipe so that when the pump restarts it draws water in and not air.

Two things happen when the check valve is bad. The first thing is that when the pump shuts off the system pressure drops to zero. (provided there is nothing using water)
The second thing is the pump will not pick up a prime.

When you prime a jet pump you need a way to pour water into the line that goes to the well and fill it with water. Obviously this will not work if the check valve is bad.

I have never heard of shaking the pipe to prime it.

If your pump is still priming by itself then it would appear that the foot valve is working properly.

In your case it sounds like the pump is bad. It sounds like the impeller may be severally worn most likely from the highly abrasive dirt content of the water.

You may be facing drilling a new well if the dirt content is that high in your shallow well.
 
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Old 05-24-16, 04:01 AM
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Originally Posted by PJmax
I'm guessing this is a single pipe well system ?
A single pipe jet pump will have a hard time priming at 30'. The typical limit is 25'.
No, it is a deep well jet pump. Two pipes, foot valve/impeller down in the well.

Originally Posted by PJmax
If your pump is still priming by itself then it would appear that the foot valve is working properly.
It doesn't prime by itself, it maintains the prime it was given. Which means the check valve is not broken and letting water flow back. It can still be clogged though, letting not enough water through the correct direction when the pump runs. But if the dirt clogged it, it would have been a problem a month ago when he kicked up all the dirt right? Is it likely for dirt to be in there but out of the way enough, and then over time shift a little and start clogging it again?

Originally Posted by PJmax
In your case it sounds like the pump is bad. It sounds like the impeller may be severally worn most likely from the highly abrasive dirt content of the water.

You may be facing drilling a new well if the dirt content is that high in your shallow well.
The dirt was only from him yanking the pipes up and down, it settled out after an hour. Is it common for a pump to fail gradually this way, pushing less and less hard over time? I'm not sure if I can find a store selling a pump that I can swap in and still be able to return if that wasn't the problem.
 
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Old 05-24-16, 05:34 AM
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Deep well jet pumps have a venturi at the bottom that has some tiny passages. They are quite susceptible to being clogged.

I had a similar situation to yours on an irrigation system so it would sit 6-9 months without being used. Every summer I had the same headache of the venturi down at the foot valve clogging. If it's mild you'll get water but never up to full pressure and at worst it won't even get the water up and out of the well. Mine was usually clogged with flakes of rust I believe from the inside of the pump housing. Sitting long periods allowed rust to develop then when the pump is finally used bits break off and circulate until they get caught at the venturi. Eventually I could get all the bits out and it would work flawlessly after that but startup every summer was a half day process that required pulling the foot valve repeatedly to remove the clogs.
 
 

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