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Photograph of a clogged water filterDiagnose & Fix Water Pump Short Cycling

  • WATER PUMP SHORT CYCLING DIAGNOSIS TABLE - CONTENTS: Table of all known well pump short cycling causes & diagnostic & repair steps. What causes the water pump to turn on and off too often or too rapidly? How to diagnose & correct short cycling "on-off" of the building water pump
  • POST a QUESTION or READ FAQs about troubleshooting well pumps that turn on and off too often - short cycling water pumps
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Well pump on-off rapid cycling diagnostic table:

This well pump problem table describes the steps to diagnose and cure all known causes of well pump short cycling - what causes the well pump to run too often.

Here is a table of all known causes of well pump rapid cycling. For each cause the table provides a diagnostic procedure and recommends a repair procedure.



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Well Pump Short Cycling Diagnostic Guide - What to Check, How to Fix

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.

If this is the problem with your water pump, you can use the diagnostic table below or for more explanation see our description of the most
common WATER PUMP SHORT CYCLING CAUSES.

If you are not sure what "water pump short cycling" means or how it is recognized,
see SHORT CYCLING WATER PUMP.

Well Pump Short Cycling Diagnosis: Things to Check if the Well Pump Runs Too Often

Symptom Diagnosis Repair
SHORT CYCLING / pump turns on & off rapidly or too frequently

Water pump turns on and off too rapidly or too frequently. On/off every 30 seconds or less.

Read in depth on causes and cures of well pump short cycling on and off - the links at right are an alternative to using this more concise diagnostic SHORT CYCLING PUMP TABLES below on this page.

Usual cause: water-logged water pressure tank.

See WATER TANK AIR, HOW TO ADD

For thorough diagnostics of pump short cycling, see WATER PUMP SHORT CYCLING CAUSES

The items below are not short cycling water pump problems

INTERMITTENT CYCLING pump

The water pump runs for no apparent reason, when no water is running - pump is not cycling on & off rapidly - pump turns on and goes through a cycle at odd times.

For pumps that run for no obvious reason see
INTERMITTENT CYCLING WATER PUMPS

For occasional complete loss of water pressure see WATER PRESSURE INTERMITTENT LOSS

NO WATER, PUMP ON

Lost water pressure

Water pressure has stopped completely, pump is running.

Watch out: Turn OFF the pump to avoid damage.

WATER PUMP WONT STOP RUNNING

TABLE 1: PUMP WON'T RUN, WON'T STOP, or CYCLES

NO WATER, PUMP OFF

Lost water pressure

Water pressure stopped completely, pump doesn't turn on.

NO WATER PRESSURE

WATER PUMP WON'T START

TABLE 3: PUMP RUNS, NO WATER or INSUFFICIENT WATER

WEAK WATER

Poor water pressure

Water pressure is weak at some or all fixtures.

Just at some fixtures: look for a closed valve, blocked elbow or piping downstream from last point where water is also routed to fixtures with good pressure

At all fixtures: look for clogged water pipes, improper pressure switch settings, clogged water filter

TABLE 2: PUMP RUNS, WEAK or NO WATER PRESSURE

WATER PRESSURE BAD at SOME FIXTURES

 

Water Tank Problems - USUAL CAUSE of SHORT CYCLING well pumps

Symptom or Cause Diagnostic Procedure Repair Procedure

WATER-LOGGED TANK

Pump cycles on and off rapidly

Pressure tank has lost its air charge because of a bad air volume control (for tanks that have no internal bladder) or because of a damaged water tank internal bladder.

Water tank will be heavy, condensation line will be high on the tank, well above the tank's mid point.

See SHAKE THE WATER TANK? - is it full of water?

See WATER TANK AIR, HOW TO ADD

For thorough diagnostics of pump short cycling, see this separate diagnostic article
at WATER PUMP SHORT CYCLING CAUSES

TANK AIR PRE-CHARGE too small

Water pump cycles too rapidly: the air charge is too little, or air has been lost from the tank.

Water pump does not turn on and pressure is above the pressure control cut-in setting: the tank air pre-charge is set too high.

Rapid cycling: see WATER-LOGGED TANK instructions just above,
OR for bladderless tanks see WATER TANK AIR VALVE REPAIRS.

No pump turn-on: set the water pressure tank air charge to 2 psi below the pressure control switch cut-in pressure.

TANK LOCATION

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 a REPLACEMENT WATER TANK
Water Pressure Tank Frozen Frozen water pipes at the outlet of a water pressure tank or a frozen water pressure tank outlet tee, or a frozen water pressure tank itself can all case water pump short cycling. Details describing this problem, its occurrence and repair are
at WATER TANK or TANK TEE FROZEN

 

Water Piping Problems - short cycling if leaks are extreme

Symptom or Cause Diagnostic Procedure Repair Procedure

WATER PIPING

Blocked water piping, clogged water filter or other water treatment equipment

A blocked or clogged water filter or pipe or other water treatment equipment close to the water pressure tank can cause very rapid on-off cycling of the water pump,

particularly if the filter, valve, or equipment is located between the water pump and the water pressure tank.

Watch out: turn off the pump right away to avoid damage.

Check the order of installation of equipment.

Be sure at least one clear water piping pathway is open between the water pump outlet side and the water pressure tank inlet side.

Replace a dirty, clogged, or suspect water filter cartridge.

See WATER FILTERS, HOME USE

and CLOGGED SUPPLY PIPING.

 

Plumbing piping or fixture leak on the discharge or supply side of the system 

A plumbing supply piping leak or running toilet can lead to frequent cycling of the water pump.

Shut off all of the fixtures in the plumbing system at their local shutoff valves. If no shut off valves are installed or if they are stuck, install or repair them at the next opportunity.

Listen for leaks. Check for running toilets by using a small amount of food coloring or septic dye dye in the toilet tank

. If colored water appears in the bowl the toilet flush valve is leaking.

Repair any plumbing leaks or leaky fixtures.

TURNING WATER SUPPLY BACK ON when de-winterizing

WATER SUPPLY / DRAIN PIPE LEAK TYPES

PIPING in BUILDINGS, CLOGS, LEAKS, TYPES

WELL PIPING LEAK DIAGNOSIS

Piping or fitting leak on the suction side or well side of the system

A leak in the well supply piping anywhere between the water pick-up point in the well bottom and the entry to the water pressure tank can cause loss of water pressure and water pump short cycling. (It can also cause air entry into the piping system).

For shallow wells install a pressure gauge on the suction side of the system.

If your well is a deep well (2-line jet pump) install a pressure gauge on the pump if an attachment point is available.

Let the pump run until it reaches its cut-off pressure. Note the pressure on the gauge.

Turn off power to the pump. Turn off water leaving the pressure tank and feeding the building - the valve on the "discharge" side of the system.

Alternatively, after closing the water valve on the output or discharge side of the system (stop feeding water to the building), use a bicycle pump to pump air into the system at the air inlet valve (if your system has one).

Pump to 30 psi.

Watch for a pressure drop. If the system won't hold pressure then there is ale a leak on the "suction side" of the water system.

Leaks may be a bad check valve, foot valve, or piping connection anywhere between the pressure tank and well bottom.

At AIR DISCHARGE at FAUCETS, FIXTURES
and

at WATER PUMP SHORT CYCLING CAUSES the role of a bad check valve or a hole in the well piping in causing well pump short cycling

Water and pressure are lost through the leak when the pump runs, and air may enter the piping when the pump stops - depending on where the leak is located.

First check and tighten all above-ground well piping connections to be sure nothing is leaking. Remember to check or replace any above-ground check valves that may be leaking.

Repeat the test.

If the system still won't hold pressure you will need to pull the well piping and check for a defective or leaky piping connection, leaky well piping check valve above ground, at the pump (if there is a valve there) or in the well at the foot valve.

WELL PIPING LEAK DIAGNOSIS

AIR DISCHARGE at FAUCETS, FIXTURES

WELL PIPING FOOT VALVES


WELL PIPING TAIL PIECE

CHECK VALVES, WATER SUPPLY

WATER PUMP PRIMING PROCEDURE

WATER VALVES

Closed or partly closed water supply valve

Be sure that you haven't forgotten and left a valve closed between the water pump and water pressure tank.

This can happen if someone closes a valve to perform other work on the plumbing system and forgets to open it again.

Be sure at least one clear water piping pathway is open between the water pump outlet side and the water pressure tank inlet side.

Watch out: turn off the pump right away to avoid damage.

 

Table of Detailed Water Delivery Problem Troubleshooting Procedures

Symptom or Cause Diagnostic Procedure Repair Procedure
AIR DISCHARGE at plumbing fixtures 

Inspect the air volume controls, snifter valves, automatic air insertion devices on the water pressure tank if your water tank does not use an internal bladder.

Inspect for a ruptured bladder or an older air volume control or snifter valve that should have been removed when the bladder-type tank was installed.

AIR DISCHARGE at FAUCETS, FIXTURES

TANK LEAKS

Water pressure tank leaks

Loss of air charge in the water tank

Inspect the water pressure tank for obvious perforations or severe rusting.

Apply soapy water to the entire surface of the water tank, especially above the water line. You can spot the water line as the high point of condensation on the water tank exterior.

Remember to check also for leaks at the air valve(s) used to pump air into the pressure tank.

Temporary repair of a rust-perforation of a non-bladder type water tank may be possible using a sheet metal screw and neoprene or rubber washer. But the tank needs replacement.

WELL TANK RELATION to WATER PRESSURE

SHAKE THE WATER TANK? - is it full of water?

Note that for water tanks that do not use an internal bladder the air charge is gradually lost to absorption into water passing through the tank.

This is not a leak. Check for a bad air volume control.

WATER TANK AIR VALVE REPAIRS
.

Pinhole leak in water pressure tank bladder 

Water-logged internal-bladder type pressure tank with a pinhole leak in the bladder may accumulate water inside the bottom of the tank (where air should be) and thus cause water pump short cycling.

But because water leaks into the tank's air space just at higher tank pressures and does not easily leak back into the pinholed bladder (where water should be in most designs) when we depress the air valve atop the tank it may not squirt water -just air.

If the tank is abnormally heavy even when drained we suspect this problem.

PINHOLE LEAKS in WATER TANK BLADDER

Water pressure tank bladder damage or leak

If the pressure tank is a "captive air" or internal bladder type tank, a leaky or damaged bladder can cause the water tank to become waterlogged and cause short cycling of the water pump.

Most bladder type water tanks contain water inside the bladder and air outside it. Be sure you checked the tank for apparent leaks as we described in the step above.

If your bladder type water tank is fiberglass it may be reversed in design, containing air in the bladder and water in the tank. Still a damaged bladder leads to a waterlogged tank.

A leaky or damaged water tank bladder needs to be replaced or the entire assembly replaced.

BLADDER TYPE WATER TANK FAILURES


REPAIR for BURST TANK BLADDER

Defective or leaky Air Volume Control

A leaky or failed air volume control (AVC) will lead to a waterlogged water tank as the control is no longer doing its job of maintaining the tank's air charge. (Not all water tanks have an AVC).

Inspect the AVC and its tubing for rust or water leaks. But an air leak may also be present - see our next step below.

Repair or replace any suspect air volume control components.
WATER TANK AIR VOLUME CONTROLS

Optionally, remove and plug the AVC fittings and change to an alternative method of maintaining the air charge in the pressure tank:

Use the water tank air inlet valve - details are at WATER TANK AIR INLET VALVE

Drain the water tank - details are at WATER TANK AIR ADD BY DRAINING

Air volume control tubing leak:

Disconnect the air volume control at the water pump and plug that opening.

If the water capacity improves there is probably a leak in the tubing or the control.

Tighten all tubing fittings, be sure the tubing is correct diameter and proper fittings are used so that there are no air or water leaks.

WATER TANK AIR VOLUME CONTROLS

 

Water Pump Pressure Control Switch - usually not cause of short cycling pump problems

Symptom or Cause Diagnostic Procedure Repair Procedure

PUMP CONTROL SWITCH

Pressure control switch differential adjustment too small 

Water pump turns on and off too frequently when water is being run in the building

Pressure control switch adjusted incorrectly: Differential too small

In a different problem case, setting the differential range too small combined with a high cut-out pressure on some pressure control switches can cause the water pump to run continuously.

In adjusting the pressure control switch differential nut#2, if you completely loosened the smaller nut #2 (differential adjustment) so that the pump differential between cut-in pressure and cut-out pressure is very small the water pump may short cycle on and off rapidly when water is being run in the building.

Re-adjust the pressure control switch.

PRESSURE SWITCH NUT ADJUSTMENTS

Bad pump pressure control switch

Check the switch contacts for burning or wear Adjust or replace the pressure control switch. Temporary emergency repair by cleaning the switch contacts may be possible. See

PUMP PRESSURE CONTROL REPLACE
Manual reset required on some pump pressure controls 

If your pump has an electrical low water protection device that component may shut down the pump to protect it from damage if well water level or flow rate falls too low.

That pressure control switch may shut down the pump and require manual re-setting

WATER PUMP PROTECTION SWITCH
Bad pump pressure control switch tubing Check the tubing connecting the pressure switch to the pump housing for clogging Clean or replace the tubing and be sure the connections are not leaky - an air leak will prevent the switch from sensing pressure properly.
PUMP PRESSURE CONTROL REPAIR
Bad pump pressure control switch settings

Especially if someone has been fooling around with the pump pressure control cut-in and cut-out pressure settings, the difference between the cut-in (low) and cut-out (high) pressures may be set too small.

Check the water pressure as the pump cuts in and again as it cuts off.

 

 

Typically we see about 20 psi difference between the pump cut-in and pump cut-out pressures.

If you are finding less than this, adjust the pressure control switch accordingly.
WATER PUMP PRESSURE CONTROL SWITCH

PRESSURE GAUGES

PRESSURE GAUGE ACCURACY

PUMP PRESSURE CONTROL ADJUSTMENT

Watch out: Don't set the cut-out pressure too high or the pump will just keep running. Also, pump gauges are not always accurate.

You may need to use a static pressure gauge on a nearby hose fitting such as for the washing machine. WATER PRESSURE GAUGE ACCURACY

Short cycle stop valve stopped working  If a well pump short cycling cycle stop valve has been installed and the system is relying on this device to cure a well pump cycling on and off too often, check that the valve is installed correctly and is working properly. See SHORT CYCLE STOP VALVE

 

Well Pump Motor Problems - usually NOT short cycling problems

Symptom or Cause Diagnostic Procedure Repair Procedure

PUMP MOTOR

Bad water pump, pump start capacitor, or pump controls

Especially if the water pump has been suffering a prolonged history of rapid short-cycling on and off or if a pump motor is old, worn, hard-starting, or has failing bearings, the pump's electrical controls such as a start capacitor used on some pump motors may have failed.

Thanks to reader M.H. for this tip 7/23/14

Check for a pump drawing abnormally high current - signs of wear or motor failure.
ELECTRIC MOTOR DIAGNOSTIC GUIDE

Check for a bad start capacitor.

CAPACITORS for HARD STARTING MOTORS

Well Pump Wiring Problems

blown fuses, tripped breakers, low pump output

Well pump keeps tripping circuit breaker or blowing fuses, or well pump fails to deliver water at normal flow rate and pressure.

Look for low supply voltage, burned control switch contacts, damaged well pump wiring, or a damaged well pump itself.

A recent lightning strike can also damage well pumps or wiring leading to these symptoms.

See WATER PUMP WIRING DAMAGE

Also see

WATER PUMP REPAIR GUIDE

ELECTRIC MOTOR DIAGNOSTIC GUIDE

 

If the Well Pump Motor Runs for no apparent reason If the pump runs too often the cause may be a control problem, water tank problem, piping problem, or a well problem.

INTERMITTENT CYCLING WATER PUMPS if the pump runs at odd times for no apparent reason.

If the Well Pump Motor Keeps Running & Won't Stop

If the pump won't turn off the cause may be a damaged pump control, a plumbing or fixture leak, or a well problem.

Watch out: Turn OFF the pump to avoid damage.

Watch out: If the pump motor won't shut off you should turn off electrical power to the pump to avoid damaging it, then diagnose the problem.

WATER PUMP WONT STOP RUNNING

WELL PIPING LEAK DIAGNOSIS

Other causes of well pump short cycling that we have not mentioned: ask your plumber. And CONTACT us to add that helpful information for others.

Some of the well pump troubleshooting suggestions in this list can be found at the Betta-Flo Jet Pump Installation Manual from the National Pump Co.

 

No Water Pressure, Pump is Running - these are NOT short cycling problems

Symptom or Cause Diagnostic Procedure Repair Procedure

LOST PUMP PRIME

Leaking foot valve in the well or leaking check valve at the pump

Pump runs, no water is delivered.

If the well pump frequently loses prime, there may be a leaky or failed check valve (at the pump) or foot valve (in the well).

If your jet pump (above ground) incorporates a check valve at or in the pump that valve may have failed.

If there is no foot valve in the well (or if that valve doesn't work), the failure of the above-ground check valve at the pump can lead to short cycling or to loss of pump prime.

To examine the foot valve the well piping has to be pulled.

For this reason if you do pull the well piping we recommend replacing the foot valve rather than having to repeat this procedure again soon.

Remember to inspect the piping, connections, tailpiece, ejector, and all components in the well.

See
SHORT CYCLING CAUSE: WELL PIPE LEAKS

WELL PIPING FOOT VALVES

WELL PIPING TAIL PIECE

CHECK VALVES, WATER SUPPLY

WELL PIPING LEAK DIAGNOSIS

WellMate  fiberglass water pressure tank (C) D Friedman J Hafner

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,
SHORT CYCLING CAUSES
describes the most common causes of this problem.

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

CONTACT us by email with questions or suggestions about this list.

...


Continue reading at WATER PUMP SHORT CYCLING - PIPE LEAK 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 INTERMITTENT CYCLING - pump runs for no reason

Or see WATER PUMP SHORT CYCLING FAQs

Or see WATER PUMP REPAIR GUIDE - home and also WATER PUMP DIAGNOSTIC FAQs

Suggested citation for this web page

WATER PUMP SHORT CYCLING DIAGNOSIS TABLE 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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