High flow ceiling fans & High speed ceiling fans

High flow ceiling fans & High speed ceiling fans

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

How ceiling fans move air?

A ceiling fan is a simple electrical appliance with blades mounted on a motor which rotates the blades to push the air and create airflow. The airflow from ceiling fans is measured in Cubic Meter Per Minute (CMM). The airflow has two components, the volume of air moved and the speed at which that volume of air moves. Fan designers vary the two components to make fans suitable for different applications with the same airflow.

What kind of airflow is produced in typical ceiling fans?

The airflow of a typical 48” ceiling fan in India is rated to be 230CMM, which is far greater than the fans used across the world. Most of the ceiling fans available in the market move a smaller volume of air at higher speeds to achieve the desired 230 CMM flow. These fans are commonly called high speed fans in the market with rotation speed greater than 350 RPM.

What happens when you increase the rotation speed of the ceiling fan?

The airflow of the ceiling fan varies with rotation speed (RPM) controlled by the speed of the fan rotation represented as Revolutions Per Minute (RPM).

According to fan laws , when RPM is increased by 10%, the airflow increases by 10%, and the total static pressure increases by 21%. (unless there is sufficient cross ventilation).

Are there risks of high speed air from ceiling fans?

Exposure to a ceiling fan delivering high speed air and pressure could cause health discomforts like congestion [1], dry eyes [3], nasal dryness [2], muscle stiffness & tiredness [4], etc. when you sleep or sit under it for a longer duration.

It is well known that airflow on a surface increases the evaporation rate, this is experienced every day while we blow on a cup of tea to cool it down. Similarly, a steady stream of high speed air on the exposed parts of the body like the face could increase the rate of removal of moisture leaving your eyes and nasal tracts dry [5]. People with sinus problems may be more prone to the effects of high speed air as their body tends to produce mucus to compensate for nasal tract dryness resulting in nose blockages and headaches [6]. Sleeping directly under high speed air without ventilation throughout the night could cause your muscles to tense up and cramp, leading to muscle stiffness and tiredness in the morning due to the excess pressure. [4]

To know more about the health discomforts caused by high speed ceiling fans, look at the links below :

Are there any fans without these heath discomforts ?

Yes! Superfan has designed a new blade shape that moved large volumes of air at an optimal speed to produce the required 230 CMM. The shift in approach to create airflow eliminates these health discomforts without compromising thermal comfort. Superfan calls this new type of fan as a high flow fans as they move more volume of air at an optimal speed to deliver the same comfort as a high speed fan.

Apart from health benefits, high flow fan offers quieter operation and higher efficiency. The quietness comes from the lower fan speed and the increase in efficiency is the result of eliminating turbulent flow by the blade shape.

Have these high flow fans been validated?

Superfan has combined its Q flow technology blade and its patented BLDC motor design to make a series of high flow fans called Super Q. The performance of Super Q has been measured at NABL certified laboratory and validated by the Bureau of Energy Efficiency (Ministry of Power, Government of India). The lab reports can be found here.

Apart from this Super Q fan has been recognized as the ‘Appliance of the year’ through NECA by the Ministry of Power, India.

Where these high flow fans are useful?

These high flow fans are suitable for the spaces where occupants intend to use these fans for longer durations. Suitable for bedrooms, living rooms, office spaces, all types of air-conditioned rooms etc.,

Are high speed fans always bad?

No, they are suitable for certain applications. They are more convenient for users to cool down in a short duration in open spaces with hot conditions. For example, spaces near hot machinery at factories, kitchen with hot stoves, waiting areas, dining spaces. etc.

There is no harm in using high speed ceiling fans for a shorter duration. But if you intend to stay under a fan for a longer duration, it is better to use a fan that delivers high flow at an optimal speed which provides overall comfort. This type of fan protects you from health discomforts, What happens when you increase the increases efficiency, and minimizes noise.

Comparison between high speed and high flow ceiling fans

Note: The efficacy will be on par with high speed fan at the high airflow mode in Super Q.
Note: The above results data were derived from 48-inch span size fan types.

The table 2 shows the technical contrast between high speed and high flow in terms of speed and airflow. As discussed above, each of the two types have specific use, an appropriate choice would give the best value to the consumer in terms thermal comfort, energy saving and health. Use Table 1 to choose the correct fan for your room and use.

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