Why is my ceiling fan making noise?

Why is my ceiling fan making noise?

From Superfan, India’s first super energy efficient ceiling fan

Ceiling fans are the primary thermal comfort appliance in India due to their simplicity, familiarity, cost-effectiveness, and efficiency (BLDC ceiling fans). Beyond these advantages, there are some drawbacks like lack of standardization, decrease in effectiveness in extremely humid conditions, and the noise from its operation. 

The standardization of fans is underway now through the efforts of government agencies like BIS and BEE. Ceiling fans cannot offer comfort in humid conditions as the thermal comfort from fans depends on the surrounding humidity. Know more about how ceiling fans work. Engineers can address the noise from ceiling fan fans, and popular brands have addressed the issue in few ways with some compromise on performance. 

Superfan has solved the same with their new Super Q fan in a unique way that is sustainable in terms of cost and performance. 

What causes ceiling fan noise? 

1. Mechanical noise 

A ceiling fan is an electromechanical machine with continuous moving parts. The friction between these parts can cause noise. Typically, it could be from a lack of lubrication from bearings, loose screws in blade mounting, or errant resonant vibrations from blades with the surroundings. 

2. Electronics noise 

Super energy-efficient ceiling fans like BLDC fans have electronics that control the motor. These electronics have some high-frequency components that can produce low humming noise at low speeds. These noises may be present in some BLDC ceiling fans, but they are overshadowed by other noises due to their low decibel level. 

3. Air-cutting noise 

This noise is a direct consequence of the way ceiling fan works – blades pushing the air to create a flow. The noise is proportional to the frequency at which the blade cuts(moves) the air, i.e as the speed of the fan increases the noise increases, 

N2 = N1+55 log (RPM2 / RPM1

Where N is noise level and RPM is the speed of the fan, the subscripts denote the state of the fan. 

The airflow from a fan has two components, laminar (smooth) flow and turbulent flow. The edges of the blade are the source of this turbulent flow, which is the source of this noise. At the highest speed step, the noise level of a typical fan can exceed 60 dBA. 

So, there are two causes to this noise – the rate of the blades cutting the air and the turbulence in the flow. 

How to make quiet ceiling fans? 

Engineers primarily work on the air-cutting noise to reduce the noise from a ceiling fan. As previously stated, the source of noise comes from the edges of the blades and the fan’s speed. Usually, fans require the rotational speed to be over 350 RPM to provide the required comfort. 

A typical aluminum ceiling fan blade is considered to have a thin foil shape i.e., a uniform thickness cross-section. The popular solution for quietness has been to make the blades with the airfoil. Airfoil is the 3D cross-section of a blade, there are numerous meaningful airfoil shapes and are chosen depending on the application. An efficient airfoil reduces turbulent flow and also generates more airflow at lower RPM to deliver the required comfort. As the airfoil minimizes both causes of air-cutting noise, it has been the obvious solution for fan designers. In recent years, such as Orient Aero Quiet, Crompton Silent Pro, and others have used this technology to launch their silent ceiling fans in India. 

These quieter ceiling fans are expensive because most of these fans are made of plastics. Many of these silent ceiling fans in the Indian market are copied designs of foreign designs, that had a different application. Hence these designs never accounted for cost-effectiveness in the design nor the performance. 

As the blades with airfoil have varied thickness cross-sections, aluminum can no longer be used. The use of plastics has some drawbacks – reduced productivity, expensive, lower efficiency. Plastic blades are produced by injection molding the productivity depends on the number of molds and post-processing and is significantly lower than aluminum blades. Plastics are usually more expensive and popular Indian silent fans use more plastics than necessary in their fans due to derived foreign solution. Plastic blades tend to have varied stiffness through the blade as the amount of material varies, this varied stiffness restricts the flexibility of the blade during its operation. An aluminum blade flexes depending on the thrust generated by the blades, this flex seems to minimize energy loss. 

How is the Superfan’s Super Q silent ceiling fan different? 

Superfan developed a new blade shape without the airfoil. Hence it can be manufactured with aluminum material. This shape achieves similar quietness and airflow of a blade with airfoil, while being more efficient. This unique shape delivers the required airflow (230 CMM) at about 240 RPM (48” fan). The noise level at this airflow is about 49 dBA at a level 7 feet from the center of the fan.  

As this is made of aluminum, the efficiency is higher, these fans generate 230 CMM airflow for 25 W electricity. More importantly, this silent solution can be scaled up unlike plastic blade as the productivity remain almost the same as a regular blade. 

There are more reasons than quietness to choose Super Q. Explore! 

Noise from ceiling fans affects people variedly – it affects conversations in the living room, impacts the classroom by clouding the teacher’s voice, reduces the auditory experience in theatres and auditoriums. Know more. 

Contact us at 1800 425 78737 or email at helpdesk@superfan.in to learn more. 

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