Repair of the pump "Gnome": an overview of popular breakdowns and how to eliminate them
With proper operation, the pump "Dwarf" can serve its owner for more than a decade. And even if the breakdown happened, you should not rush to replace it with another unit or call a specialist repairman.
Most of the malfunctions can be fixed by yourself, because the repair of the “Dwarf” pump is not difficult if you know the cause of the problem and how to fix the malfunction.
General information about the pumps "Gnome"
Pumps "Gnome" for pumping clean and dirty water is very often used by summer residents and owners of country houses. These are reliable and durable electric pumps that do not require complicated and expensive maintenance.
Under this brand are produced centrifugal submersible pumps with different technical characteristics:
- performance from 7 to 200 m3/hour;
- nominal head from 7 to 50 m;
- electric motor power from 0.6 to 21 kW.
In everyday life, the models “Mini Dwarf”, “Dwarf 16-16T”, “Dwarf 10-10T” and “Dwarf 20-25” are most often used, therefore we will continue to talk about these household electric pumps. These models are small in size, and their weight ranges from 10 to 32 kg.
Portable Gnome centrifugal pumps have a monoblock design and are used to pump clean and dirty water having a density of up to 1100 kg / m3 and containing solid mechanical particles up to 5 mm in size in an amount not exceeding 10%. The maximum density of solid particles is 2500 kg / m3.
Pumps are used to supply water from open reservoirs, wells, wells. Used to drain pits and trenches, for irrigation of agricultural crops, pumping groundwater from flooded rooms. The temperature of the pumped water for ordinary models is up to 35º С, models “Т” is up to 60º С.
Gnome centrifugal submersible pumps have a simple construction and consist of the following main parts:
- An electric motor that includes a stator, a bearing shield and a rotor.
- Pump unit, with impeller located on the rotor shaft, with intake net and outlet.
- Sealing system for protection against water ingress.
- The body of metal, cast iron or plastic.
- Power cable.
The motor is cooled by the external environment and oil, which is located in a special oil chamber of the electric motor. Oil also has the function of lubricating rubbing parts. The rotational speed of the rotor and the impeller is 3000 revolutions per minute. During rotation, a centrifugal force is formed, which pushes water through the discharge port.
Water enters the pump through a filter screen, which retains large particles. Then the water moves along the channels to the outlet, from which it enters the outlet branch pipe. The start of the electric pump is carried out by the starting device, which is connected to the power cord. The “Gnome” electric pumps have a capacitor and a circuit breaker that protects the electric motor from overload.
Pumps "Dwarf" refer to the submersible type, so they start only after a full immersion in water. The exception is the "Dwarf" electric pumps with a "cooling jacket". Most electric pumps are equipped with a float switch, which is mounted on the handle of the unit and provides a minimum suction height of 15 cm.
Typical causes of failure
According to statistics, 95% of cases of failure of the “Dwarf” pumps are associated with improper operation and installation. The most common causes of faults:
No. 1. Incorrectly selected motor protection circuit breaker.
An improperly installed and installed circuit breaker does not respond to critical voltages in the power grid. To protect the motor, you need to install a special machine, which is purchased separately.
The type of protective device is recommended by the pump manufacturer in the instruction manual. According to the manufacturer's recommendations, for example, for an electric pump of the “Gnome” brand, the use of the BA 101-3 automatic machine is mandatory. You can also use automatic machine ABB series MS.
№ 2. Thermal protection winding insulation melting
Thermal protection is built into the winding and when the motor is heated, it turns off its power. If the pump often overheats for some reason, then each time the insulation melts. This is an irreversible process that can lead to a short circuit and inevitable breakdown of the electric motor.
№ 3. The work of the electric pump without water
One of the most common causes of faults. The work of the submersible electric pump "Gnome" without the "cooling jacket" on dry should not exceed 15 minutes. Also, you can not use the pump for pumping high temperature water (over + 35º С for ordinary and + 60º С for “T” models). In both cases, the pump quickly overheats and fails.
No. 4. Use of a pump outside the operating ranges.
The pressure and productivity given out by the electric pump should not exceed the parameters specified in the passport.If the equipment operates with a significant excess of technical characteristics, the operating current on the motor windings significantly increases, which leads to its overheating. For a long time the pump will not be able to work with overload and will quickly fail.
No. 5. Pump operation on a valve or narrow pipe
Saving on pipes and their purchase of a smaller diameter leads to a decrease in the performance of the electric pump, i.e. He begins to work outside his working range. In this case, a very narrow pipe can become clogged, which will also lead to an enormous load on the pump. To avoid this it is necessary to use pipes of the appropriate diameter.
№ 6. Pumping unsuitable liquids
Such liquids include all liquids that are not designed pump "Gnome":
- chemically aggressive;
- highly abrasive;
- with particles of more than 5 mm and a density of more than 2.5 thousand kg / m3;
- viscous, with sediment, high temperature, etc.
Transfer of such liquids leads to breakage of many parts of the pump: from the screen filter to the electric motor, therefore it is strictly prohibited to use “Dwarf” electric pumps for faecal drains, chemical reagents, sludge!
№ 7. Frequent on / off of the pump
When starting the pump, it simultaneously consumes a large amount of electricity than later with uniform operation. This leads to the melting of the windings, and then to overheating of the electric motor. If the pump is in the well, then with frequent drops in the water level, the pump may automatically turn off and then turn on. This significantly reduces its working life. For such wells, with differences in water level, surface pumps are more suitable.
№ 8. Power surges in the mains.
With a voltage deviation of more than 5-10%, the operating current in the motor windings significantly increases, which leads to overheating. This may be due to unstable power supply or when using a cable of the wrong cross section. In the first case, the acquisition of a voltage regulator will help, in the second - the selection of the optimal cable cross section depending on the power of the electric motor.
No. 9. Removing the pump by the power cable
Another common cause of failure of submersible pumps. When pulling out the cable, a leak occurs in the place where the cable is connected to the pump casing. This leads to the fact that the inside of the electric motor gets water and disables the unit. The same damage occurs when the Gnome is transported by the cable or when objects are dropped on the power cord to it.
№ 10. Wrong direction of rotation of the impeller
When starting the pump, make sure that the shaft rotates in the right direction. Determining the correctness of rotation is very simple: when turned on, the pump will rotate in the opposite direction, indicated by the arrows on the unit housing (or in the figure in the passport).
If the pump rotates in the direction of the arrow, the connection is incorrect and the impeller will soon fail. To solve the problem, open the automatic switch and switch two of the three wires of the cable, and then check the direction of rotation again.
Diagnostics of malfunctions and their elimination
Before proceeding with the analysis of the pump and its repair, it is necessary to correctly determine what caused the failure. Consider the most common symptoms that occur when a failure of the pump "Gnome":
Electric pump does not start
Possible causes and methods to eliminate them:
- The impeller is jammed.
- Faulty capacitor in the power supply circuit.
- Open circuit, burning contacts.
- Burned stator winding.
- The failure of the motor.
- Engine bearing seizure.
- Lack of tension in a network or break in power supply.
Having verified that there are no problems with power supply, it is necessary to disconnect the “Gnome” pump from the power supply network and disassemble it in order to identify the reason why it does not start. Inspect the bearings, impeller, assess the condition of the motor windings.
The engine is running, but the pump does not pump water.
The pump engine “Gnome” works, but at the same time it does not pump water.The sound of a running engine may be weaker, uneven. Possible reasons:
- Clogged mesh filter or outlet.
- Engine running with insufficient power.
- Bearing wear and motor speed reduction.
- There is no pumped liquid, or it has become too viscous and dense.
- Damage to the water supply line (pipes, hoses).
In this case, you need to make sure that there is no damage to the pipes and hoses, there is water in the water source. If everything is in order, then it is necessary to disconnect the equipment from the mains and inspect the inlet filter and the outlet. If necessary, clean them and try to start the pump. If the bearings are worn, they will need to be replaced (see below).
Pump starts and shuts off immediately
When you start the pump "Gnome" a few seconds and then spontaneously turns off. This may be a symptom of the following malfunctions:
- The failure of the float switch.
- Short circuit in the motor circuit.
- The pump has overheated and the thermal fuse has tripped.
- Extremely low voltage in the mains.
- Impeller lock.
- The fluid in which the pump is immersed does not correspond to its operating ranges (too hot, viscous, with high density, etc.)
In this case, it is necessary to disconnect the “Dwarf” electric pump from the network and try again to turn it on after 30-90 minutes, after making sure that the required voltage is present in the power supply network. This time is enough to cool the overheated pump. If the pump stop is repeated, then it must be removed and disassembled to identify and correct the problem.
The pump works, but the pressure is small
Pump "Dwarf" pumps water, but the water pressure is much lower than it was before. Possible reasons:
- Leak on the water supply line (hoses, pipes).
- Low mains voltage.
- Contamination of the impeller and insufficient speed of its rotation.
- Wrong direction of rotation of the impeller.
- Large gap between the wheel and the movable disc.
- Worn impeller.
If the low head is not the result of a low line voltage or a line leak,The pump should be disconnected from the power supply, removed from the pumped liquid and disassembled for inspection and repair work.
At wear of the driving wheel its replacement is made. When clogged or improperly installed after self-assembly, the unit should be disassembled, cleaned and set the wheel in the correct position.
Assembly Disassembly Rules
The design of the pump “Gnome” is very simple, and the housing is quick-disconnecting, which allows disassembling it without any problems. This does not require special tools. Begin to disassemble with detaching the three nuts of the receiving mesh filter and removing the grid itself. Then nuts of fastening of a cover turn away, and it acts in film together with an installation and mobile disk. Unscrew the impeller nut, after which the wheel is freely removed.
All parts should be removed carefully without undue force. Symmetric parts must be numbered and marked (left / right, top / bottom) in order to avoid incorrect installation during assembly. It is recommended to replace the rubber parts in the assembly process with new ones using repair kits designed for this model.
During long-term operation of the “Dwarf” pump, problems may arise with loosening the nuts on the housing, sincethey are rusted or covered with a layer of lime sediment. In this case, the nuts can be cut "grinder", and the assembly to use new, suitable in shape and size.
Repair parts pump "Gnome"
Having considered the causes of malfunctions of pumps “Gnome”, you can see that almost all problems are solved when replacing the following parts: bearings, impeller, impeller shaft. Also, some faults are eliminated after adjusting the gap between the impeller and diaphragm.
Bearing Replacement Sequence
When the bearings are abraded, the pump can pump water, but at the same time produce unusual sounds caused by friction and rocking of worn bearings. Bearings must be replaced if there are gaps greater than 0.1-0.3 mm. This usually occurs after 3-6 years of operation of the electric pump "Gnome".
The process of replacing bearings is very simple: the pump is disassembled, the bearings are removed and replaced with new ones, taken from a special repair kit.You should not use self-made similarity of bearings or from analogs from repair kits of other modifications, since this may damage the equipment again as soon as possible.
Replacing the impeller
To replace the impeller, it is necessary to disassemble the “Gnome” electric pump and remove the impeller. Then install a new impeller and assemble the pump in reverse order. When mounting the cover with the installation-movable disk, it is necessary to screw the fasteners onto the studs and twist them simultaneously until the minimum clearance between the impeller blades and the disk cover is reached.
After assembly, it is required to check for tightness and, if it is broken, then abandon the use of a permanently damaged electric pump.
In some cases, with the availability of experience and appropriate equipment, it is possible not to replace the impeller with a new one, but to try to correct the existing annular workings with the help of surfacing with its subsequent processing on a lathe.
Repair of the impeller shaft and housing
In the presence of damage to the working shaft (bend, crack) it is best to make a complete replacement. The body of the “Dwarfs” is theoretically repairable, but in practice it is practically impossible to implement it correctly. In nine out of ten cases, the hermeticity of the case will be broken, and this deficiency can be corrected only at the factory or at a service center.
Given that such failures are found at pumps that have spent a considerable period of time, and therefore are not subject to warranty service, it is necessary to think about the expediency of repair. In most cases, it is faster, cheaper and easier to purchase a new submersible pump.
Adjustment of the gap between the impeller and diaphragm
The main reason for reducing the head and performance of the “Gnome” electric pump is the increase in the gap between the impeller and the diaphragm during operation. To reduce the gap, it is necessary to adjust it. To do this, remove the bottom of the filter and unscrew the top nut. Then tighten the nuts from different sides of the diaphragm until it comes into contact with the impeller.
Then unscrew the lower nuts half a turn.With this adjustment, the gap will be 0.3-0.5 mm. The adjusted location of the diaphragm relative to the impeller is fixed with upper nuts. After the adjustment is completed, it is necessary to check the ease of rotation of the impeller, it should rotate without application of force.
Repair of the pump motor "Gnome"
Gnome pumps are equipped with a reliable asynchronous electric motor. Independently repair an electric motor is very difficult. The maximum that can be done without having special stands is to determine the resistance of the motor windings using a household multimeter. If the resistance indicator tends to infinity, then it means that the winding is damaged and its replacement is necessary. To replace the winding will require complex disassembly of the electric motor and the presence of a rewinding machine.
But the main difficulty lies in the assembly process - the unit must be assembled in such a way as to provide a perfect barrier against the ingress of water into the electric motor.That is why the repair of the engine of the pump "Gnome" is better to entrust the professionals.
Repair and overhaul
In order to avoid malfunctions, it is necessary to perform timely maintenance of the “Gnome” electric pump recommended by the manufacturer. MOT includes:
- oil change every 200-250 hours of operation;
- checking the level and quality of oil - 2 times a month;
- flushing the pump with clean water after pumping water with a high content of solid particles;
- adjustment of the gap between the impeller and the diaphragm;
- inspection of the housing, bearings, impeller and shaft.
The current repair of the “Dwarf” pumps is carried out when signs of a malfunction appear or when the pump is not running. Capital repairs need to be made after 25 thousand business hours. Overhaul begins with disassembling the unit and determining the feasibility of repair work.
Conclusions and useful video on the topic
Disassembly of the electric pump "Gnome":
Repair of the Ukrainian Pedrol pump, an analogue of the Gnome electric pump:
Gnome electric pumps are reliable units for pumping clean and dirty water that can serve its owner for more than 25 years. Proper operation and installation, as well as timely maintenance and elimination of causes leading to breakdowns, guarantee uninterrupted operation of the equipment. Most of the faults of the “Dwarf” pumps can be repaired on their own without the involvement of repair technicians.