Why would well pump cycle on and off every second?

I think that a pressure wave hitting your pressure switch is likely your problem. (as has been noted)

If it were me, I'd stick a snubber (a vertical bit of capped off pipe full of air) on a T with the pressure switch, and a smallish orifice between the T and the rest of the system. This would give a damping effect to the pressure wave that the switch sees coming from the pump on startup.

If you size the orifice too small, or the snubber too big, you could see excessively high pressures in your system (the pressure switch doesn't see the actual high system pressure soon enough to turn off the pump), so perhaps there's a bit of math out there someplace as to how to do this safely?

My guess is that the hole could be pretty large, and the snubber pretty short and still solve your problem though...

Al...

It seems that pressure is being lost very much to fast.

If the sensor is down stream of the check vale... then falling pressure could be due to a fault in the blader tank, water filling the air space.

Most likley... the check valve is not working, and water is leaking back through it as soon as the pump is turned off.

Is the water filtered before it gets to the check valve ? Strip the valve down and look for... cloth, string, a bolt... a broken spring, a missing seal.. :-)

You mean the manufacturer actually tells you how to avoid short-cycling? Well, how about that!

Brian W

That may help. You might also consider just getting another small bladder tank for the pumphouse. That would be even better than the standpipe that others have suggested.

-jim

Dear nomad:

It won't. Likely the "kick off" occurs simply in accelerating the flow between the pump and the tank inlet.

If you like to play with electrons, you could drive a time-off-delay relay with the pressure switch, and use the relay (through a contactor) to power the pump. This would give you a "variable orifice plate or accumulator" effect that could be dialed in to meet the need.

David A. Smith

Dear Anthony:

You are a genius! I'd figure more like 2 sec or less, though...

David A. Smith

Sounds like it will work. Definitely worth a try and beats having a tank subject to freezing.

Harry K

Nothing new to add but I thought I would wrap up all the good suggestions in one batch. Lots of good brainstorming in this thread.

Cause: Looks like the 75 ft run is causing the pressure switch to see overpressures at start-up. That could be due to two things:

1. Just the physical restriction getting the colume of water moving: Most likely. Your saying that you can force the pump to stay on by holding the contacts closed "for a few seconds" is the clue.
2. A restriction in the pipeing somewhere. The size pipe you have should not be enough to cause it. If you have a water filter/conditioner, it could be partly plugged. That is one common cause of restrictions but I don't think it is in your case.

Cures:

1. Move the tank: I wouldn't. Running a trench and wire for 75 ft is not that much work and you won't have the nuisance of having to keep the tank from freezing or maintaining it in a hole in the ground.

1. Move the pressure switch to the tank - I would. Again adding whatever wiring is needed for 75 ft is not that much work. It also moves a maintenance item to an easily accessable location (the basement).

2. Add a delay timer: Good but adds another thing to the system that can fail.

Your plan of changing the cut-in pressure to 30 will probably fail. The problem is not the differential between cut-in/cut-out. The problem is that the pressure switch is seeing pressures at or above 60 psi at start-up. The switch will still see overpressure.

Harry K

That will work if the extra pressure the switch 'sees' at start up is between 20 and 30 pounds. Your cures didn't include adding an air filled stand pipe in the pump house. Nomad can simply put a stand pipe filled with air where his pressure switch is now located and put the pressure switch at the top of the stand pipe. Having a column of air between the water pressure and the switch should help a lot. He may need some kind of reservoir of air in the pump house anyway (another small bladder tank would be the most reliable) as he may also be getting a 'hammer' when the pump shuts off.

-jim

Dear Harry K:

Just a little kibitzing...

"Mutually exclusive cures". Don't try and implement all of them. If you do 1 or 2, you don't need 3.

The pressure switch need not switch the entire pump power. It can take 115/230 vac from a wall socket, and direct a half-amp or so to power the contactor near the pump. So you don't need more than one run of small sized "Romex".

"nomad", if you implement #1, you'd still likely need to move the pressure switch to the tank. If you implement #2, you'll need the suitable for being buried wiring, a power cord for pressure switch power, and a dedicated purpose contactor (you can look this up at

If you implement #3, you'll need a time off delay timer, a socket for it, a power cord the timer, and the dedicated purpose contactor. The dedicated purpose contactor will last far longer than the pressure switch contacts, if that is any consolation. If you need more detail, let us know.

David A. Smith

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The system pressure starts at 40 and hits 60 when the pump is activated if it starts at 30 it may not reach a peak of 60.

Putting an air reservoir in the pump house is the right way. Moving the sensor to the house will solve the immediate problem, but the pressure spikes when the pump kicks on an off will stress the piping system and pump and will lead to shorter life span.

-jim

IMHE, the bladder is pressurized too high for efficiency, AND too close to shut-off. The air bladder should be lower than the low switch setting.

I would first set the bladder charge to 25 psi.

Next, since if the pump is not securely mounted and the switch is on the pump, the switch will move as the pump moves and the pump motion then moves the switch back. I would move the switch/secure the pump and the pump stand.

If one of these does not work, you might need a 90 degree turn in the water line just before the securely mounted switch, but not a 90 turn supported by the switch.

one of those should do it.

-------------------------

background---

1) - as incompressible water fills the accumulator tank with a bladder charged to 20 psi, the compressible air will stay at 20 psi until the water pressure rises above 20 psi. At that point, any higher pressure further compresses the air and squeezes the bladder, which fills the part of the tank vacated (by the compressing of part of the bladder) with water. Thus, when the water is at 60 psi, the air in the bladder is 60 psi and the tank has more water and small bladder. At 50 water psi, 50 air psi and less water in the tank and a larger bladder - and at 40, 40 and even less water -or in your case, no water, just air. That is, as the water is drained for use, the air pressure provides the force to expand the bladder and empty the tank, from 60 psi down to the pump lower setting

2) the switch uses a spring to sense pressure. In your case, one spring is set at 40 psi.

3) the bladder is a spring. In your case, the air spring is set at 40 psi initially

4) the water has mass, and it has momentum which will be felt as a force on anything in its way on along run. Like water dynamics being misread as static pressure.

5) a switch is a part with mass - if you move it as it is closing a circuit, that mass may move and open the circuit again. Rule of thumb is to not mount sensitive switches to parts they control.

Basically, #1 - if you have the bladder pressure set at the lower setting, the switch vibrates as part of a spring-mass-spring rigid-water-mass/pump with the switch spring set at 40 psi fighting the 40 psi air spring of the bladder. Setting the bladder to 25 psi should cure that.

As to #2 - If the cycling is because you have long run straight at the switch, you might be able to stop the cycling by adding a turn in the line to stop the running-watermass from hitting the switch spring. Of course, putting that 90 on the switch won't help, because the water-hammer force will go right into the switch again.

As to # 3 - If the cycling motor start is caused by switch moving its contact to closed which then moves, and puts the switch contact back to open as motor twists - move it off the motor ( or, if you don't have to drain it and thus have freezing to worry about that will shrink the pump more than the mount, secure the motor more rigidly.)

(note that your switch and gauges even when used carefully are likely no closer than 5% accuracy, so 40 can be 38-42, and your 38 can be 36-40, an overlap)

Not if the pump is set to come at at 40. Tank precharge should be approximately 2psi below pump cut-in pressure.

Complete nonsense. As water enters the tank, the volume of air decreases, and its pressure necessarily increases immediately. If the pump isn't developing more than 20psi, _no_ water will enter the tank whatsoever. If the pump is developing more than 20psi, water begins to enter the tank immediately, and the air pressure also begins to increase immediately.

[snip]

More nonsense. After the initial fill, as water is withdrawn from the tank, the pump will kick on when the pressure drops to the cut-in setting of the switch (40psi in this case), regardless of whether the precharge pressure was

25psi or 38 as it should be. The only difference is that, at the moment the pump kicks on at 40psi, there will be more water in the tank if it was precharged to 25psi than if it was precharged to 38. Either way, the pump comes on at 40 and shuts off at 60. The precharge pressure does *not* affect that.

Alan, I picked up a little 2 gallon pressure tank for $20 and mounted it right on the pump, kinda like you recommended. It took care of the inital surge of pressure and cured my problem. Now when the pump kicks on at 40psi, the pressure doesn't jump up at all. Before the pressure would jump up 20+ pounds causing the on off on off pressure switch problem. The air chamber / snubber cured it completely.

Before trying the snubber, I changed out the 1" pipe I had on the end of the line going to my pressure tank with 1 1/4" pipe. That didn't make any difference.

Dear nomad:

Be prepared to bleed water out/force air into the tank. Over time this air precharge will bleed off. Additonally, since this tank is not kept wetted, there will be corrosion at the air-water interface (assuming either steel or stainless steel tank).

You applied a bandaid, and one that will "become infected" if not replaced. A timer will work, as will moving the pressure switch or the tank.

It is your house, your budget, and your time. You get to choose when and how you spend it.

Good luck!

David A. Smith

No he cured the problem your solutions would only mask the problem which is the the pressure surge on start and stop of the pump. If the 20 gallon tank is designed for what he's using it for (i.e. has a rubber bladder inside) none of your dire predictions apply.

Yeah, don't listen to this guy.

-jim