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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
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WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PUMP REPAIR GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMP SHORT CYCLING
WATER SOFTENERS & CONDITIONERS
WATER TANK REPAIR PROCEDURES
WATER TANK: USES, TROUBLESHOOTING
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL CHLORINATION & DISINFECTION
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
Causes of & cures for water pump short cycling on and off:
This article explains how to diagnose all of the various causes of well pump short cycling - what causes the well pump to run too often or to turn on and off too rapidly.
By understanding the cause of too-frequent water pump on/off cycling we also point to the necessary repair.
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Common Causes of Well Pump Short Cycling: how to diagnose & fix well pumps turning on and off too often
Short cycling of a water pump which is defined at SHORT CYCLING WATER PUMP means that the water pump or "well pump" turns on and off too rapidly or too frequently when water is being run in the building.
If this is the problem with your water pump, this article (below) describes the most common causes of this problem.
The most-common cause of pump short-cycling is loss of air in the water pressure tank.
This is the topic discussed at length below, and corrective steps are detailed. However there could be other, less common plumbing problems that cause this symptom. Before "fixing" a problem it's useful to identify the correct problem, less we waste time, effort, and money.
This article describes the most likely water pump short cycle causes include the following, listed more or less in the order of probability:
Our complete diagnostic list of all known causes, diagnostic steps, and repair procedures for well pump short cycling is at SHORT CYCLING DIAGNOSIS TABLE
Loss of sufficient air charge in the water tank is perhaps the most common cause of water pump short cycling, and is a particularly common problem with older non-bladder type water pressure tanks or with newer bladder type water tanks if the bladder has become damaged.
The remedy for a water tank that has lost its air charge is pretty easy and is discussed in great detail below at
A defective water pressure control switch. Switch contacts can burn-up, or the opening into the switch
which senses the water pressure in the system can become clogged with sediment or debris. This usually
shows up as failure of the pump switch to turn on or off at all, rather than short cycling. But the switch could be damaged or improperly adjusted, causing "short water pump cycling."
The small diameter of this tubing and still smaller diameter of the pump switch orifice makes clogging easy if your well water is high in sediment or minerals.
On rare occasions we can tap on the well pump control switch and it will begin working again, but not for long, and not reliably. Another water pressure control switch failure is the rupture of a rubber disk or "bladder" inside the switch itself. If you detect or suspect a defective pressure control switch, try replacing it with a new one.
We see a similar problem affecting water pressure gauges on private water systems: debris or mineral deposits can clog the pressure sensing orifice on the water pressure gauge, causing it to fail to respond at all, or to respond inaccurately to changes in water pressure.
When we find a clogged water pump pressure switch or the tubing connected to it, or a clogged water pressure gauge, we replace those items. A well pump pressure gauge that does not respond to pressure changes is potentially unsafe as it could lead to excessive pressurization of the water tank and building piping.
A blockage in the water supply piping. For example, a clogged or nearly-clogged water filter can cause the pump control to cycle on and off rapidly. This is because the blockage causes water pressure (between the pump and the filter) to rise very rapidly when the pump turns on. The author once replaced a pump control switch only to discover that the real problem was a clogged filter, so check this item if you have filter(s) installed on the system.
A clogged water filter can block water flow between a pump and water tank or between a water tank and the rest of the building.
Try changing the water filter by installing a new cartridge; temporary diagnosis can be
made by simply removing a suspect water filter cartridge from its canister entirely. I've also seen a clogged
water filter cause water pump short cycling, with a rapid "on-off" pump cycle (which is bad for the pump and
pump relay switch.)
Too much air in the water pressure tank - overcharging: If a well pump pressure control switch is set to cut on at 30 psi and off
at 50 psi, at the cutoff point the water tank is empty (a bladder type captive air tank) or nearly empty (a traditional water tank)
of water, and the air pressure in the tank is about at 30 psi.
A defective or ruptured captive-air water tank bladder: it sounded so weird we didn't believe it at first, but one reader explained that the water-containing bladder in their WellXTrol™ type water tank had collapsed and become stuck on itself.
The effect of a water tank air bladder that has collapsed and adhered to itself was that the water pressure tank would accept only a very small volume of water before the stuck-up bladder would reach the pump shut-off pressure. The bladder was replaced and things got back to normal.
If your water pressure tank has a ruptured or torn or leaky bladder that can cause short cycling of the water pump. You might "get by" temporarily by forcing air into the water tank - sometimes this works until you can get a new bladder installed or until you install a new water tank entirely.
But sometimes adding air to the water tank with a torn or ruptured bladder won't work - that suggests that the bladder has become adhered to itself inside the water tank.
Reader Comment: frozen water pressure tank traced to cause of well pump short cycling
Your site was very helpful for information on "short cycling" of a water well pressure sensor switch and pump relay. However, none of the listed causes matched my issue, so I wanted to relate what I discovered.
After a very cold night (approx -25F), we had some freeze-up and ruptured pipes in the system. I thawed everything and replaced the broken pieces, but the well pump was short cycling, clicking on and off.
I knew there had to be an obstruction in the supply line leading to the pressure switch, but I had thawed the line thoroughly. In a moment of insight, I realized that there might be ice in the pressure tank itself, so I shined a halogen work light on it for a few hours, and that solved the problem. Thanks again for the information your site provides. It really helped. - E.T. 12/18/2013
Reply: consider some freeze-proofing steps to prevent recurrence of a frozen water tank & piping
While it is common for water supply pipes to freeze at one or more cold spots in a home during very cold weather, it is more unusual for a water pressure tank itself to freeze up - though I could imagine that if pipes are frozen around the pressure tank, the pressure tank outlet tee itself might also freeze solid - causing well pump short cycling.
If your freeze-up occurred because the whole building lost heat for a time during very cold weather I can understand a more broad range of frozen plumbing pipes, valves, tees, and even a pressure tank or toilet tank (which sometimes will also burst when frozen).
If the freeze-up of the pressure tank that you cite occurred when your home had not acutally lost heat, I'd look at some freeze-protection steps to prevent a recurrence. The first choice is finding and sealing drafts, next adding insulation, and third, in some difficult spots adding a heat source. We have seen successful freeze protection in well pits with just the addition of the small amount of heat provided by a 75W incandescent light bulb hung close to the piping and pressure tank.
See Older steel Tanks for photos and text describing how this happens and how you might spot an intermittent air leak from a faulty water storage tank.
Be sure to see our separate diagnostic guide Table to well pump short cycling in table form at SHORT CYCLING DIAGNOSIS TABLE.
If there is a hole in the well piping anywhere between the bottom of the well and the water tank itself, water squirting out of this hole during every pump-on cycle tends to enlarge the hole over time. When the water loss at this leak is great enough, the well pump has to run longer to reach the pump control cut-off pressure, and at the same time, water running back out through this same hole drains pressure and water from the system, causing the pump to have to run more often.
If the leak in the well pipe is below the water level inside the well you will still have water and water pressure loss back through the leak when the pump stops, but you probably won't find air entering the well piping.
Watch out: If the well piping leak is severe enough the well pump may run continuously - a problem you'll notice quickly if the well pump is inside the building. But if the pump is an in-well submersible unit, it may be running continuously without anyone noticing it - until the pump fails.
Bad water pressure tank location: Locating the water pressure tank too far from or on a different level from the pressure control switch can cause pressure control switch bouncing and rapid water pump on-off cycling at the start or end of a water pump operating cycle. See Where to Locate the Replacement Water Pressure Tank
Water-logged internal-bladder type pressure tank with a pinhole leak in the bladder may cause pump short cycling but may not squirt water at the pressure tank air valve.
Ask your plumber, as this expert may know other causes and remedies that we have not identified in this article series.
Short cycling of a water pump (which is discussed in this article) means that the water pump turns on and off too rapidly or too frequently when water is being run in the building. We also provide a complete
If you are not sure what "water pump short cycling" means or how it is recognized, see
Intermittent water pump cycling which is discussed at
Loss of water pressure means that the pressure with which water enters a plumbing fixture has become too slow, or is sometimes too slow or weak in water flow rate, or water flow may stop entirely. See WATER PRESSURE LOSS DIAGNOSIS & REPAIR
Improper pressure tank draining & re-fill might also cause pump short cycling following a water or plumbing or water tank repair attempt.
Reader M.L. offered these comments [ edited for clarity and brevity]
I've searched your site for reasons why pressure is lost in a system if, during a power failure, a fixture is used somewhere in the house; in my case, a toilet.
I came across it being mentioned on one of your pages, but no solutions or options offered.
After searching other sites, I drained and flushed my pressure tank; only to now have short cycling issues start with the pump.
I located a video dealing with changing a pressure switch. In it, mention was made as how to properly drain and fill the expansion tank. and what happens if you don't do it right.
As your site comes up quite a bit when a Google search is made dealing with this, please allow me to submit the following for you to add to your "causes for short cycling" page.
When the pressure tank is drained, either for work (replacing gauge or switch) and likely even for the recommended regular (annual) maintenance to drain dirt build-up (which apparently reduces the possibility of the base of the tank prematurely rusting out) It is necessary to also drain the air pressure in the tank. This will allow all of the water to drain. If this is not done, water will still remain in the tank.
When the tank is filled with water again, it will appear to fill regularly up to about 30 lbs. at which point the needle on the pressure gauge rapidly shoots up to 50 - 55 lbs. and the pump shuts off. When water is first run, there seems to be proper water pressure at the taps, but this drops off very fast, and the pump begins to short cycle. This is because of the water still in the tank and the apparent air-lock this has created. When the tank was refilled (without having had all the pressurized air drained) the pressure tank did not properly fill and only the house lines were pressurized. When the tap was open this causes the pressure to rapidly drop, causing the short cycling.
To avoid this: Turn off supply valve to house, after pressure tank. Drain tank. Drain air pressure from tank. Re-pressurize tank.
Turn well pump back on and allow to re-fill with water (gauge should now fill slowly and steadily to set cut off point).
Open supply line tap to house.
To confirm proper operation and no more short cycling, open tap in sink and monitor gauge. All should operate properly now.
Based on the number of similar questions regarding this situation I came across while searching for answers, I'm sure this will come in handy.
Continue reading at WATER TANK AIR, HOW TO ADD or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
Question: well pump is short cycling every 2-3 seconds and we are not finding air pressure in the bladder. I keep emptying air out and the problem remains
Good morning, I have a rubber bladder tank, water is pumped from a deep water well. We seem to have a problem, the tank was fitted but kept having to be bled monthly as air was in the tank, last week we emptied the tank and found no air pressure in the bladder, so we pressured up the bladder, and now we find its recycling all the time every 2-3 secs when running a house tap. I emptied the air out of the bladder, but re-cycling fault is still there. Help please. I am not a plumber, and there is no decent plumber here in the Philippines! - John Nieurzyla
(July 25, 2012) Lorne said:
N.E. Ontario camp. Pump recycles every second when tap is on. Pressure tank seems to be half full or more with water. Cannot measure pressure with guage most of the time. Cannot release air when depress small needle in air valve. Is the air valve and/or diaphram shot ? Pump kicks in at 25 PSI. Runs up to 40/50 PSI, then quickly slips down to just over 30 PSI. Can't tell what pressure in system ?
(June 1, 2014) Joe T. said:
My well pump cycles on off every second when it cuts on at 20 psi but it still fills the tank and cuts off at 40 psi. I checked the pressure in the bladder and it is 18 psi. When doing this I obviously drained the tank and when I turned the pump back on it ran as normal no cycling. After that when it cuts on at 20 psi it short cycles again on and off every second as its filling. If I turn off the breaker and let the tank run down to no pressure it will again work normally when turned back on.
No cycling. The next time you run water and it reaches the 20 psi cut in pressure it short cycles every second as its pumping up to 40 psi. The short cycling is every second a constant on and off but the tank will fill. I replaced the pressure switch but it did not fix the problem. I turned off the breaker and ran the tank down to no pressure and again it pumped as it should no cycling. However in normal operating mode on at 20 off at 40 it short cycles every second as filling the tank.
(June 8, 2014) Chuck said:
My water pressure has surges. Can hear it surging every couple of seconds. When I look at the pressure gauge it is bouncing back and forth from about 30 to sixty, kicking the pump on and off quickly. Also, have been running out of water about once a week. I was wondering if low water in the well, might cause the surging, or if a bad tank that is surging could be the cause of the total loss of water. Could the well have water and the tank just not be filling up for some reason or more than likely well going bad? Thanks.
Reply: Check for a water-logged pressure tank.