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Well Pump Short Cycling FAQs

  • SHORT CYCLING WATER PUMP FAQs - CONTENTS: more diagnostic questions & answers about the cause & cure of a well pump that is turning on and off too frequently, too often, or too rapidly.
  • POST a QUESTION or READ FAQs about diagnosing and repairing a short-cycling well pump: how to fix a well pump that keeps turning on and off too frequently
  • REFERENCES
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Short cycling water pump FAQs:

These diagnostic questions help explain why a water pump turns on and off rapidly or too often.

This article series defines short cycling or rapid cycling well pumps and the various causes and cures for that problem. We explain why rapid on-off switching of the water pump can be harmful and how it also affects building water pressure. Short cycling usually indicates the need for air in a water pressure tank.

The illustration of the parts of a well and pump system shown at page top is courtesy of Carson Dunlop Associates, a Toronto home inspection & home inspector education firm.



Green links show where you are. © Copyright 2017 InspectApedia.com, All Rights Reserved.

Water pump short cycling FAQs

WellMate  fiberglass water pressure tank (C) D Friedman J HafnerSeveral alternative procedures for adding air to a water pressure tank are described below along with advice about what to do when things go wrong, such as finding air and water leaks.

Reader question typical of pump short cycling problems:

9/1/14 william said: my well pressure switch keeps clicking on and off rapidly

If this is the problem with your water pump, WATER PUMP SHORT CYCLING CAUSES describes the most common causes of this problem.

We also provide a complete WATER PUMP SHORT CYCLING DIAGNOSIS TABLE that lists all possible causes of well pump rapid cycling on and off.

Short cycling water pump means that the water pump or well pump is turning on and off too frequently. How frequently is that? There's no single exact answer but generally a well pump or water pump that is pressurizing and re-filling a water pressure tank (when no plumbing fixtures are at the same time using water) will run 30 seconds or a minute or longer.

A pump that's zapping itself on and off every 15 seconds or less is short cycling.

Watch out: A water pump that's turning itself on and off very rapidly - every second or less may have a different problem: a blockage. You should turn that pump off immediately to avoid damaging it.

These questions & answers on how to diagnose & fix a well pump that's cycling & off too frequently were posted originally at SHORT CYCLING WATER PUMP. If you are not sure what "water pump short cycling" means or how it is recognized, please read that article first.

First, to avoid confusion, let's mention two different water pump problems.

Intermittent water pump cycling which is discussed at INTERMITTENT WATER PUMP CYCLING means that the water pump comes on for no apparent reason.

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

On 2017-03-24 18:44:28.310893 by (mod) re: The issue is that the pump kicks off at 35 psi (not 48 like its supposed to)

Nina

Searching (in the search box just above) InspecApedia for "adjust pressure control switch" finds PRESSURE SWITCH NUT ADJUSTMENTS at http://inspectapedia.com/water/Pressure_Switch_Nut_Adjust.php

Please take a look at that procedure and let me know how that works for you.

On 2017-03-24 18:00:49.344893 by Nina M.

We just replaced an older 20 gallon water tank with a 32 gallon water tank in a home we just purchased. We are still using the jet pump (shallow well) and pressure switch (Square D single post switch located at pump).

At the current adjustment, the pump kicks on at 28 psi and we deflated the empty tank to 26 psi. The issue is that the pump kicks off at 35 psi (not 48 like its supposed to), and we feel like the tank is not at its full capacity.

On 2017-03-02 17:34:04.146821 by (mod) re: Pump goes off and on

Search InspectApedia for WELL PUMP SHORT CYCLING

On 2017-03-01 16:25:40.580015 by Gerald bury

Pump goes off and on

On 2017-01-23 15:17:48.300003 by (mod) re: pressure tank re-charge time problems in Costa Rica

If the pump is taking less time to re-charge the water pressure tank and there is no water running in the home (or was none at times of previous comparison) then I suspect the tank is becoming waterlogged - the tank bladder may be torn or damaged.

If when the tank is "emptied" of water and at zero pressure it remains heavy it's probably still got water in-it and is waterlogged.

On 2017-01-23 by Ed

I am having problems with my 60 liter Varem bladder-style pressure tank. Everything worked fine for the first two years. But lately we are having the following problem: The length of time the pump spends charging up is getting shorter and shorter. So when everything is working well, it takes maybe 1 minute or a bit more to get the pressure up to 40 PSI. And the pump does not come on often because we don't use mush water.

But over time (2 or 3 weeks) the pump comes on more often and for shorter periods of time (10 seconds or less). Important point: the pump NEVER comes on at random times, as it might if there was a plumbing leak somewhere that I didn't know about. It ONLY comes on when we are using water water (flushing a toilet, running a faucet, etc.). Also, water does not come out of the air valve when it is depressed (horizontal tank).

When the short cycling is bad enough (like coming on every time anyone uses water for anything, and running for about 10 seconds) I "fix" the system. I turn off the power, close all valves bringing water to and from the tank save one going to a faucet. I open that faucet and let the water drain out. When it is done draining, I connect my air pump to the tank and turn it on. This causes much more water to come out of the faucet (maybe 60 liters worth!)

When there is no more water coming out, I turn off that water valve (and tap), and charge the system to the usual pre-charge of about 17 PSI (tank is set for 20/40). And it will be perfect for a few days, and then I will start to notice a gradual shortening of the amount of time spent charging up. And 2 or 3 weeks later, it will be done to about 10 seconds, and I repeat the whole procedure.

My tentative conclusions:

1. There is no plumbing leak that I am unaware of, otherwise the pump would cut on when nobody is using water.

2. There is a (pinhole?) leak in the bladder allowing water to gradually exit the bladder and enter the tank; that is why pressurizing the tank pushes so much water out of the open tap.

(The fact that eventually no more water comes out is proof that I have not left on some other valve by accident.) So I am now planning to replace the bladder (looks like a pretty easy thing to install).

But I wanted everyone's advice: Could I be missing something?

Thanks for your feedback. (Possibly relevant or not: I live in Costa Rica.

It is possible that the tank was sitting around for too long in poor conditions before it was purchased. It looks perfectly good on the outside even now, but maybe the bladder got hot, dry, moldy, or whatever and is now showing signs of its unhappiness.)

On 2016-12-13 by Anonymous

My pump is short cycling when water is on . I replaced water filter and the pressure switch. No change.

On 2016-11-01 by Tony

Pump goes off and on

We lost water pressure this morning. Then pressure came back after a while. Went in crawl space to the pump control, bladdered pressure tank,and pressure switch. I have a submersible pump, been in for 30+ years. About 3-4 years ago my pressure tank went bad and I replaced it and the pressure switch and guage. I was watching the pressure switch while somebody turned the water tap on.

The pressure went down slowly got to about 35psi, switch tripped on just like it supposed to. After about 5 seconds the pump shut off, not by the pressure switch though, It must be the control box or pump. After about a minute or minute and half the pump came back on and went the entire distance to about 55-58 psi then the pressure switch cut it off like normal. Any ideas Thanks

On 2016-10-26 16:16:57.930824 by (mod)

Marie, if the pump is short-cycling on and off the problem is more likely to be the one discussed in WATER PUMP SHORT CYCLING

Check that discussion before replacing the pump.

A very hot pump motor could mean the pump is seizing and needs replacement, but other causes such as running out of water or short cycling could be at fault. You need an onsite diagnosis before replacing the pump lest you waste the pump cost.

On 2016-10-26 16:15:13.987214 by (mod) re: sudden pressure loss

Re-Posting

AUTHOR:Marie (no email)

COMMENT:Suddenly, while in shower about 10 min.the pressure dropped, got out checked sink in kitchen very low.waited heard pump come on them in like 5 min shut down. Few minutes on then off.Went to basement out hand on it very hot..why is so hot and is that why it's cutting in and out.

Does anybody know do I need a new water pump.It's 1 year old.Need help.

On 2016-10-23 23:52:16.386033 by (mod) re: how do I get the right gap between cut-in and cut-out after I fooled around with the switch

Dan

Don't feel bad, I've done the same thing. Please use the search box just above to search InspectApedia for PRESSURE CONTROL SWITCH ADJUSTMENTS to see how to set the two nuts.

On 2016-10-23 17:43:38.885378 by dan

I adjusted my pressure switch (before knowing what I was doing)and now the the cut in is 50 psi and the cut out is about 51 psi. how do I obtain a 20 psi gap between them again? i have a Square D 9013FSG2M4 switch.

On 2016-09-25 (Mod) said: re: pump cutting in 5 psi over when it should

I'd first check that the switch hasn't been fooled with by me or someone. See the PRESSURE CONTROL SWITCH ADJUSTMENTS article at InspectApedia

If the pressure switch continues to drift off it's perhaps debris clogged or just needs replacement.

On 2016-09-25 13:06:57.201590 by Joe

I turned the water on and watched the pressure gauge to see when the pump kicks on, and it is kicking on at 35 pounds and the cut in on the switch is supposed to be 30 pounds and the pressure tank is set at 28 pounds. What is this telling me? Thanks

I must not be the sharpest pencil in the drawer, but I just re-read the short cycling segment and it is still short cycling.

I forgot to leave my name on the question that has just posted before this one.

I took the filter out and it still does the same thing. I don't think it is shutting off completely, it is running but it is pulsating. Is this called short cycling?

On 2016-09-25 03:13:42.824020 by (mod)

Joe,

Try putting the water filter in bypass mode, and/or removing the filter cartridge. Let me know if this makes a difference in how the pump behaves.

On 2016-09-25 02:54:04.039869 by Joe

I just replaced my pressure tank from underground to in my basement. It came pre charged with 38 pounds of pressure. My pressure switch has a 30/50 pound rating so I adjusted it accordingly to 28 pounds but my pump keeps short cycling until it reaches the 50 pound threshold and then it quits.

I am wondering if it will make a difference whether or not I put my whole house filter before the pressure tank, or should I have left it on the discharge side of the pressure tank?

On 2016-09-24 (Mod) said: re: can I just drain the tank to fix waterlogged tank short cycling?

Yes, a simple approach to getting air in the tank is to do what you describe. Get all the water out. Then close the drain and turn the pump back on.

On 2016-09-24 15:50:21.386041 by James

My galvanized tank is completely waterlogged, making the pump (in the house, deep well jet style) short-cycle. There's no AVC, Schrader valve, or fitting on the tank, and with this being a higher-pressure system, I'm told my tiny bicycle pump won't cut it.

Can I just turn off the pump's breaker, drain the tank with a garden hose, and turn it back on? Do I have to worry about losing prime?

Question: possible failed water pressure tank internal bladder causing short cycling?

I went down this morning and power of to pump. Close ball valve just after the switch and pressure tank and drained water out of tank. Took air pressure test on tank it there was nothing. I had actually done this a few weeks ago and had to fill tank up with air roughly 28lbs.

So have a air leak some where. Refilled pressure tank up to 28lbs today and did a soap test around valve stem and see no apparent leaks. So I leaning to having to replace the bladder. Its just over 10 years old, I read they hardly ever go bad. I would like to know your thoughts. ( since filling with air pump cycles normally) - Anon 7/9/12

Reply:

Indeed from reports here tank bladders do fail on occasion; in some water tank designs the bladder can be replaced without replacing the entire tank assembly.

Reader follow-up:

Yes I have read in numerous places that they can fail. This one is 11 years old, have one on order and hope it solves the problem. - Robert Lee

Question: when I attach a nozzle or sprinkler to garden hose the well pump no longer runs continuously

My shallow water pump runs just fine with a hose attached with no increased back pressure, but if I attach a nozzle or a sprinkler to the end of the hose, the pump will run for 30 seconds and then shut off. It cycles like that continuously. I have tried increasing and decreasing the air pressure in the bladder to different levels and it does not seem to correct the problem

. How do I know the correct air pressure? It is not written anywhere on the pump or the valve. Any other suggestions? - Dr. Louis Gotthelf 9/26/2012

Reply:

Louis,

If your water pressure tank has a proper air charge that will give the longest possible drawdown time and water volume before the pump reaches the cut-in pressure; I suspect that when there is no backpressure from a hose nozzle your water pump is running continuously - since it is not reaching the cutoff pressure;

When you attach the hose nozzle you are still running water pretty fast, but not quite so fast, so you draw down the water in the tank and the pump will cycle on and off as needed; Just be sure the tank has adequate air charge - that 30 seconds may be a bit short, depending on the size (volume) of your pressure tank.

Question: pump is slow to reach final cut-off pressure - not short-cycling

(Mar 3, 2014) Rich Maltese said:

I just replaced a pressure switch, tank and gauge. The pump starts at 30#'s and runs a few minutes to get to 48#'s, then it seems to take a few more minutes at least to get to 50#'s and shut off! even with water off. Is this normal, or do I need to adjust the pressure switch? The pressure in the tank I was set to 26#'s before filling it with water.

Reply:

Rich, it's not unusual for the pump to run longer at the very end of the pressure range if it's an older weaker unit or if the water supply in the well is limited. But yeah, if you can get to 48# quickly, I'd try dropping the CUTOUT down that 2 psi - it'll save work on the pump.

The tank pressure when water has run (and pump is off) until there's no pressure in the tank, should be set at 2 psi BELOW the cut-in pressure.

Rich this is not a short-cycling rapid pump on-off problem. But In the case you describe, when the pump runs for minutes or longer to get from 48psi to 50 psi, and presuming it's filling a typical not a very large water pressure tank, then you may be operating the pump cut-off pressure at near the edge of what the water pump is capable of achieving.

This symptom can occur due to a worn or damaged pump impeller or low voltage or a damaged pump motor. More subtle, a leak in the well piping might also contribute to this symptom.

Question: pump & water pressure drops to weak then comes back - water pressure comes and goes

(4/28/2014) Eric Sekeres said: so here is my problem. In the last week my irrigation system was doing weird things. I turn it on and the water comes out full strength. Then water pressure drops to very little and then comes back. Is it a bad valve or bladder or some other problem. My neighbors have full water pressure so I think the aquifer is strong. Need help. I'm handy but when it comes to sprinklers I am the village love. Any help is appreciated.

Reply: this is not short cycling of the pump it's a loss then return of water pressure.

Eric you describe water pressure that "comes and goes" - a problem we discuss and diagnose in a related article. Please see

Since you think there is no problem with the well flow rate itself, I'm guessing your pressure control switch sensor port is clogged but it could be something else.

Question:

(June 1, 2014) Ernie said:

Short recycling with exterior sprinkler on alone but not with underground yard sprinkler also on

Reply:

Ernie that's baffling. I'm stumped.

Question: pump runs constantly after flushing toilet

(June 4, 2014) Rachel said:

I just moved into a very old farm house. The home is probably over 100 years old. I notice the water/well pump comes on constantly after flushing the toliet. It runs for a few seconds, stops, starts, etc. Its pretty intermittent also. It usually does the starting/stopping for a good 15-20 minutes after we flush.

It also comes on when we run water from a faucet as well. It even comes on randomly when no water is being run or the toliet has been flushed. I have called the landlord several times about this.

He checked the toilet for leaks by putting blue food coloring in the tank? Not even sure what to say anymore. He told me to try & "jiggle" the toilet handle to see if that helped with the pump turning on & off repeatedly? I dont know of this is normal, but, it doesnt seem to be.

Im worried the constant running of the pump will jack up my electric bill. The landlord just doesnt seem to want to replace it. He had someone come over to look at it yesterday, although, I dont think it was a plumber. He said it seemed ok when he looked at it..but, it is still running alot. Please help. Thank you!

Reply:

I suspect a water-logged pressure tank, Rachel. Try the suggestions in the article above.

If you want to know if the problem is at the toilet - lift the lid off the toilet tank (don't drop it!) and look inside the tank.

Then see TOILET RUNS CONTINUOUSLY

Question: pump stutters at shut down

(July 12, 2014) john said:

the pumps start at 30 pds shut off at 38 pds for a second then staets back up to 45pds shut off replaced tank and pressure tank

Reply:

Check for burned pump pressure control switch contacts or a clogged pressure sensor port on the pump switch - or try replacing the switch.

Question: losing pressure, don't think it's the foot valve

(Aug 18, 2014) mike said:

Bad Pump? Bad Something Else?

I have a deep well pump with two lines. It is about 13 years old. Tank pressure is 28psi and the pump is set to 30/50.

Last year I was losing pressure (water) without using any, and the pump would kick in. The problem was not the water tank. So I had the foot valve replaced. That solved the problem for about 6 months. This April I started to lose pressure again. It cannot be the foot valve this time (or the last time), as when I unplug the pump and let all the water out and prime it, that solves the problem.

Everything was alright for the next 4 months, until this August, where the pump would kick-in every 4 hours for a few days, then every 3 hours for a few days. And finally after about a week, it was kicking-in every 20 minutes. So I repeated what I did in April. Now it kicks in every few hours. Sometimes it does not kick-in at all.

I don't know what the problem is. Obviously, foot valve is working, and there cannot be any holes anywhere in the lines, as if that was the case I will be losing water no matter what I did. Do you have any idea what the problem may be? Could it be the pump? or....

Reply:

Bad

Provided we've eliminated a leak in building piping or water use there by shutting off water into the building, if the pump continues to cycle on I suspect a leak anywhere between the pressure tank and the very bottom of piping in the well. The leak could be in well piping or a bad foot valve, even in the pump body itself.

Question: Flexcon Industries PC122R tank, getting air in water lines

(Oct 29, 2014) Bill said:

I have a well with a Flexcon industries PC122R model tank volume 33.4 gal. we have been getting a lot of air in the water line but when I went out to look at the tank I heard water running in the line coming from the well and the pressure gage was slowly going down with no water running in the house. I am thinking that the valve that stops backflow is bad but I have no idea of where to look or how to prove what is going on. I need help.

Reply:

Bill

A well piping leak or a bad foot valve could indeed be the trouble

Solutions are at AIR DISCHARGE at FAUCETS, FIXTURES

Question: how does water get into the top of a bladder tank

(Jan 4, 2015) Anonymous said:
How can water get into the top of a bladder tank

Reply:

Anon: if the internal bladder has a hole, tear, or leak then water can leak into and ultimately fill the air-area of a water pressure tank - if the tank is the type that uses an internal bladder. You'll need to replace the tank bladder or replace the entire pressure-tank assembly.

Question: how to check the water pump without removing it from the well

(Feb 23, 2015) Coach J said:
Is there a way to check pump without pulling up?

Reply:

Yes Coach.

There are both pump controllers that monitor the electrical circuit and pump experts or electricians who know how to make these tests using a DMM or VOM. For example, comparing current draw (amps) when the pump is running can indicate if it's pushing water, has a broken impeller, or is running dry.

Question: accuracy of pump controls & gauges

(Nov 2, 2015) Pierre said:
The jet pump cycles normally to 50PSI. At cut off it loses 7PSI, then remains stable. I have changed the tank, switch and all the piping. I even injected 50PSI air into the system to check for leaks. The system remain at 50psi. I did notice small air bubbles in system so did a complete backwash.

The pump appears to take longer to cycle but works fine until cut off. I can hear the water going back into the system at cut off until pressure becomes constant at 43PSI. What can cause this issue? thank you Pierre

Reply:

Pierre:

I find that pressure gauges and controls are not precise lab-type instruments; it would be common to read a few psi more when the pump is running than right after the pump shuts off at the end of an on-cycle. As long as pressure does not continue to drop I don't look for a leak. However in the case you describe - hearing water going back into the system, it sounds to me as if there is a weak or bad check valve or foot valve.

Question: if there is just one pipe connected to my jet pump does that cause short-cycling?

(Dec 9, 2015) Gordy said:
My water tank has single pipe that acts as both an inlet and outlet. This does not seem right. Does this relate to the pump short cycling?

Reply:

No Gordy, what you describe is normal and would not affect short-cycling. Short cycling will usually be caused by a tank that has lost its air charge.

When the pump has reached cut-off pressure and stopped, and then when you turn on water, compressed air in the pressure tank sends water out of the tank into the building.
As pressure in the whole system falls, the pressure switch turns on the pump.

The pump simultaneously sends water into the home and back into the pressure tank through that same pipe connection (usually at the tank bottom). If the usage rate of water is less than the pump supply rate the pump will get ahead, reach cut-off pressure and stop running and the cycle will begin again. If the water usage rate is equal to or greater than the pump supply rate the pump will keep running all the while that water is being run.

It is true that in a different design, a water tank may have separate inlet and outlet piping connections though that's less common. But the system will work the same way.

Thanks for asking. Let me know if the explanation I give is not clear.

Question: pump keeps turning on and off as the washing machine fills - caused by clogged water filters?

(Jan 4, 2016) Rosemary said:

We Brought a new Fisher and Pykel front loader machine. It has filters in the hoses.

We have rain water tank and pump. When the washing machine is doing a load of washing our pump keeps cutting in and out. Is it the filters on the machine. Our old Hoover top loading machine never caused it.

Reply:

If your water pump is short cycling the problem is more likely to be one of the causes described in the article above. Even if the filters (probably strainer screens) in the clothes washer hoses were slowing the water flow into the washer, that would not make a pump cycle on and off rapidly, in fact it would reduce that effect.

UNLESS: the filters are actually very clogged. A very clogged filter that blocks output from a water pump can cause very rapid on-off cycling and risks damaging the pump and its control switches or relays. Try changing the filters.

Question: water pump short cycles at the cut-off pressure

(Feb 5, 2016) Karl Greenman, said:
Waterpump runs when it gets up to turn off it short cycles and will not stop

Reply:

Karl

For dome good diagnosis and repair suggestions please search inspectapedia.com for

PUMP WON'T STOP RUNNING

I suspect a bad control or a pump having trouble reaching the cut off pressure.

Check for burned contact points in the pressure switch.

Question: water squirts out of the air valve on my pressure tank

(Apr 6, 2016) Rich said:
I have a bladderless pump that is short-cycling. There is a Schrader valve on the pump side of the one-way valve. When I push in the valve stem while the motor is off, water squirts out of the valve. Shouldn't I expect it to be sucking in air instead? Is my one-way valve broken?

Reply:

I'm not sure, Rich. On most pump systems that Schrader valve is there to permit adding air to an air pressure reservoir in the system. Your "bladderless pump" (I'm not quite sure what that is) may include a small air reservoir in its control system. If water squirts out of the air valve, that reservoir has no air in it (that can cause short cycling).

(Apr 6, 2016) Rich said:

Sorry, I meant bladderless tank. I have a bladderless tank with a US gauge type WJ on it and a snifter valve on the one-way valve on the pipe going into the tank.
The pump is short cycling. I can drain the tank to get air back in it as a temporary fix

I went to change the snifter valve to fix this and noticed it squirted water when depressing the needle when the pump was off. I thought the snifter valve was there to let air into the pipe when the pump turns off. Is this not the case?

Sounds like a waterlogged tank;

If you have a submersible pump your well may use a snifter valve but you're only seeing the above-ground part of the system.

Search InspectApedia.com for SNIFTER VALVE to read the details

On a bladderless type water tank if water squirts out of the air valve that is on the tank, then the tank is probably water-logged.

Question: captive air tank short cycling when water is being run


[delete] (Apr 21, 2016) Dave said:

My captive air tank started shot cycling last week (25-30 secs when water on) and within a week it has reduced to a second or two when water on. I checked the pressure with a tire gauge and I'm getting nothing. The pump cycles from 20-40 psi according to the gauge.

I tried to add air but the stem seems to be blocked and won't let air in? Is this possible? I didn't drain tank yet to properly reset was just trying to add a little for a quick fix to get through the morning. Any thoughts?

Reply:

Dave:

If your pressure tank uses an internal bladder and water comes out when you depress the pin in the air valve, the bladder has burst.

Question: seasonal cabin water tank has air but is short cycling

(May 22, 2016) Anonymous said:
My pressure tank is short cycling. I do not know if I have a bladder or bladder's tank. Its at a seasonal cabin. Last Fall I totally drained all water in the system, This spring the pressure tank had zero air pressure. I charged it tp 50 psi. After a week the tank is at 45 psi but is still short cycling.

No water came out of the shraeder valve when i charged the tank. Any ideas

Reply:

x

Question: well company says I need one or two additional water pressure tanks because of short pump on-time

(May 24, 2016) Dirk said:
Good Day,

I was just told by a well Company I needed one or two! more bladder tanks added to my one 65 Gallon bladder tank, because of my 5 hp. Submerged pump.
His reasoning was that a run time of less than one min. would cause the pump to overheat.

The large pump is for a 3-acre irrigation system, also the home. However, the pump is under water shouldn’t the heat transfer be sufficient to cool it, the pump does not short cycle.
What is your option 1 or 2 more, or is one 65 gal good enough?
Thank you

Reply:

50 psi in an empty waer pressure tank is overcharging

Little or no water enters the tank

Set the tank pre-charge to 2 psi below the pressure control switch CUT-IN pressure. Typically that'll be 28 psi for a 30 psi cut-in pressure.

Question: pump short cycles until I run a lot of water outside

(June 10, 2016) MR said:
My pump is short cycling when I use the kitchen sink faucets, shower,washing machine and dishwasher. Not short cycling when free flowing water supplies such as outdoor lawn spigots, toilets, and bath tub. I am using a bladder and and pump system.

Reply:

That may be because when you run water fast enough the pump can never reach its cut-off pressure.

I suspect a damaged bladder in your water tank and/or a waterlogged tank, or a bladder that's stuck and not letting water into the tank.

Question: changed points, replaced tank, pump is still short cycling

2016/07/11 brenda said:
my pump is short cycling. Changed points cause was told that was the problem it did not solve problem. Then was told it was my tank, so emptied it and hooked back up still doing same thing and then they said I needed new tank. I replaced it and still doing same.

Now they said I need to replace compositor and then maybe pump. I'm lost can someone please help.

Reply:

Good grief. Talk about "shotgunning" a repair diagnosis.

I don't know what part is being referred-to by the term "compositor" and would sure appreciate some clarification and a photo. That might permit further comment.

While a new internal-bladder type tank (or getting a proper air charge in a bladderless water tank) will usually solve the short cycling problem, there could be another problem. If you consider that what turns the pump OFF is the pressure switch sensing that pressure is at the cut-off point, you'd look for a condition that causes that to occur too quickly.

Examples are listed in the article above. Look for a blockage that prevents water from entering the new tank (a bladder stuck to itself); look for a loose wiring connection or a defective pressure switch.

Changing the "points" (just the electrical contacts) in a pressure switch in response to short cycling is in my opinion bad advice since more often the short cycling problem is either a waterlogged pressure tank or a pressure switch that is debris clogged. The water pressure is communicated to the bottom of the switch through a small tube, typically 1/8" diameter that can itself be clogged, or the even smaller water pressure sensing opening in the bottom of the pressure switch can be clogged, or the switch diaphragm may be bad.

Change the pressure switch and be sure that its mounting tube is not debris clogged. If that fixes the problem, in the future you will want to listen to whomever was giving you the earlier (and expensive, and incorrect) advice with a cocked ear of caution.

...


Continue reading at WATER PUMP SHORT CYCLING CAUSES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see SHORT CYCLING WATER PUMP - home

Or see WATER PUMP SHORT CYCLING FAQs for more well pump short-cycling on and off diagnostic questions & answers

Or see

Water Pump Short Cycling Articles

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SHORT CYCLING WATER PUMP FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER SUPPLY, PUMPS TANKS WELLS

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