Why would well pump cycle on and off every second?

I have a 40-60psi shallow well pump with an air bladder water tank. The
pump is in the well house and the tank is in the home 75 feet away.
This is a new well. My problem is that the pressure switch trips or
cycles on off on off on off every second when the pressure reaches
40psi. I noticed when the pump is kicking on and off every second, the
pressure gauge is jumping from 40 to 50 to 40 to 50. I don't think my
pressure tank has anything to do with it because the water at a faucet
is able to run along time between 60psi and 40psi, before the pump
kicks on at 40psi and starts doing it on off on off dance. Any ideas
what the problem might be? Thanks
Reply to
nomad
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Is there a check valve downstream of the pump to keep it primed?
Is there an arrow on the valve? The arrow should be pointing AWAY from the well and TOWARD the house.
If you can't tell from the markings take the valve out to determine if it is in backwards.
The pressure should take longer than a second or two to go from 40 to 50 psi, assuming you have an ordinary 3/4 hp pump system.
Bret Cahill
Reply to
Bret Cahill
Your air bladder has failed (collapsed) or has never been filled with air. Probably the latter if its always done this. There should be a fill valve on the top of the tank. Compressing the air in the bladder is what allows the system to store energy. Without an air reservoir the pump will build pressure almost instantly and the pressure will drop with only a very slight amount of water removed from the system. So you also must have a tiny leak.
-jim
Reply to
jim
Something doesn't compute here. You say the pump kicks on and off between 40-50 but the tank has 60 psi. Where is it getting the pressure?
In any case if it is a new well, call the installers. Something is seriously out of whack and it should be under warranty. Could be problme with the pump controller, wrong pre-charge, blown bladder or just plain gremlins.
Harry K
Reply to
Harry K
Of course, if the bladder on the pressure tank is kaput, or the air charge has leaked down to let the whole thing fill with water, or you've got a broken line, or simliar, the pump is going to cycle madly trying to maintain pressure - It comes on. Pressure is good. It shuts off, pressure falls immediately since it isn't pumping. It comes back on to bring it back up. It gets there. It shuts down. Pressure gone... lather, rinse, repeat until the pump motor burns up.
Then again, re-reading the original post, the start/stop pressures might be a bit too close together - If you want the pump to come on at 40 PSI, it's not unusual to set the "off" pressure up around 50 or 55, specifically to give the pump time to rest. Sounds as if either your switch is gone, or it's set with the "off" pressure too close to the "on" pressure.
Reply to
Don Bruder
The backwards check valve turns the system into a hydraulic ram. Each time the pump starts the check valve slams shut. The pressure reaches 200 + psi upstream of the valve for an instant which causes the pressure switch to shut down the pump.
An instant later the pressure drops and the pump starts again.
The new well pump was installed by a new well pump installer who didn't look at the check valve and didn't wonder much about the short pumping cycle when he tried it out.
Either that or this is a troll, a _Car Talk_ puzzler.
Bret Cahill
Reply to
Bret Cahill
The system is simple... But reality might add complexity.
If I understand you correctly, your system is supposed to turn the pump on (cut-in) at 40psi, and off (cut-out) at 60psi.
Does it have any kind of low-water detection? Perhaps your well is going dry, so the pump turns on, water gets low, pump turns off. Pressure switch still calls for water, so pump turns on, water gets low, and etc.
How does the pressure get up to 60psi so you can test the faucet, if the pump keeps going on/off at 40psi?
You say the system is new... Did it ever work properly?
Where is the pump relative to the pressure switch and to the air tank and to the pressure guage? If there is a restriction in the plumbing between the pump and the tank, even something so simple as a long pipe slightly undersized, and the pressure switch is on the pump side of that restriction, the pressure when the pump turns on will go high because of that restriction. Then the pressure switch will turn off the pump, and pressure will equalize on both sides of the restriction. If the equalized pressure is below the cut-in, the pressure switch will turn on the pump again, pressure will rapidly build, and etc.
sdb
Reply to
Sylvan Butler
The most likely cause is that the preload pressure in the reservoir is 40 and the pump pressure switch cuts on just below this. I would try increasing the pressure switches on setting to say 50 psi, or alternatively decreasing the reservoir's preload pressure to say 30 psi. That gives more hysterisis between pump on, and pump off
Worth a shot, anyway
Brian Whatcott Altus OK
Reply to
Brian Whatcott
1) Is there an appreciable elevation difference between the pump and the house?
2) Is there a reason for not having the bladder tank next to the pump?
3) Do you have a way to bleed air from the lines? (air in the lines will really screw things up)
I built and used a pumped system with a purification system for nearly 20 years and by the time I hooked up to a municipal water system I had it fine tuned. My wife pleaded "please don't die cause I'd never be able to explain how this thing works". I had a wild assortment of pipes & valves & bypasses and had totally eliminated the bladder tank - but it delivered full pressure with no annoying cycling. I also had a 50' rise from the pump head to contend with - backpressure can be your friend.
Repeated cycling is hard on the pump and will eat up the pressure switch contacts in no time.
AL
Reply to
AL
I see I have raised many questions by not giving enough information. I installed the well pump sytem so it is my fault that the thing is not working. No installer to blame.
There is a foot valve with a built in check valve on the end of the 1 1/4" line going down into the well, so there is no way to get it on backwards.
The pressure switch is mounted to the side of the shallow well jet pump.
The well has plenty of water in it.
I tried replacing the pressure switch with a new one but I still had the same problem.
Pressure tank is fine. I filled the air bladder to 38 psi prior to starting the 40-60psi pump.
I am able to get the system up to 60psi by holding the pressure switch contacts closed for the first few seconds of cut-in at 40psi, when the contacts are jumping open and closed over and over again.
There is a 1 1/4" line running 75' from the pump to the house exterior wall. The last 10 feet or so of line from the exterior house wall to the pressure tank is 1" line, which is probably my problem. I bet I made the mistake of utilizing some of the interior piping and spiced the pressure tank into too small of pipe, as Sylvan Butler mentioned. I probably should try running the last 10' of line to the pressure tank with 1 1/4" line. The inlet opening into the pressure tank is 1", so I figured it would be ok to spice the pressure tank into a 1" line. Maybe it needs to have 1 1/4" line all the way up to the 1" pressure tank inlet opening. I guess I find out if that is the problem. If not, I'm sure if I moved the pressure tank into the well house with the pump, it would solve my problem. But seeing I live with cold winters, I rather have the tank inside the house.
Reply to
nomad
Dear nomad:
Connect this to the reservoir. At worst, tee it off the outlet.
I'm thinking this is a little high (38 psi), if the purpose is to minimize cycling. But you also don't want scuffing inside the tank. If this is what the instructions said to do, OK. But I'd run closer to 30 psig.
No, just move the pressure switch. The jet pump is pressurizing this column of water, and before the inertia can "give way" the pressure switch has shut off the pump.
No real need to do this, unless you have OCD (obsessive compulsive disorder), or extra pipe and time.
Moving the switch will do the trick. You may want to put a dedicated purpose contactor in the well house, and simply have the pressure switch turn on and off the coil voltage that energizes the contactor. That way you don't have high current running long distances.
David A. Smith
Reply to
N:dlzc D:aol T:com (dlzc)
< No, just move the pressure switch.
This may not be very easy. Moreover, if a check valve between the tank and the pump is backwards, the pump won't have any water flow for cooling.
The current situation more or less works.
< The jet pump is pressurizing this column of water, and before
< the inertia can "give way" the pressure switch has shut off the
< pump.
First look for any backwards check valves between the tank and the pump.
And how big is this pump?
Bret Cahill
Reply to
Bret Cahill
Nope. Can't be a backward check valve or he would get no water at all. In any case, in a proper installation there should be no checkvalve after the pump.
Harry K
Reply to
Harry K
Dear Bret Cahill:
Move the tank, or move the pressure switch. "Easy" isn't what he was looking for.
He did indicate that the only valve he put in was a non-reversible foot valve, and that if he holds the contact closed he gets the pressure up to 60 psig. Your imagined problem apparently isn't there.
No, it doesn't. He gets about 40 psi in the tank, and a burned out motor.
He installed the system. He didn't note anything except pipe sizes and a foot valve.
Jet pumps are like short-winded horses. They can briefly generate lots of flow and pressure, apparently more than the nameplate rating, due to the high rpm. Note that his cycle is about 1 second...
David A. Smith
Reply to
N:dlzc D:aol T:com (dlzc)
Dear Harry K:
There are check valves used after pumps in dual (redundant) pump systems. Also, since a pump is free flow in reverse, how is the pressure maintained in the tank with the pump off? You are being a little over general...
David A. Smith
Reply to
N:dlzc D:aol T:com (dlzc)
I agree your diagnosis is correct. It has nothing to do with a check valve. The pressure switch is simply measuring the pump output not the system pressure which is where its supposed to measure the pressure. Moving the Tank probably makes more sense unless the power is coming from the house anyway. If changing the pressure switch means putting it on one end of the power feed instead of the other that will work fine. If changing the pressure switch means running an additional 75' of wire to feed the power it probably is best to move the tank (although a remote control circuit would work also). If there is enough room in the pump house and if the problem of freezing has already been solved for the piping and pump then the problem of the tank freezing doesn't seem like it would be difficult to solve.
-jim
Reply to
jim
Not hardly. We are discussing a single home well system. There is no need for a checkvalve between the pump and the tank. A reversed one is -impossible- as no water at all would pass it. As to the pump running backward. It is prevented by the footvalve which is a checkvalve but it is -before- the pump.
Harry K
Reply to
Harry K
The proper pre-charge is about 2 psi below the cut-in. That will be stated in the literature with his tank. Any deviation from that setting only makes the pump cycle more often than it should.
Harry K
Reply to
Harry K
If I was to move the pressure switch from the well to the house, I would have to trench and run 75' of power cord. Although, It is almost a toss up as to which would be worse, moving the tank or moving the pressure switch and running a new power cord. I think I might try reducing the air pressure in the tank bladder to 29psi and try running the pump from 30psi on (cut-in) to 60psi off (cut-off) and see if that gives the pump enough difference between on and off pressures to keep it from kicking off as soon as the pump kicks in.
Reply to
nomad
One other thing to try would be to put flow restrictor and snubber at the pressure switch to limit the spike in pressure. (A valve and a short length of vertical pipe to act as an accumulator) _ | | | | | | | | ______ | | snubber | PS | | | |____| | | | |_| |______| | | X-| valve ______|____________________
Reply to
jeff

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