Jet pump question.

[ponytug]

Sure, run the extension cord over, drop the intake hose(s) in the well, and you are good to go. You can block off a centrifugal pump, but don't do it for very long as they can and will overheat. We did something similar for a decade or so to water the the garden, dropping the intake in, connecting the garden hose to the pump, and then plugging in the pump.

I didn't realize that you had the pump. If you don't, you only need the jet pump if the water level is more than 20' or so down, at which point, I would buy the submersible, rather than buying a jet pump... I would make sure that the extension cord connections are protected from water...

All the best,

Peter

 

[3Ts]

The answer to your question as to whether a jet pump outlet can be plugged is "yes, but with a condition". The water in the pump housing is not going anywhere and you're putting energy into it so it will heat up. As long as you don't overheat the pump you'll be fine. I think 20 to 30 minutes is quite a long time but it depends on the ambient temperature and the rating of the pump. A jet pump is a centrifugal pump with a venturi. A centrifugal pump has a disk that rotates to pump the water, if water is not moving, there is no damage to the pump. The venturi has no moving parts.

I used a 3hp centrifugal (not a jet since it did not have the venturi) pump to draw out of a pond for my irrigation system. It ran and I got whatever psi & gpm it would put out for the sprinklers. I did plan the sprinkler layout based on the expected pump flow & psi so there would not be much deadheading.

Here's a link that you may find useful. Jet Pump

 

[Egon]

Put a pressure relief valve between the pump and shut off valve.

easiest is a pressure shutoff. No need for a tank.

 

[CobyRupert]

I think you’re asking if a pump can dead-head without damage. I think there are a couple issues.
Pressure will rise, can the closed off system tolerate this pressure? Maybe experiment and put a pressure gauge to see what that dead head pressure is.
The other issue, as people have mentioned, is will heat rise at the pump? If it’s fan cooled, maybe not. It may be that the pump runs at less power/amps when it is deadheading and NOT working hard to lift pounds of water. One should also note that frequent starting and stopping of a motor (with inrush) may heat a motor more than running a motor. We tend to size motor cables, starters and breakers based on the full load amps of a CONTINUOUS DUTY motor that runs, yet a motor manufacturers have allowable starting intervals and the Electric Codes are different for motors with intermittent duty.
I’m pretty sure there are products that reduce the flow so that the motor runs more continuously. Perhaps a salesmen will chime in and provide more details.

 

[Valveman]

No, you should not completely block flow from a jet pump or any pump. With a jet pump the water will start getting hot in just a couple minutes. Any longer with no flow and damage will occur. You also cannot use a pressure relief valve with a jet pump as a jet pump only builds 50-60 PSI and works at that pressure. A 70-75 PSI relief valve would do no good and the pump will still get hot. The motor is fan cooled and won't get hurt, but the pump is cooled by the flow it is moving, and needs at least 2/10's of a GPM flow to stay cool.

If you have 4" or larger casing, I agree a submersible would be better, and it will work with a pressure relief valve as they build much more pressure than a jet pump.

 

[steve tym]

If the pump is moving water, it's happy. If the pump is running and not moving any water, it will self destruct.

 

[etpm]

No, you should not completely block flow from a jet pump or any pump. With a jet pump the water will start getting hot in just a couple minutes. Any longer with no flow and damage will occur. You also cannot use a pressure relief valve with a jet pump as a jet pump only builds 50-60 PSI and works at that pressure. A 70-75 PSI relief valve would do no good and the pump will still get hot. The motor is fan cooled and won't get hurt, but the pump is cooled by the flow it is moving, and needs at least 2/10's of a GPM flow to stay cool.

If you have 4" or larger casing, I agree a submersible would be better, and it will work with a pressure relief valve as they build much more pressure than a jet pump.

The well is 21 feet deep and 3 feet in diameter. I was thinking that if the flow cannot be blocked for any significant period of time then a relief valve would work. But you say I cannot use one because the jet pump only builds 50-60 PSI. Why cannot I use an adjustable relief valve that opens at, say, 40 PSI. Then watering with a hose, which is what we will be doing, will keep the valve from opening, but when watering stops the valve will open and dump the water back into the well. I don't know where to buy one of these relief valves if they exist but I'm thinking they must. If I do buy a submersible can I use a pressure relief valve that just dumps the water back into the well? I really want to avoid the use of a tank and pressure switch because if I do then the whole business starts to get pretty expensive. I would need a tank, switch, CSV, and pump. Just for running one hose.
Thanks,
Eric

 

[etpm]

Looking online I found a submersible pump made by Vevor that fits the bill for my use. It will go to 79 PSI so I could use a 70 PSI relief valve that just dumps the water back into the well. Submersible pumps are way better than jet pumps efficiency wise. I also like the idea of having no pump on the surface and so not having to worry about priming a pump. I could use a small tank and pressure switch I suppose but I would rather just have the pump run continuously when I'm watering, turn it off with a switch and then unplug it because the pump will be powered by an extension cord for the foreseeable future. BTW, the word "foreseeable" just looks wrong. Like there is an extra e.
Eric

 

[ponytug]

I would just add an inline pressure switch. They are inexpensive, and will simply turn the pump off when the hose kinks or someone shuts a hose nozzle.

All the best, Peter

 

[etpm]

I would just add an inline pressure switch. They are inexpensive, and will simply turn the pump off when the hose kinks or someone shuts a hose nozzle.

All the best, Peter

I'm hoping to find a pressure relief valve that dumps the water back into the well whenever the hose is shut off. The well is for sure not potable because it is surface water. Because of this when done using this well for watering the pump will be unplugged. We could, I suppose, try to seal off the top of the well so that not even a bug could make it past the seal, but that won't do anything about the surface water that fills the well. And I have no idea what kind of bacteria there could be in the surface water. We have lots of deer and deer poop can carry the type of e-coli that makes humans very sick. And deer for sure poop near this well.
Even though the top two feet of the well is a square concrete construction the remainder is just a 3 to 4 foot diameter hole in the ground. As the ground water level changes so does the well. During the time of the year when the ground water is highest the water in the well is about two feet from the ground surface. When the ground water is at its lowest level the well water surface is about 18 feet below the ground surface. It's interesting to watch the level change because it lags the rains. So the water level continues to drop after the rains have stopped and then when the rain starts again it rises a few days after a big rain.
Eric