Why does the submersible pump hum when operating, but does not pump water? Why do submersible pumps fail? Why does the fecal pump not work?

Reliable sewerage in a private house ensures maximum comfort for all residents. However, in some cases it can fail, becoming clogged with large particles or failing to process storm drains. In this case, drainage pumps are used, and therefore they must be maintained in good condition and ready.

Drainage self-priming equipment

Intensive operation of hydraulic devices can cause them to break. Users have to quickly repair clogged channels in devices, replace a burnt-out motor, or repair a water level float switch with their own hands. It is not always possible to do these operations correctly in a short time, so you need to worry about quality repairs in advance.

Design features of drainage pumps

A drainage water pump for pumping water uses its main element - an impeller - to build up pressure in the system. In addition to this, the design contains the following elements:

pump unit;
electric motor operating from a 220 V household network;
suction unit with filter element;
float circuit breaker.

Design

Since operating conditions imply the presence of liquid in contact with the housing, the outer part consists of tightly fitted parts of a composite housing. This ensures high-quality sealing, and the material for the housing is:

stainless steel with sufficient chromium alloying content;
moisture-resistant plastic.

During operation, it is necessary to protect the housing from mechanical damage so as not to depressurize the installation.

It is necessary to follow the manufacturer's operating recommendations so that the float pump for pumping out water works with liquid that contains contaminant particles of an acceptable fraction. The threshold geometric value is indicated in the device passport. Typically the permitted interval is 3-50 mm in diameter.

Industrial units can also work with large fractions. Improper operation of the pumps can lead to the electric motor humming, but not starting to return, or to other types of breakdowns.

Troubleshooting

In most cases, you can figure it out on your own. To do this you will need a set of wrenches, screwdrivers, pliers, a multimeter and possibly a soldering iron. In some cases, you will have to use the repair kit provided by the manufacturer.

VIDEO: Drainage pump. disassembly and repair

Mechanical breakdowns

In cases where the electric motor hums but does not rotate, the cause most often lies in a mechanical fault.

It is worth checking the integrity of all blades. A broken piece can block the rotation of the head shaft located in the housing.
Blocking of rotation, which causes a characteristic hum, is caused by a damaged bearing assembly on the shaft. Under the influence of wear, it worsens the alignment and leads to the shaft stopping.

To check for these reasons you need to:

turn off the power supply;
remove the pump from the water and place it on a level surface;
try to rotate the working impeller by hand, visually checking its integrity.

If there is difficulty, the unit must be replaced or repaired, because if the electric motor does not start pumping, but hums, then the problem is often not with the electrician, but with blocking the rotation.

Reduced water level

Drainage equipment in most models has a submersible design. Due to this, it is possible to effectively pump out liquid. Operation without liquid inside the working cavities of such pumps leads to rapid failure of the units. An important factor in protecting against operation without water is a special device - a float switch.

This is what a pump looks like when it has been running for a long time and is not completely immersed in liquid.

The part is capable of blocking the operation of the entire pump in time if the liquid level drops below a critical level for the device. The role of a kind of gyroscope is performed by a metal ball that changes its position depending on the location of the unit in the water. It acts on the lever, closing/opening electrical contacts.

Air valve malfunctions

Some drainage models have a special bleed valve. The accumulated air bubbles are passed through it. Many pollutants are dissolved in the problematic liquid media that the pump pumps. They are able to envelop the surface of the ball from the valve and due to this it can fill in its seat.

If the system does not provide constant air venting, then your Karcher will hum, but will not pump water. You can restore functionality after pumping a certain volume of clean water. The system will flush itself, and the liquid will remove contaminants from the ball.

Electric motor failure

The pump can become silent during operation and not respond to the supply of electricity. In many cases, this is due not so much to problems with the cable, which can fray or bend, but rather to an interturn short circuit:

In such a situation, the characteristic smell of burnt wire insulation will be heard from the electric motor.
The second sign will be significant overheating of the unit, which can be heard by touching the switched off unit with your hand.

The reason for such malfunctions is the lack of idle protection. Significant overheating of the motor leads to heating of the turns, and they, melting the insulation, form an electrical short circuit between the turns.

Cleaning the pump

Operation can only be restored by replacing the block or rewinding the wire in the damaged area. The second option may be a little cheaper, but if performed poorly, it can soon lead to new malfunctions.

Do-it-yourself pump repair

In most cases, doing repairs yourself comes down to eliminating mechanical damage. The most popular types of repairs are replacing the impeller or bearing units.

To completely disassemble the device, a special set of tools is required. The case is opened when completely disconnected from the power supply and on a dry apparatus. In most cases, repairs are entrusted to experienced specialists.

VIDEO: Features of equipment repair

In private households, a drainage pump performs many useful functions, including pumping water from wells, swimming pools, sewage basins and flooded basements. Responsible owners try to adhere to the rules for operating the drainage system in order to ensure its uninterrupted operation and not be left without a much-needed device at the most inopportune moment. However, even in this case, no one is immune from unexpected problems. The situation when the drainage pump hums but does not pump water is one of the most common. Moreover, the complexity and speed of eliminating such a malfunction depends on its cause and knowledge of the device.

Drainage pump device
Insufficient water level
Mechanical failure
Air valve problems

Is it possible to fix a problem with the pump yourself Video: repairing a drainage pump Design of a drainage pump

Without delving too deeply into the details of the design, the main components of a typical drainage system are:

engine;
pump unit;
suction grid;
float switch.

Drain pump design

Taking into account the operating conditions of such equipment, its body is made of stainless steel or wear-resistant plastic. An impeller is installed on the motor shaft, due to the rotation of which a suction effect is created.

For your information. Since the pump is immersed in water, manufacturers pay special attention to waterproofing the housing to prevent damage to the electrical part inside the device.

Depending on the size of the suction grid openings, the maximum size of solid particles is determined, the presence of which is allowed in the pumped water. In different models, this parameter ranges from 3 mm to 50 mm (in some cases up to 120 mm).

The drainage pump does not pump water: the main reasons

There may be several reasons why the drainage pump hums but does not work, that is, does not pump out water.

Insufficient water level

Since drainers are submersible pumping equipment, they must be located in an aquatic environment. To prevent the pump from operating in dry running mode, special protection is installed on this device - a float switch that turns off the device if the water level in the source is insufficient.

Interesting to know. Inside the float switch is a ball that changes its position depending on the water level, closing or opening the contacts of the electrical circuit.

There are situations when the engine is running, but the fluid is not pumped out. As a rule, this is due to the cavitation mode - as a result of too much power of the device, water simply does not have time to penetrate between the impeller blades. In this case, the pump must be immersed deeper.

Float switch device

Mechanical failure

If the sump pump hums but does not turn, then the problem is most likely caused by a mechanical problem. If the impeller blades are damaged, the broken part may cause the shaft to become wedged. Another reason for shaft jamming is the loss of functionality of the bearing system.

It's quite easy to check. It is necessary to remove the device from the water, having first disconnected it from the power supply, and try to turn the impeller by hand. If rotation is difficult, additional disassembly of the device will be required.

Interturn short circuit of the electric motor

In addition to a mechanical problem, the engine not spinning can be caused by an electrical problem. If the drain pump makes a loud noise when turned on, and the power cable begins to overheat, then the most likely cause is an interturn short circuit in the motor winding.

This is one of the most common problems with drains in the absence of protection against dry running. During operation of a submersible pump, heat is removed from the electric motor using water, while during idling the motor overheats, which causes a breakdown in the insulation of its windings and loss of functionality.

Sometimes a burnt out motor winding can be seen with the naked eye.

Air valve problems

Some sump pump models are equipped with a special air release valve. Due to operation in a difficult environment, water with various impurities gets inside the device, which over time causes the ball located in the valve hole to stick. If there is no constant air removal, the pump stops pumping out water and operates in idle mode.

Advice. To restore the functionality of the drain system, sometimes it is enough to bleed the pump in clean water, which will help clear the valve hole of excess deposits.

Is it possible to fix the problem with the pump yourself?

The desire of any owner to solve the problem of pumping water without involving specialists is quite natural. However, this is not always possible, especially if we are talking about serious malfunctions with the mechanical or electrical part of the device.

If the drainage pump hums but does not pump water when the liquid level is low, this situation is described in almost any operating manual for this equipment. If possible, the pump part must be lowered deeper or the remaining water must be removed manually.

If the shaft is wedged, you cannot do without disassembling the device. Here you will need a special tool and certain skills in repairing such devices. A mechanical problem can often be resolved by replacing the impeller or bearings. With the electrical part, everything is much more complicated, since a burnt-out motor needs rewinding, which can only be done in the factory.

The performance of a drainage pump largely depends on its correct placement and compliance of the quality of the pumped water with the capabilities of the device.

Before disassembling the device, you should realistically evaluate your knowledge and skills. Unprofessional repairs often lead to the impossibility of restoring the functionality of the equipment. Therefore, if the drainage pump hums but does not rotate, it is better to involve specialists and save yourself from the need to purchase a new device.

Video: drain pump repair

A good manager of a summer cottage or the owner of a private house has at least one encountered the problem of pumping out water. Such a nuisance could occur as a result of flooding of basements after heavy rains or melting snow, the need to pump water from a swimming pool in a country house or a private house, a well or a sewer sump.

For these purposes you will need a drainage pump. Responsible owners of such equipment try to monitor the technical condition and timely repair the drainage pump in order to avoid breakdowns of the pumping unit at the wrong time and so that it can turn on as it should.

Drainage pump: purpose

By drainage we mean a pump that is designed to pump out (drainage) any liquid or ensure the operation of the sewage system in normal mode. A drainage pump is often confused with a fecal pump. This happens out of ignorance. After all, with the same operating principle and purpose, they are similar, but the liquids they pump are different.

Drainage pump Gardena classic

The use of a fecal pump is possible for pumping out liquids with impurities with a diameter of up to 8 mm. To prevent excess impurities from entering the working chamber, a grinder is installed. The ability to crush and remove 98% of debris allows for extremely rare repairs of the unit.

The drainage pump does not have a grinder in its design. For protective purposes, it is equipped with a mesh filter, which collects larger particles of impurities up to 10 mm in size. The operation of the drainage pump is carried out by supplying liquid using an impeller, as well as other elements of the system. After this, the liquid that was pumped from a container or water source enters the hose. The freed space inside the housing is occupied by new liquid, which comes from the inlet.
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Major breakdowns and malfunctions of drainage pumps

Let's look at the main problems associated with repairing a drainage pump and which occur most often:

the pump hums, but it does not pump water;
when the unit is turned on, the circuit breaker is knocked out or plugs fly out;
strong vibration or overheating;
low fluid pressure at the outlet;
breakdown of the pressure switch or hydraulic accumulator;
defrosting the unit.

The pump hums without creating fluid pressure

A common problem occurs when the drain pump does not pump, but continues to hum. In this case, little or no fluid pressure may be created.

Drainage pump device

The most common reasons why the pump hums but does not pump water are:

low level of pumped liquid;
interturn short circuit of the electric motor;
mechanical failure;
problems with the air valve.

The location of the drainage pump in the aquatic environment is mandatory, since they are considered submersible pumping equipment. To prevent the use of the drainage unit without liquid (dry), additional protection is installed on it in the form of a float switch. The float switch is capable of automatically turning off the unit if there is insufficient level of the pumped liquid.

This shutdown is possible thanks to a ball located inside the float. When the water level changes, it changes location in the float and closes or opens contacts in the electrical circuit. Sometimes it happens that the engine hums or runs, but no fluid is pumped. This is due to the cavitation regime. Cavitation occurs if the equipment has excessive power, and therefore water does not always have time to seep through the impeller blades. To solve this situation, the pump should be lowered deeper.

The lack of movement of the electric motor may be due to an interturn short circuit. This electrical failure can be detected by turning on the engine and it will begin to hum, and at the same time the power cable will heat up. Turn-to-turn short circuits mainly occur due to equipment operating in a dry environment. After all, the engine is cooled by pumped water. Without water, the engine idles and overheats, which causes damage to the insulation of its windings.

Burnt out pump winding

A mechanical fault occurs when the engine is running. If it turns on, but does not spin and hums. This can happen if the impeller blades break. Broken parts can jam the rotating shaft. Or, if the shaft jams, the functionality of the bearing system may be impaired.

All this, with such long-term operation, will still lead to an interturn short circuit and then the drainage pump will have to be repaired. In order to verify this failure, you will need to turn off the power and remove the equipment from the aquatic environment. After this, you need to rotate the impeller on the shaft. If you cannot turn the impeller, you will have to disassemble the device.

Some drainage pumps have special valves installed that release air. The ball located in the valve often sticks. This happens when the device operates in a difficult environment and water with impurities gets into the inside of the unit. Sticking of the ball disrupts the constant removal of accumulated air and the engine starts to idle. To restore functionality, sometimes it is enough to let the pump run in clean water. The valve hole is slightly cleaned of adhering dirt and plaque.

When the electric motor is turned on, the circuit breaker may turn off or the fuses on the plugs may blow and the cable feeding the pump may melt. This occurs when the shaft jams in the bearings or when the electric motor burns out. If the electric motor burns out, a characteristic burning smell will be heard.

Float switch repair

This could happen when the device was connected incorrectly, the wrong power supply was selected - 380 V instead of 220 V. It is better not to disassemble the pump in this case, since you will still have to take the drainage pump for repair to a service workshop for further rewinding armature windings. To confirm that the windings are faulty, you can measure their insulation resistance.

The minimum insulation resistance to enable the unit to operate must be 0.2 MOhm.

As mentioned above, some models of drainers are equipped with thermal relays that turn off the device if it overheats. In its absence, you have to carefully ensure that the pump is not in working condition for a long time outside the pumped liquid. During prolonged operation in a dry case, the device will overheat, which will entail displacement of the magnet fixed with epoxy glue, which, in turn, The pump piston may jam.

After the magnet peels off, internal vibration may begin and a chain reaction about the pump will occur, which ultimately destroys all mechanics and electronics. As a result, the entire apparatus becomes a pile of scrap metal. Experts believe that in most cases, after such breakdowns, repairs for the drainage pump will not be economically profitable.

If this defect is detected in a timely manner, you should contact the service center. There they will carry out appropriate diagnostics of the equipment, replace damaged parts and install the magnet itself in place. Self-repair may lead to a series of incorrect actions, which will affect performance.

Gilex pump repair

First, the device is completely disassembled and the magnet is carefully removed. After this, apply longitudinal notches to the body and magnet for better adhesion. After that, glass sealant or new epoxy glue is applied, worn parts are replaced and the pump is reassembled in the reverse order.

Drains, both surface and submersible, break down in the form of low pressure at the outlet. There are several reasons for this failure:

The most common filter that gets clogged is the filter. The pressure of the pumped liquid through the sleeve (hose) may drop sharply or stop completely. The main symptoms of this are overheating of the motor or overloaded operation of the device and its strong noise. In surface stations, when worn, the sleeve is damaged or the clamp that tightens the mount on the sleeve is weakened.

This allows unnecessary air to be sucked into the pumping system and the ability to lift water from the source is lost. The solution to this problem is simple- you will need to inspect all connections on pipes and clamps.

Sometimes everything seems fine. In this case, the vibrator may have a small stroke. To eliminate this malfunction, the device is disassembled and an additional washer and vibration rod are adjusted. Lining one washer does not always help. Several more of the same may be required, which is determined by the selection method. Seals and membranes must be intact and without damage.
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Drain pump repair (video)

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Repair of drainage pumps

The faults listed above for the drainage pump cannot always be corrected on your own. You can independently fix a weakened shock absorber, release or replace the float, eliminate mechanical damage that resulted in jamming of the impeller, and replace the power cable.

The simplest of all this will be securing the shock absorber. To do this, you will need to disassemble the device body and tighten the loose nuts on the mounting bolts. It is imperative to lock the top nut to prevent further loosening. It will take some time to replace the power cable. Replacing the condenser is possible in some drainage models.

Other faults are practically impossible to eliminate without the involvement of service workshops. For example, if a rod is broken, it is easier and sometimes cheaper to purchase new equipment than to disassemble it and try to repair it. Replacing a valve is a difficult and unprofitable undertaking to solve the problem on your own. Replacement of a burnt winding should be carried out in specialized workshops.

Disassembling the Belamos DWP CS drainage pump

to menu The most common causes of breakdowns

If there is a need to repair pumping equipment, it is necessary to find out the probable cause of its failure, which are often:

Failure to comply with the terms of periodic inspection and repair of equipment.
The equipment was not operated correctly. During operation of the device, its operating parameters were exceeded.
The pumped liquid contains solid impurities larger than required.
Long-term use of the pump in dry mode.
The equipment was installed incorrectly or poorly.
The hydraulic accumulator and relay are out of order, and there is no filter.

When the first hint of a breakdown appears, you should immediately check the following components of the device:
The ideal distance between the electromagnetic coils and the piston should be set from 0.4 to 0.5 cm. If these distances are not observed, the coils will beat if the gap is too large and the motor will overheat if the gap is too small.

Draining a reservoir with a drainage pump

The piston must not have mechanical damage or defects, its condition must be elastic. The valve covering the inlet holes must have a gap between the body of 0.7 to 0.8 mm. Air should flow freely when blowing on the intake side. It often happens that poor pump performance is not due to its failure. There may be power outages in the network.

Therefore, before you begin disassembling the device, make sure that the mains voltage matches, which should be 220-240 V. It should be noted that for long-term and reliable operation of the pumping equipment, it is necessary to carry out timely technical inspection and maintenance of the device and follow the rules of technical operation.

Registration: 06/24/08 Messages: 72 Thanks: 1

There is a drainage pump in the cesspool. It's been working fine for two years now. I used it to pump out water (when the hole was filled, I pumped out the water, then turned it off). The other day I turned on the pump again, but the water was not pumped out. I went and looked at the hose - no water was coming out of it at all. I turned off the pump, took out any damage from the hole, and found no breaks (kinks) in the hose. Everything looks fine, but it doesn't work. The pump is equipped with a float switch.
What could be the problem? Experts, please tell me.

Two ideas and two questions arose.

1. Maybe the pump has overheating protection and that’s why it doesn’t turn on? After all, it’s hot outside (in the sun + 40 or more) and we’re pouring hot water into the pit.
2. Could the problem be with the float switch?
1. How does the float switch work (when it is above the pump, it turns the pump on, when below it turns it off, one way or another; or does it depend on the presence/absence of water)?
2. Could the pump burn out due to idling?
Registration: 04/27/07 Messages: 215 Thanks: 35
Registration: 06/24/08 Messages: 72 Thanks: 1

answers to questions - a ball is rolling in the switch... lifted - the ball fell on the contacts.
To check, place it in a bucket of water and lift the float up. if it buzzes, then it works - if not, then look further along the circuit... there is no protection against overheating there... but the engine is cooled by pumping water... incl. if you believe your words, you just burned it...

Thanks for your response.

Could something happen to the contacts (ball)?
Where next to look “along the chain”?
How could I burn him? He was always in my hole with water.
Bandit_r
Why did you decide that there is no protection against overheating?
I have a drainage pump from ALKO and the instructions say that there is overheating protection.
avn1
Registration: 06/24/08 Messages: 72 Thanks: 1

avn1
Lower the pump into the water so that the float floats up and shake it... sometimes this float does not work. If it does not work, only opening it will help.

I'll try to shake it.
What should you look at when opening it?
Registration: 11/19/08 Messages: 114 Thanks: 41
Registration: 06/24/08 Messages: 72 Thanks: 1

I tried shaking it, but nothing worked. And I turned it on in the bucket too - nothing. It doesn't even buzz.

I'll take it apart (even though I'm not an expert in this). Is it really possible to get to the blades without disassembling the pump? In my pump they seem to be out of reach.
Registration: 11/19/08 Messages: 114 Thanks: 41

Usually, drainage drains have a shaft with blades directly visible from below. I can see it. It was specially done this way so that it could be cleaned if something gets sucked in there.
Registration: 06/24/08 Messages: 72 Thanks: 1

I have a similar pump
the blades are invisible
avn1! I believe that if you are not familiar with the structure of the drainage system, do not try to restore it yourself, but rather contact a service center. Perhaps its windings burned out when water got inside.
Registration: 06/24/08 Messages: 72 Thanks: 1

I couldn’t find the service, so I decided to open it myself. As it turned out, the engine hums, but does not turn over. The float switch is OK. I tried to rotate the shaft - it seemed to be spinning normally. I turned the pump back on and it hums, but doesn’t turn. I immediately pushed the shaft and it started spinning! I did this several times, after which it started to run on its own. Thanks everyone for your help.
However, after assembly the following questions arose.

On the end of the pump there is something like a six-octagonal plastic cover (the size of a nickel), and in the middle there is a hole through which water flows in (the bulbs are visible). Should this be the case? Maybe he can fix her?

The same bulbs became visible at the junction between the pump housing and the power cable and float switch. Maybe the joints should also be siliconized to prevent water from getting in? Or is it not scary?

Please answer urgently, water is already flowing from the hole, it needs to be pumped out, but I don’t want to burn the pump.
Registration: 03/24/09 Messages: 39,655 Thanks: 29,262

Hello avn1! Sorry, I personally have not had to deal with drainage pump repairs. IMHO, I think it’s better to silicone the joints.
Registration: 06/24/08 Messages: 72 Thanks: 1

Thank you, Andrey. That's what I'll do.
Registration: 06/09/11 Messages: 113 Thanks: 5

I have this problem... I have a Gilex 200/10 F drainage pump. I pump it with almost clean water from about a meter deep. the problem is that when you turn it on... the motor starts to work, but the water does not flow... because it weighs on a rope, I pull it several times and it doesn’t immediately, but it starts to pump. a visual inspection revealed nothing. the suction part is clean, nothing is clogged and everything at the outlet is clean.

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Any malfunction of the water supply system at home is the result of an error by the organization or individual involved in its implementation. In this case, the homeowner has a good chance to learn from his mistakes by repairing the electric pump with his own hands and, with a “successful” set of circumstances, improve his health by carrying water manually for some time from the nearest water source.

Rice. 1 Well pump assembled

Troubleshooting algorithm

This sequence of actions applies to all types of pumping equipment, regardless of the location and method of installation. It should be noted that the power supply system of the pump, apart from the wires switched by switches, does not have complex circuits, so if the submersible water pump does not pump water, but starts and hums, problems with the supply of the required supply voltage in the vast majority of cases can be eliminated.

If the drainage pump or well model does not pump water, it may not start if the built-in or external condenser malfunctions and will require repair and replacement.

First of all, repair of electric pumps should begin by turning off the supply voltage, removing it from the water intake source and disconnecting the outlet hose.

When reconnected, the reasons why the pump does not work can be divided into several areas according to the location of the manifestation - we will consider them below.

Rice. 2 Water supply scheme for a private house

Malfunctions of pump protection systems

Typically, a properly assembled water supply system and high-quality pumps have devices that prevent them from operating in idle mode.

In the event of a malfunction of such protective devices: the well dry running relay and the float switches of the drains, well or sewage pump, the devices can operate in the absence of water.

Sometimes the float switch of well or drainage pumps, due to improper installation, does not fall along with a drop in the water level (it falls on a hillock or clings to a protruding object) - this leads to the electric pump operating in idling mode and its further failure.

Rice. 3 Popular Gilex pump with float switch

Vibration pumps, which usually do not have external protective devices connected to the system, operating for a long time without water after its level drops, can fail in the absence of built-in thermal protection.

Depressurization or breakage of the water main

The malfunction will help to identify the removal of the deep pump from the water intake source and connection to the supply voltage on the surface. If the pump, lowered into the water for testing, pumps water with the required pressure, then you should look for a leak at the place where the hose is connected to the outlet pipe or in the pipes that are laid underground for regular water supply at home (in a house, a leak can be easily noticed by the presence of water on the floor in a room with pumping equipment).

Mismatch between pump parameters and water intake source

During the dry season or with a sharp increase in water consumption, a situation may occur when the well or well does not have time to fill (the flow rate of the source is too low for normal operation of the pumping equipment). In this case, the electric pump will operate in dry running mode for some time in the absence of a similar relay or float switch in the system.

Clogged water intake system

A very common reason for the lack of water when the pump is running. Similar malfunctions can occur during the installation of pumping equipment: dirt and foreign objects can penetrate into the pipes. During operation, the screens and replaceable filter cartridges become clogged.

Fig.4 Clogged electric pump disassembled

The filters and impeller of the impeller of submersible devices need regular cleaning during operation - if this does not happen, over time they become clogged and the operating pump hums, but does not pump water or does so with low pressure.

A situation often occurs when the pump actuator stops completely when clogged - the impeller does not rotate, and the vibration pump piston does not move. A clogged well or drainage pump removed from a water intake tank does not pump water when turned on superficially - do-it-yourself repairs will require disassembly and further cleaning of the device mechanism.

The pump has failed

The biggest problem that can happen to an electric pump is the burnout of the winding, and the device usually cannot be repaired (rewinding the winding with your own hands is difficult, and in a workshop the cost of work and materials will not be comparable to the price of the electric pump).

With this malfunction, the electric pump will hum, but will not be able to pump water.

Fig.5 Vibration pumps under repair

Sometimes the impeller of borehole and well pumps may break, the check valve system may fail (they will not allow water to pass through) and the piston ring of vibration models may fail.

Due to constant vibrations during operation, vibration pumps are subject to loosening and unwinding of the mounting mechanism of the composite body, the fixing nuts of the check valve and the piston. These factors can lead to the loss of functionality of a working electric pump, which will hum but not pump water.

Violation of the operating rules for submersible pumps, errors in the installation of the water supply system, a sharp increase in water intake and a decrease in the flow rate of a well or borehole can lead to the hum of a working electric pump, in which water will not flow to the consumer. In most cases, you can repair electric pumps yourself if you remove the device to the surface to accurately determine the problem area.

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1 Drainage pump: purpose

1.1 Main breakdowns and malfunctions of drainage pumps

Let's look at the main problems associated with repairing a drainage pump and which occur most often:

the pump hums, but it does not pump water;
when the unit is turned on, the circuit breaker is knocked out or plugs fly out;
strong vibration or overheating;
low fluid pressure at the outlet;
breakdown of the pressure switch or hydraulic accumulator;
defrosting the unit.

1.2 The pump hums without creating fluid pressure

A common problem occurs when the drain pump does not pump, but continues to hum. In this case, little or no fluid pressure may be created.

The most common reasons why the pump hums but does not pump water are:

low level of pumped liquid;
interturn short circuit of the electric motor;
mechanical failure;
problems with the air valve.

The minimum insulation resistance to enable the unit to operate must be 0.2 MOhm.

Drains, both surface and submersible, break down in the form of low pressure at the outlet. There are several reasons for this failure:

1.3 Repairing the drainage pump (video)

2 Repair of drainage pumps

2.1 The most common causes of breakdowns

If there is a need to repair pumping equipment, it is necessary to find out the probable cause of its failure, which are often:

Failure to comply with the terms of periodic inspection and repair of equipment.
The equipment was not operated correctly. During operation of the device, its operating parameters were exceeded.
The pumped liquid contains solid impurities larger than required.
Long-term use of the pump in dry mode.
The equipment was installed incorrectly or poorly.
The hydraulic accumulator and relay are out of order, and there is no filter.

The variety of designs and operating conditions of pumps determines the variety of possible malfunctions. The instruction manual for each pump contains a detailed list of common faults and how to resolve them.

Here is a brief overview of typical pumping equipment failures.

The main signs of malfunctions that appear during operation: vibration of the unit, increased noise levels and changes in its tone, increased operating currents, pressure pulsations.

The reasons for pump failure can be divided into several groups.

1. Mechanical faults:

1.1. defects in manufacturing, assembly and installation of the pumping unit;

1.2. caused by wear and tear of the pump unit.

2. Control system malfunctions:

2.1. work in unacceptable modes (outside the working area);

2.2. malfunction of the power supply system;

2.3. electric motor malfunction.

3. Hydraulic system malfunctions:

3.1. incorrect selection of pump;

3.2. changing network parameters.

4.1. Mechanical problems

Manufacturing or assembly defects are identified during pre-launch preparation and during test run. Some factory defects appear only after some time of operation.

During operation, wear occurs on bearings, impellers or rotors, seals, and rubber coupling parts. Chemical pumps also have corrosion in the flow part.

Bearing wear leads to increased vibration of the unit. Long-term operation on worn bearings may result in rotor misalignment. The consequences are an increase in power consumption, increased heating of the bearings and strut, interference with the impeller housing, misalignment and interference with the oil seal housing.

Wear of the impellers leads to a drop in flow and pressure with virtually unchanged power consumption. If the wheel and throat seal at the inlet are severely worn, the balancing is disrupted: an unbalanced axial force occurs. The consequences are the load on the bearings and their wear, displacement of the impeller in the pump cavity, its friction against the housing (suction pipe) and wear of the wheel and housing.

Wear of mechanical seals is especially dangerous for submersible pumps (GNOM, NPK, TsMK...), since water enters the cavity of the electric motor and causes damage to the winding.

The main malfunctions and their causes are given in the table:

Symptoms of faults	Causes of malfunctions
Symptoms of faults	Manufacturing defects, assemblies	Depreciation of equipment, violation of operating rules
The pump does not produce the stated flow and pressure	The dimensions of the impeller or the tolerances when installing it are not maintained	Impeller wear, impeller displacement
The volumetric pump does not produce the stated flow and pressure	Clogged valves	Wear of seals and valves
Increased power consumption	Misalignment of the unit	Oil seal constriction, impeller wear
Overheating of bearings	Misalignment of the unit, incorrect installation of bearings	Improper lubrication of bearings, bearing wear
Leakage on the pump shaft	The manufacturing tolerances of the stuffing box seal are not met. Poor quality cuffs	Wear of the stuffing box, mechanical seal wear
Increased vibration	Misalignment of the unit, insufficient frame rigidity or foundation Unbalanced rotor or coupling	Bearing wear cavitation, failure to tighten the screw connections of the pump or motor
Rotor jam	The required “run-up” of the rotor in multi-stage pumps is not ensured	Exceeding the permissible temperature of the pumped liquid Particulate matter ingress

4.2. Operation in unacceptable modes

For all pumps, running “dry” (without filling the pump cavity with liquid) is unacceptable.

This is especially dangerous for submersible pumps (ETsV, GNOM, NPK, etc.), because Engine cooling is disrupted and further insulation destruction occurs. Running dry leads to overheating and damage to the seals. The packing in the stuffing box wears out and then the protective sleeve is damaged. The rings in the mechanical seal are destroyed. A number of pumps (ETsV, UPS, HCM) have destroyed sliding bearings, which under normal conditions are lubricated and cooled by the pumped liquid.

To protect against dry running, it is necessary to install a dry-running sensor or an inlet pressure sensor, and install current protection (against operation with a current less than the rated one).

In some cases, if there is a possibility of dry operation, it is possible to use centrifugal pumps with double seals (with a barrier fluid supply).

For dynamic pumps, an unacceptable mode is also going beyond the working area (flow less than Q min or more than Q max), because this increases the likelihood of cavitation. Working with a feed greater than the maximum also leads to overload of the electric motor.

4.3. Power system malfunctions

Here, two groups of faults are distinguished: deviations of network parameters from the nominal ones and faults associated with connecting wires.

When the network voltage is low, the electric motor does not develop its rated power, and when starting the pump, the parameters may be disrupted. Voltage fluctuations and surges, phase imbalance (voltage inequality in different phases) lead to fluctuations in rotation speed, increased vibration of the electric motor and, in the worst case, to breakdown of the winding insulation.

The main faults associated with connecting wires are incorrect cable selection (increased resistance), phase loss, incorrect phase rotation (motor reverse).

With increased cable resistance, a picture may be observed as with a reduced supply voltage. As a rule, the cable becomes very hot, which can lead to damage to the insulation and a short circuit.

When a phase is lost, the motor continues to operate, but at the same time the currents of the motor windings increase sharply. If the protection does not work in this case, the result is overheating and destruction of the winding insulation.

The direction of rotation of a three-phase electric motor is determined by the phase rotation. With the opposite direction of rotation, a significant decrease in the parameters of centrifugal pumps and strong heating are observed. For vortex pumps (VKS, SVN) and gear pumps, the direction of fluid flow changes - from the pressure pipe to the suction pipe.

For stationary pumps, the direction of rotation of the electric motor is determined during installation and can only change when working on the electrical network. The direction of rotation of portable pumps (GNOM, NPK. ANS....) must be checked each time they are connected.