How to achieve efficient space ventilation with recessed in-line duct exhaust fans?

Working principle and structural characteristics of embedded inline duct exhaust fan

In the ventilation system of modern building space, embedded inline duct exhaust fan has become an important equipment for achieving good indoor air quality with its unique design and high efficiency. To give full play to its effectiveness, we first need to have a deep understanding of its working principle and structural characteristics.

The working principle of the embedded inline duct exhaust fan is based on the combination of aerodynamics and mechanical movement. From an aerodynamic point of view, when the exhaust fan is running, the fan blades rotate at high speed, and the shape and angle of the blades exert force on the air, so that the air in the center area of the fan blades is quickly discharged, forming a local low-pressure area. According to the principle of gas pressure, the air in the surrounding environment will flow to this low-pressure area continuously due to the pressure difference, thereby realizing the air intake. The inhaled air flows along the direction of the pipe under the push of the fan blades, and is finally discharged to the outside, forming a complete air circulation cycle. In this process, the flow speed and direction of the air are affected by the shape and rotation speed of the fan blades and the structure of the pipe.

From the perspective of mechanical movement, embedded inline duct exhaust fans are usually composed of key components such as motors, blades, and bearings. As the core power source, the motor converts electrical energy into mechanical energy and drives the blades to rotate at high speed. Different types of motors, such as AC motors and DC motors, differ in performance and applicable scenarios. AC motors have simple structures and low costs, and are suitable for general homes and commercial places; DC motors have the advantages of good speed regulation performance, high efficiency, and energy saving, and are more suitable for places with high ventilation requirements and flexible adjustment. The design of the blades is also crucial. Its material, shape, and angle directly affect the air propulsion efficiency and noise level. Common blade materials include plastic and metal. Plastic blades are light and low in cost, but relatively weak in durability; metal blades have better strength and durability. The shape of the blades is mostly propeller-like. Through reasonable angle design, it can generate greater thrust when rotating and improve the air delivery efficiency. As a component that supports the rotation of the blades, the quality and lubrication of the bearings affect the running stability and service life of the motor. Good bearing design and lubrication can reduce friction, noise and energy consumption.

In terms of structural characteristics, the biggest feature of embedded inline duct exhaust fans is their embedded design. This design enables them to be cleverly hidden in spaces such as the ceiling, wall or duct mezzanine of a building, without occupying the effective use area of the room, keeping the space neat and beautiful. Compared with traditional surface-mounted exhaust fans, embedded design better meets the dual needs of modern architecture for spatial aesthetics and functionality. At the same time, the embedded structure requires the exhaust fan to be more compact in size and the layout between the components to be more precise. In order to adapt to different installation spaces and duct specifications, embedded inline duct exhaust fans are available in a variety of sizes and shapes. For example, for narrow duct spaces, flat-shaped exhaust fans can be selected; for larger ventilation needs, larger-sized and higher-power models can be used.

In addition, the shell design of the embedded inline duct exhaust fan is also of great significance. The shell not only protects the internal components, but also affects the performance and service life of the exhaust fan. High-quality shells are usually made of corrosion-resistant and high-temperature resistant materials, such as stainless steel, engineering plastics, etc., and can operate stably under various complex environmental conditions. The sealing design of the shell is also key. A good seal can prevent air leakage and ensure ventilation effect, while preventing dust, moisture, etc. from entering the exhaust fan and damaging the motor and other components. Some high-end embedded inline duct exhaust fans are also equipped with a protective net to prevent foreign matter from entering the pipeline, further ensuring the normal operation of the equipment.

In practical applications, the working principle and structural characteristics of embedded inline duct exhaust fans make them play an important role in many places. In home decoration, they are often used in kitchens, bathrooms and other spaces that are prone to produce oil smoke, moisture and odor. By embedding the exhaust fan in the ceiling or wall and connecting the pipe to the outside, the dirty air can be quickly and effectively discharged to keep the indoor air fresh. In commercial buildings, such as shopping malls, office buildings, hotels, etc., embedded inline duct exhaust fans are an important part of the ventilation system. They can be combined with central air-conditioning systems to achieve air circulation and purification of the entire building space, providing people with a comfortable and healthy indoor environment. In the industrial field, for some workshops or warehouses with high requirements for air quality, embedded inline duct exhaust fans can timely discharge harmful gases and dust to ensure the health of workers and production safety.

A deep understanding of the working principle and structural characteristics of the embedded in-line duct exhaust fan is the basis for the rational selection, correct installation and effective use of the device. Only by fully understanding its working principle and structural characteristics can we maximize its ventilation efficiency according to different usage scenarios and needs, and create a more comfortable and healthy indoor space environment for people.

Key performance parameters analysis: balance between air volume, static pressure and noise ratio

The performance of embedded inline duct exhaust fans is determined by multiple key parameters, among which air volume, static pressure and noise ratio are the core indicators to measure its ventilation effect and user experience. In practical applications, how to find the best balance between these three parameters becomes the key to achieving efficient space ventilation.

Air volume refers to the volume of air that an exhaust fan can deliver per unit time, usually in cubic meters per hour (m³/h). It directly reflects the ventilation capacity of the exhaust fan and is the primary parameter to measure whether it can meet the ventilation needs of the space. When choosing an embedded in-line duct exhaust fan, it is necessary to determine the appropriate air volume based on factors such as the size of the space, the use function, and the density of people. For example, for a bathroom with a small area and few people, an exhaust fan with an air volume of 100-200 m³/h can generally meet the basic ventilation needs; while for a kitchen with a large area, a large amount of oil smoke and moisture, or a commercial place with a large number of people and a large demand for air circulation, it is necessary to choose an exhaust fan with an air volume of 300-1000 m³/h or even higher.

However, the larger the air volume, the better. On the one hand, excessive air volume will lead to increased energy consumption and higher operating costs; on the other hand, in some cases where the pipeline system is complex and the resistance is large, simply pursuing a large air volume may not achieve the desired ventilation effect. This is because the actual output of the air volume will be affected by factors such as pipeline resistance and static pressure. If the pipeline is too long, there are too many bends, or the pipe diameter is too small, the resistance to air flow will increase, making the actual air volume of the exhaust fan lower than the nominal value. Therefore, when considering the air volume, it is necessary to comprehensively evaluate the situation of the entire ventilation system to ensure that the air volume of the selected exhaust fan can match the pipeline system to achieve efficient ventilation.

Static pressure refers to the ability of the exhaust fan to overcome the resistance of the duct and maintain air flow, usually measured in Pascals (Pa). In a ventilation system, when air flows in the duct, it will be affected by various resistances such as friction resistance, bend resistance, and air outlet resistance. These resistances will consume the energy of the exhaust fan and reduce the ventilation effect. Therefore, the exhaust fan needs to have sufficient static pressure to overcome these resistances and ensure that the air can be smoothly transported to the designated location. Generally speaking, the longer the duct, the smaller the diameter, and the more bends, the greater the static pressure required.

For some complex ventilation systems, such as centralized ventilation systems in multi-story buildings or long-distance pipeline transportation systems, it is crucial to choose embedded in-line duct exhaust fans with higher static pressure. However, too high static pressure can also bring some problems, such as increased equipment costs and increased operating noise. Therefore, when determining the static pressure parameters, it is necessary to accurately calculate and reasonably select according to the actual pipeline layout and ventilation requirements. Professional ventilation design software can be used to simulate air flow under different static pressures to find the optimal static pressure value that can meet ventilation requirements while controlling costs and noise.

Noise ratio is an important indicator to measure the comfort of using embedded in-line duct exhaust fans. In actual use, the noise generated when the exhaust fan is running will affect people's lives and work. Therefore, while pursuing efficient ventilation, the noise must be controlled within a reasonable range. The generation of noise is mainly related to factors such as the operation of the motor, the rotation of the fan blades, and the flow of air. The quality and balance of the motor, the shape and dynamic balance performance of the fan blades, and the resonance of the pipeline will affect the noise level of the exhaust fan.

In order to reduce noise, manufacturers usually adopt a variety of technical measures. For example, optimize the design and manufacturing process of the motor to improve the balance and stability of the motor; use silent bearings to reduce the noise caused by friction; dynamically balance the fan blades to avoid vibration noise caused by unbalanced fan blades; in the pipeline design, use sound-absorbing materials and shock-absorbing devices to reduce the noise generated by air flow and equipment vibration. When choosing an exhaust fan, you should pay attention to its noise index and try to choose a product with lower noise. At the same time, reasonable installation and layout can also effectively reduce noise, such as avoiding installing the exhaust fan near the bedroom or rest area to reduce the interference of noise to people.

The three key performance parameters of air volume, static pressure and noise ratio are interrelated and mutually constrained. In practical applications, it is necessary to comprehensively consider these three parameters according to specific usage scenarios and needs to find the best balance point. For example, in the ventilation of a home kitchen, the static pressure can be reasonably controlled on the premise of ensuring that the demand for oil fume exhaust is met (appropriately select a larger air volume) to avoid excessive static pressure due to unreasonable pipeline design, which increases noise and energy consumption; at the same time, choose exhaust fan products with lower noise to ensure that there is no excessive noise interference during the cooking process. In commercial office spaces, it is necessary to strictly control the noise level while meeting the ventilation needs of large areas to provide a quiet and comfortable working environment. Only by accurately grasping and reasonably deploying the air volume, static pressure and noise ratio can the performance advantages of the embedded in-line duct exhaust fan be fully utilized to achieve efficient and comfortable space ventilation effects.

Installation optimization plan: pipeline matching and airflow organization design

The installation effect of embedded inline duct exhaust fans directly affects their ventilation performance, and duct matching and airflow organization design are two key links in the installation process. Reasonable duct matching can ensure that the performance of the exhaust fan can be fully utilized, and scientific airflow organization design can achieve efficient air circulation in the space. The two complement each other and lay the foundation for achieving efficient space ventilation.

In terms of pipe matching, the material selection of the pipe should be considered. Common ventilation duct materials include galvanized steel, PVC plastic, stainless steel, etc. Galvanized steel has the characteristics of high strength and good corrosion resistance, and is suitable for ventilation systems in most ordinary environments, especially centralized ventilation ducts in commercial buildings and industrial sites; PVC plastic pipes have the advantages of light weight, low price, and easy installation, and are often used in kitchen and bathroom ventilation ducts in home decoration; stainless steel pipes have excellent corrosion resistance and high temperature resistance, and are suitable for some places with high hygiene requirements or harsh environments, such as food processing workshops and hospitals. When choosing the material of the pipe, it is necessary to comprehensively consider factors such as the use environment, ventilation requirements, and budget to ensure that the pipe material can meet the requirements of long-term stable operation.

The diameter and length of the duct have an important impact on the ventilation effect. The diameter should be matched according to the air volume and static pressure of the exhaust fan. Generally speaking, a small diameter will increase the resistance to air flow, resulting in air volume loss and increased energy consumption; a large diameter will cause material waste and space occupation. In actual design, the appropriate diameter can be calculated based on the nominal air volume of the exhaust fan and the relevant ventilation design specifications. For example, for an exhaust fan with an air volume of 300 m³/h, the diameter can be selected to be about 100mm when the horizontal duct length does not exceed 5 meters. The length of the duct also needs to be reasonably controlled. Too long ducts will increase air flow resistance and reduce ventilation efficiency. Therefore, when laying out the duct, the length of the duct should be shortened as much as possible, and unnecessary bends and branches should be reduced to reduce resistance and improve ventilation effect. If long ducts or multiple bends cannot be avoided due to reasons such as building structure, it is necessary to select an exhaust fan with a higher static pressure and take corresponding optimization measures in the duct design, such as increasing the duct diameter and using ducts with smooth inner walls to reduce resistance.

In addition to the pipe diameter and length, the connection method of the pipe cannot be ignored. Good pipe connection can ensure the sealing of the system, prevent air leakage, and improve ventilation efficiency. Common pipe connection methods include flange connection, socket connection and bonding. Flange connection is suitable for pipe systems with larger pipe diameters and higher pressures. It has the advantages of firm connection and good sealing, but the installation is relatively complicated and the cost is high; socket connection and bonding are suitable for connections with smaller pipe diameters such as PVC plastic pipes. The operation is simple and the cost is low, but attention should be paid to ensure the sealing of the connection parts to avoid air leakage. During the installation process, the pipe connection should be carried out in strict accordance with the specifications, and sealing materials such as sealants and sealing rings should be used to ensure the airtightness of the pipe system.

In terms of airflow organization design, the first thing to do is to determine the reasonable position and form of the air outlet. The air outlet is the channel for air to enter and exit the ventilation system. Its position and form directly affect the flow path and distribution of air in the space. In the indoor space, the position of the air supply and exhaust outlets should be reasonably arranged according to the function of the space, the area where people move around, and the law of air flow. For example, in the bedroom, the air supply outlet should be set as far away from the head of the bed as possible to avoid blowing directly at people, and the exhaust outlet can be set on the side close to the odor source such as the bathroom or kitchen to speed up the discharge of dirty air; in the large space of commercial places, the air supply and exhaust outlets can be symmetrically distributed or evenly distributed to ensure that the air can flow evenly to every corner.

There are also many options for the form of air vents, such as louver vents, diffuser vents, strip vents, etc. Different forms of air vents have different airflow diffusion characteristics and applicable scenarios. Louver vents have the function of adjusting wind direction and air volume, and are suitable for places where the direction of airflow needs to be flexibly controlled; diffuser vents can make the air diffuse evenly in all directions, and are suitable for places with high requirements for uniform airflow distribution, such as conference rooms, offices, etc.; strip vents have a long and narrow shape, and are suitable for places with long and narrow spaces or where directional air supply is required. When choosing the form of air vents, they should be reasonably matched according to the specific ventilation needs and space characteristics to achieve the best airflow organization effect.

In addition, the airflow organization design also needs to consider obstacles and airflow interference factors in the space. In actual space, there are often obstacles such as furniture, equipment, and partitions. These obstacles will affect the flow of air and form airflow dead corners. Therefore, when designing an airflow organization plan, it is necessary to fully consider these factors and reasonably adjust the position of the air outlet and the direction of the pipeline to avoid obstruction of air flow. For example, by adding auxiliary air outlets or adjusting the pipeline layout, the air can be guided to bypass obstacles and achieve effective air circulation. At the same time, care should be taken to avoid mutual interference between airflows of different ventilation systems. For example, the ventilation ducts in adjacent rooms should be kept at a certain distance to prevent air cross-flow and affect the ventilation effect.

The installation optimization of embedded in-line duct exhaust fans requires careful planning and implementation in terms of duct matching and airflow organization design. By rationally selecting duct material, duct diameter and connection method, scientifically designing the position and form of the air outlet, and fully considering various factors in the space, the efficient operation of the ventilation system can be ensured, good space ventilation effect can be achieved, and a comfortable and healthy indoor environment can be created for people.

Maintenance points and common fault diagnosis methods

Embedded in-line duct exhaust fans will inevitably face various losses and problems during long-term operation. Scientific and reasonable maintenance as well as timely and accurate fault diagnosis are the key to ensuring their continued efficient operation and achieving efficient ventilation of the space.

1. Maintenance points

(I) Daily cleaning and maintenance

• Blade cleaning : The blades of the embedded in-line duct exhaust fan are the most prone to dust accumulation. In daily use, dust, oil smoke and other impurities in the air will continue to adhere to the surface of the blades. When the blades accumulate too much dust, it will not only increase the weight of the blades, resulting in an increase in the motor load, but also affect the aerodynamic performance of the blades and reduce the exhaust efficiency. It is recommended to conduct an appearance inspection of the blades once a week. If obvious dust is found on the surface of the blades, they should be cleaned in time. When cleaning, disconnect the power supply first to ensure safe operation. For detachable blades, use a soft brush to gently brush off the surface dust, and then wipe with a damp cloth; for non-detachable blades, use a long-handled soft brush to clean deep inside the pipe, or use a vacuum cleaner to remove surface dust.
• Duct cleaning : The duct of the exhaust fan is a channel for air circulation. After long-term use, dust, oil and other dirt will accumulate on the inner wall of the duct. These dirt will hinder air flow, increase ventilation resistance and reduce ventilation efficiency. The outside of the duct should be checked once a month to see if there is any damage or air leakage. The inside of the duct needs to be cleaned every 3-6 months. When cleaning the inside of the duct, you can choose the appropriate method according to the material and structure of the duct. For shorter and easily disassembled ducts, you can disassemble them, soak them in a special duct cleaner, and then rinse them with clean water; for longer fixed ducts, you can use professional duct cleaning equipment, such as a duct cleaning robot, to clean the inside of the duct with the brushes and vacuum devices it carries.
• Casing cleaning : The casing of the exhaust fan not only protects the internal components, but its appearance also affects the overall appearance. For daily cleaning, you can wipe the surface of the casing with a clean damp cloth to remove dust and stains on the surface. If there are stubborn stains on the casing, you can use a small amount of neutral detergent to clean it, but be careful to avoid the detergent from penetrating into the exhaust fan and damaging the electrical components.

(II) Regular maintenance

• Motor maintenance : The motor is the core component of the embedded in-line duct exhaust fan, and its performance directly affects the operating efficiency and service life of the exhaust fan. The motor should be maintained every six months. First, check whether the motor terminals are firm and whether there is any looseness or oxidation. If the terminals are found to be loose, they should be tightened in time; if oxidation occurs, they should be polished clean with sandpaper before reconnecting. Secondly, check the lubrication of the motor bearings. If the bearings are not lubricated enough, add an appropriate amount of high-temperature resistant grease. When adding grease, be careful not to add too much to prevent the grease from being thrown out and contaminating the fan blades and pipes. In addition, the operating temperature of the motor needs to be checked. Under normal circumstances, the temperature of the motor should not be too high during operation. If the motor temperature is found to be abnormally high, the machine should be stopped immediately for inspection to eliminate the fault.
• Belt (if any) maintenance : Some embedded in-line duct exhaust fans use belt drive, and the belt will wear, age and other problems during long-term operation. The belt should be checked for wear every six months to see if there are cracks or wear marks on the belt surface, and whether the belt is appropriately tight. If the belt is severely worn or cracked, it should be replaced with a new one in time; if the belt is too loose or too tight, the tightness of the belt can be adjusted by adjusting the position of the motor. When adjusting, the belt should be of moderate tightness. Too looseness will cause the belt to slip and reduce transmission efficiency; too tightness will increase the load on the motor and bearings and accelerate component wear.
• Electrical system inspection : The electrical system of the exhaust fan includes power cords, switches, capacitors and other components. The normal operation of these components is the basis for the exhaust fan to work. A professional electrician should be invited to conduct a comprehensive inspection of the electrical system every year. Check whether the power cord is damaged or aged. If the outer skin of the power cord is found to be damaged, it should be replaced with a new power cord in time; check whether the switch is flexible and reliable, and whether the contacts are in good contact. If the switch fails, it should be repaired or replaced in time; check whether the capacitor has bulging, leakage, etc. If the capacitor is damaged, it needs to be replaced with a capacitor of the same specification. In addition, it is necessary to check the grounding of the electrical system to ensure that the exhaust fan is well grounded to ensure safe use.

(III) Maintenance under special circumstances

• Humid environment : When using embedded inline duct exhaust fans in humid environments, such as bathrooms and kitchens, the electrical components of the exhaust fan are easily damaged by moisture. Therefore, when using in a humid environment, in addition to daily cleaning and regular maintenance, it is also necessary to strengthen the protection of electrical components. A waterproof cover can be installed on the outside of the exhaust fan to prevent water vapor from directly entering the exhaust fan. At the same time, the insulation performance of electrical components should be checked regularly. If the insulation resistance is found to be reduced, it should be dried or the damaged parts should be replaced in time. In addition, after using in a humid environment, the operating time of the exhaust fan should be appropriately extended to discharge the moisture in the pipe and reduce the accumulation of moisture in the pipe.
• High temperature environment : For embedded inline duct exhaust fans used in high temperature environments, such as industrial workshops, the heat dissipation of motors and other components is particularly important. In order to ensure the normal operation of the exhaust fan in a high temperature environment, the heat dissipation measures for the motor should be strengthened. Heat sinks can be installed on the motor casing to increase the heat dissipation area; auxiliary cooling fans can also be installed around the exhaust fan to accelerate air circulation and help the motor dissipate heat. In addition, the operating temperature and insulation performance of the motor must be checked regularly. If the motor temperature is too high, measures should be taken to reduce the ambient temperature or suspend the use of the exhaust fan, and restart it after the motor temperature returns to normal. At the same time, pay attention to the selection of high temperature resistant lubricants and electrical components to meet the use requirements of high temperature environments.
• Dusty environment : In dusty environments, such as factory workshops, construction sites, etc., exhaust fans are more likely to accumulate dust, and the maintenance frequency needs to be increased accordingly. It is recommended to clean the fan blades and pipes once a week, and conduct a comprehensive inspection and cleaning of the motor and other components once a month. In a dusty environment, a high-efficiency air filter can be installed at the air inlet of the exhaust fan to filter out dust in the air and reduce the amount of dust entering the exhaust fan. At the same time, the air filter should be replaced regularly to ensure its filtering effect. In addition, for exhaust fans in dusty environments, special attention should be paid to checking the tightness of the pipes to prevent dust from entering the room from the pipe connections and affecting the indoor air quality.

2. Common fault diagnosis methods

(I) Exhaust fan does not work

• Power supply problem : First check whether the power socket has electricity. You can use a tester or a multimeter to test it. If the socket has no electricity, check whether the circuit breaker of the circuit where the socket is located has tripped. If it has tripped, check whether there are short circuits, overloads, etc. in the circuit, and reclose the circuit after troubleshooting. If the socket has electricity, check whether the power cord of the exhaust fan is damaged or broken, and whether the plug and the socket are in good contact. If the power cord is damaged, replace it with a new one; if the plug and the socket are in poor contact, adjust the plug or replace the socket.
• Switch failure : Check whether the exhaust fan control switch is damaged. You can determine this by measuring the voltage across the switch. If there is no voltage across the switch when it is turned on, it means that the internal contacts of the switch are poorly connected or damaged, and a new switch should be replaced.
• Motor failure : If the power supply and switch are normal, but the exhaust fan still does not work, it may be a motor failure. Check whether the motor winding is open or short-circuited. You can use a multimeter to measure the resistance value of the motor winding. If the resistance value is infinite, it means that the winding is open; if the resistance value is zero or far below the normal value, it means that the winding is short-circuited. For motors with open or short-circuited windings, new motors are generally required. In addition, the motor bearing is stuck, which will cause the motor to stop running. At this time, you can manually turn the fan blades. If it feels difficult or impossible to turn, it means that the bearing is stuck and the bearing or motor needs to be replaced.
• Capacitor failure : For exhaust fans that use capacitors to start, capacitor damage can also cause the motor to fail to start. Check whether the capacitor has bulging, leakage, etc. If the capacitor looks normal, use the capacitor range of the multimeter to measure the capacitor capacity. If the capacitor capacity is significantly lower than the nominal value or zero, it means that the capacitor is damaged and should be replaced with a capacitor of the same specification.

(II) Insufficient exhaust volume

• Fan blade problem : Check whether the fan blades are too dusty or deformed. If the fan blades are too dusty, it will affect the aerodynamic performance of the fan blades and reduce the exhaust efficiency. Clean the fan blades according to the above cleaning method. If the fan blades are deformed, it will cause the fan blades to be unbalanced when rotating, affecting the exhaust volume. For slightly deformed fan blades, you can try to correct them; for severely deformed fan blades, you need to replace them with new ones.
• Pipeline problems : Check whether the pipeline is blocked, damaged or leaking. If the pipeline is blocked, use pipeline dredging tools to dredge it, such as pipeline dredging tools, high-pressure water guns, etc. If the pipeline is damaged or leaking, the damaged pipeline section should be repaired or replaced in time. At the same time, check whether the length and curvature of the pipeline meet the design requirements. Pipes that are too long or have too many bends will increase ventilation resistance and reduce exhaust volume. If the pipeline design is unreasonable, consider optimizing the pipeline layout to reduce unnecessary bends and length.
• Motor performance degradation : After long-term use, the performance of the motor will gradually decline, resulting in reduced speed and insufficient exhaust volume. Check whether the motor speed is normal. You can use a tachometer to measure it. If the motor speed is significantly lower than the rated speed, it may be caused by aging of the motor windings, bearing wear, etc. In the case of aging of the motor windings, it is generally necessary to replace the motor; in the case of bearing wear, the bearings can be replaced and an appropriate amount of grease can be added.
• Installation issues : Check whether the exhaust fan is installed correctly, such as whether the connection between the exhaust fan and the pipe is tight, whether there is air leakage; whether the installation position of the exhaust fan is reasonable, and whether it affects the air circulation. If the installation is improper, the exhaust fan should be reinstalled to ensure that it is firmly installed, the connection is tight, and the installation position is conducive to the air in and out.

(III) Excessive noise

• Unbalanced fan blades : During long-term use, the fan blades may become unbalanced due to uneven dust accumulation, collision deformation, etc., which may cause vibration and noise when rotating. Check whether the fan blades have dust accumulation and deformation, and clean and correct them according to the above methods. If the fan blade imbalance problem is more serious, you can use a professional dynamic balancer to test and adjust the fan blades to ensure the balance accuracy of the fan blades.
• Bearing wear : Bearing wear is one of the common reasons for the excessive noise of exhaust fans. When the bearing is worn, the motor will produce greater friction and vibration during operation, thus making noise. Check whether the bearing is worn, lacking oil, etc. If the bearing is severely worn, it is necessary to replace it with a new one; if the bearing is lacking oil, an appropriate amount of high-temperature resistant grease should be added. When adding grease, pay attention to cleaning the bearing and the oil filling port to prevent impurities from entering the bearing.
• Pipeline vibration : If the pipeline is not firmly fixed or there is resonance between the pipeline and the exhaust fan, wall and other components, it will also cause excessive noise. Check the fixing of the pipeline and ensure that the fixing parts such as the pipeline bracket and hanger are firmly installed without looseness. If there is resonance between the pipeline and other components, shock-absorbing pads or shock-absorbing brackets can be installed between the pipeline and the components to reduce vibration transmission. In addition, it is necessary to check whether there is any foreign matter inside the pipeline. If there is any foreign matter, it should be removed in time.
• Motor failure : Faults such as short circuit, open circuit, and rotor eccentricity in the motor winding can also cause abnormal noise when the motor is running. Determine whether the motor is faulty by measuring the resistance value of the motor winding and checking the operating temperature of the motor. If the motor fails, it should be repaired or replaced according to the specific situation.

The maintenance and fault diagnosis of embedded in-line duct exhaust fans is a meticulous and professional job. Only by mastering the correct maintenance points and fault diagnosis methods and strictly following the requirements can we ensure that the exhaust fans always operate efficiently and provide good ventilation for the space.