Frequently Asked Questions
Find answers to common questions about pumps, motors, water systems, troubleshooting, repairs, and replacement solutions from the Miami Pump & Supply team.
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Pump Noise, Running Problems and Prime
Why is my water pump making so much noise?
Why is my pump running but not pumping water?
Why does my pump keep losing prime?
Why is my pump leaking between the pump and motor?
Why is my water pump making so much noise?
Common causes of pump noise include cavitation, worn bearings, and loose mounting. Cavitation sounds like gravel or marbles inside the pump and often means the pump is starving for water, from a clogged suction line, a low water level, or a suction lift that is too high. A grinding or squealing sound can point to worn motor or pump bearings, while rattling or humming vibration often comes from loose mounting bolts or misalignment. Banging when the pump shuts off is a common sign of water hammer, which can come from the piping layout or from a check valve that slams shut. If the noise is new or getting louder, have it checked before a small repair turns into a failed pump.
Why is my pump running but not pumping water?
On surface pumps (jet, sprinkler, and other pumps that sit above the water and draw it up through a suction line), a common cause is a lost prime, meaning the pump is full of air instead of water. Other common causes include a clogged strainer, foot valve or impeller, a closed valve on the suction or discharge side, a water level that has dropped below the pump intake, or a worn impeller. On three-phase motors, a pump running backwards will spin but move little or no water. Running a pump dry can damage the seal and impeller quickly, so shut it off and have a qualified technician find the cause.
Why does my pump keep losing prime?
Losing prime applies to surface pumps, which sit above the water source and lift water through a suction line. Submersible pumps sit in the water and don’t need priming. On a surface pump, a common cause is an air leak on the suction side or a failing foot valve or check valve. Even a small leak at a fitting, union or cracked suction pipe lets air in and lets water drain back to the source when the pump shuts off. A water level that drops too low, or a pump set too far above the water source, can also prevent it from holding prime.
Why is my pump leaking between the pump and motor?
Water leaking between the pump and motor commonly means the mechanical shaft seal has failed. The seal keeps water inside the pump where the motor shaft passes through, and it wears over time or fails quickly if the pump runs dry. Have it repaired promptly, because water that reaches the motor can ruin the bearings and windings and turn a seal job into a motor replacement. A leak can also come from a worn O-ring or gasket on the seal plate, which is a similar repair.
Pressure, Tanks and Cycling
What pressure should I set my captive air tank to?
Why is the pressure switch on my pump cycling so rapidly?
Why does my pump keep turning on and off?
Why is my pump not building enough pressure?
Why is my Jet Pump chattering upon initial start-up?
What pressure should I set my captive air tank to?
On a conventional pressure-switch system, set the tank’s air pre-charge 2 psi below the pump’s cut-in pressure. For a 30/50 pressure switch that means 28 psi, and for a 40/60 switch it means 38 psi. Check and adjust the pre-charge with the pump turned off and all water drained from the tank, using a standard tire gauge on the air valve at the top. Variable-speed and constant-pressure systems may require a different setting, so follow the manufacturer’s instructions for those systems. Checking the pre-charge once a year helps prevent rapid cycling and extends the life of the pump.
Why is the pressure switch on my pump cycling so rapidly?
On a conventional pressure-switch system, the pump turning on and off while water is being used is normal. Rapid cycling (very short runs, on and off every few seconds) commonly means the pressure tank is no longer doing its job. Common causes include a low air pre-charge, a ruptured bladder or diaphragm (a waterlogged tank), or a clogged pressure switch tube or fitting that reads pressure incorrectly. A tank that is too small for the pump can also cause it. Rapid cycling wears out the switch contacts and can overheat the motor, so it should be corrected quickly.
Why does my pump keep turning on and off?
On a conventional pressure-switch system, it’s normal for the pump to turn on and off while water is being used. If the pump turns on and off while no water is being used, the system is losing pressure somewhere. Common causes include a leak in the plumbing or irrigation lines, a running toilet, or a check valve that lets water drain back toward the pump. If it cycles on and off very quickly during use, a common cause is the pressure tank (see rapid cycling above). Turn off all fixtures and watch the pressure gauge: if it drops, there may be a leak or a failing check valve.
Why is my pump not building enough pressure?
Common causes of low pressure include a worn impeller or diffusers, a clog in the suction line or impeller, an air leak on the suction side, or a water level too low for the pump. Low voltage can also keep the motor from reaching full speed. In some cases the pump is simply undersized for the demand, or the pressure switch is set higher than the pump can reach. A pressure and flow check against the pump’s performance curve helps confirm which it is.
Why is my Jet Pump chattering upon initial start-up?
Chattering at start-up is commonly the pressure switch reacting to pressure pulses from the jet pump. The switch contacts flutter open and closed as the pressure surges, which causes the chattering sound and wears out the contacts. Start by checking the pressure switch location and the piping arrangement, since correcting those can stop the chatter. If the chatter continues and the system pumps clean water, a pulsation plug installed in the pressure switch fitting dampens those pulses and resolves the chatter in most cases we see. The plug has a very small opening that can clog with sand or debris, so it isn’t the right fix for sandy or dirty water. A low tank pre-charge or air trapped in the system can also make the chatter worse.
Motors, Power and Electrical
I checked power to my pump but nothing is happening, why?
Why is my motor humming but not starting?
Why does my pump keep tripping the breaker or overload?
How do I know if the problem is the pump or the motor?
How do you change the rotation on a motor?
What is a VFD?
I checked power to my pump but nothing is happening, why?
If power is reaching the system but the pump won’t start, the problem is often somewhere between the breaker and the motor. Common causes include a tripped motor overload, burned or stuck pressure switch contacts, a failed capacitor or control box (on many single-phase and submersible pumps), a broken wire, or a jammed pump. The motor itself may also have failed. Turn off the power and have a qualified technician evaluate the pump and motor rather than working on the equipment yourself.
Why is my motor humming but not starting?
A motor that hums but won’t turn is getting power but can’t start. Possible causes include a failed start capacitor or starting switch on single-phase motors, a jammed or seized pump, debris in the impeller, worn bearings, low voltage, or a three-phase motor that has lost one of its power legs. A jammed pump can cause humming just as a motor problem can, so the symptom alone doesn’t confirm which part has failed. Shut the power off right away, because a motor left humming can overheat, and have a qualified technician evaluate the equipment.
Why does my pump keep tripping the breaker or overload?
Repeated tripping commonly means the motor is drawing more current than it should or is overheating. Possible causes include a jammed or binding pump, shorted or grounded motor windings, a damaged power cable (especially on submersible pumps), a failing capacitor, low or unbalanced voltage, undersized wiring, or overheating from inadequate cooling or ventilation. A jammed pump can trip the breaker just as a motor problem can. Don’t keep resetting the breaker; have a qualified technician test the pump, motor and wiring before the motor is damaged.
How do I know if the problem is the pump or the motor?
Symptoms can point in a direction, but they don’t confirm a diagnosis. Humming without starting, tripping breakers or a burning smell can come from the motor, but a jammed pump can cause the same symptoms. Low flow, low pressure or leaking between the pump and motor more often point to the pump end. The reliable way to know is to have a qualified technician evaluate the equipment. For submersible pumps, electrical tests at the surface can often narrow it down before the pump is pulled. Our shop can test both the pump and the motor and tell you what needs repair.
How do you change the rotation on a motor?
Changing a motor’s rotation is electrical work, so have a qualified technician handle it. Three-phase motors can be changed at the power connections, while many single-phase pump motors are not reversible at all. Running a pump backwards reduces performance and can damage some pumps, so the technician should confirm the correct direction against the rotation arrow on the pump.
What is a VFD?
A VFD (variable frequency drive) is a controller that adjusts a motor’s speed by changing the frequency and voltage of the power it receives. On a pump, that lets the system deliver the flow or pressure needed instead of running at full speed all the time. On a properly selected and configured system, the benefits can include steadier water pressure, gentler starts, and potential energy savings, though results depend on the application and how the drive is set up. Some VFDs can also run a three-phase motor from single-phase power.
Sprinkler, Well and Septic Systems
Could I use my sprinkler pump to feed water to my house?
Do I need to use a check valve on my sprinkler pump?
Why does my well pump never stop running?
Why is the alarm on my septic system going off?
Could I use my sprinkler pump to feed water to my house?
We don’t recommend it without a proper evaluation. Sprinkler pumps usually draw from irrigation wells, lakes or canals, and that water isn’t treated or tested for drinking. A sprinkler pump also may not deliver the steady pressure and flow a household needs, and house service requires suitable components and controls, such as a pressure tank and pressure switch or constant-pressure controls. Connecting an irrigation supply to your home’s plumbing can also violate plumbing codes and risks contaminating the household water supply. If you need a well system for the house, we can help size the right pump, pressure tank and controls for that use.
Do I need to use a check valve on my sprinkler pump?
In most cases, yes. When the pump sits above the water source, a foot valve or check valve on the suction side keeps water in the line so the pump stays primed between cycles. A check valve also prevents water from draining back through the pump. Valve selection and installation matter: an appropriate check valve, installed correctly, can help control water hammer, but a check valve that slams shut can also cause it. Submersible well pumps typically have a check valve built in or installed in the drop pipe.
Why does my well pump never stop running?
A well pump that keeps running after water use has stopped either can’t reach the pressure switch’s shutoff setting or has a control problem. A very common cause in our area is debris from the well clogging the jet package, including the nozzle or venturi tube, which keeps the pump from building enough pressure to reach shutoff. Other common causes include a leak in the plumbing or a broken pipe in the well, a worn pump, a water level that has dropped, a clogged pressure switch sensing tube, or switch contacts that are stuck closed. If the pump keeps running when no water is being used, have it checked soon.
Why is the alarm on my septic system going off?
A common cause is a high water level in the pump tank or lift station, from a failed pump, a stuck or failed float switch, a tripped breaker, or more water entering the system than it can handle, such as during heavy rain. Some systems also alarm for aeration problems. Silencing the horn stops the noise but doesn’t correct the fault, and the alarm and controls should not be disconnected. Cut back on water use, check the breaker for the pump, and if the alarm doesn’t clear, call for service right away to prevent a backup. We offer 24/7 emergency service for sewage and lift station pumps.
Repair, Rebuild and Replacement
Should I repair or replace my pump?
Can my pump or motor be rebuilt instead of replaced?
Is it better to rewind a motor or replace it?
What information do you need from me to identify the correct replacement pump?
Should I repair or replace my pump?
It depends on the pump’s age, the repair cost compared to the total installed cost of a replacement (the new unit plus installation), how much downtime each option means, and whether parts are still available. Repair often makes sense for larger commercial and industrial pumps, or when the problem is a wear part like a seal, bearing or impeller. Replacement often makes more sense when the repair cost approaches the installed cost of a new pump, parts are discontinued, or a newer, more efficient model would lower operating costs. Because we both repair and sell pumps, we can give you an honest comparison of both options.
Can my pump or motor be rebuilt instead of replaced?
In many cases, yes. Our shop rebuilds and remanufactures pumps by replacing seals, bearings, impellers and wear rings, and machining parts back to factory specifications. Electric motors can be rewound, with new bearings installed and the motor tested before it goes back into service. Rebuilding is often the most cost-effective option for larger or hard-to-replace equipment.
Is it better to rewind a motor or replace it?
Rewinding usually makes the most sense for larger motors, specialty motors, or motors with long replacement lead times, where a rewind costs less than a new unit. Smaller standard motors are often cheaper to replace than to rewind. Other factors include the condition of the motor’s core, how quickly you need it back in service, and whether a new premium-efficiency motor would save on energy. We offer computerized rewinding in-house and can quote both options.
What information do you need from me to identify the correct replacement pump?
The fastest way is a clear photo of the nameplates on both the pump and the motor. Helpful details include:
- Brand, model number and serial number
- Horsepower, voltage, phase and RPM
- Required flow and pressure
- The liquid being pumped (clean water, well water, wastewater, pool water, etc.)
- What the pump is used for (well, irrigation, pool, sewage, booster, etc.)
- Inlet and outlet pipe sizes
- Photos of the pump as it’s installed
- For well pumps: well depth, pump setting depth, pipe size, and the pumping water level and available well yield when known
Matching horsepower alone doesn’t establish an equivalent replacement, since two pumps with the same horsepower can deliver very different flow and pressure. If the nameplate is missing or unreadable, our team can help identify the pump from photos and measurements.