AC vs DC fans? Any advantages of a DC fan?

[Cecil Lee]

Case Study 1: AC vs DC fans? Any advantages of a DC fan?

These are some considerations:

1. AC fans have been around ever since electricity has been invented.

2. Generally, some find that DC fans costs more. Thus, in the long term; running costs are cheaper with a DC fan. Thus you do the maths.

3. AC fans can only spin one direction. Thus, the fan blades are optimized to "blow" wind downwards.

3.1. Here, DC fans have a distinct advantage. DC fans can be made to spin clockwise or anti-clockwise. Thus if so, instead of "blowing" wind downwards, it can also be made to "suck" air up to the ceiling. Thus especially if one has a high ceiling; the air can be sucked upwards without still feeling the wind blowing dowards.

4. Any difference with how many blades a fan should have?

4.1. Many ceiling fans have at least 3 blades. Did you notice that many standing fans have more than three blades?

4.2. This has more to do with common sense than Feng Shui. For example, stealth helicopters have many blades some even as many as 6 or more. The more blades, the "smoother" the air flow and noise level.

4.3. This is why, a fan with one blade or two blades often wobbles and makes lots of noise.

4.4. It is similar to a car. A car with 3 cylinders / pistons can make lots of noise. Or how often when a motorcycle pass a person and we can hear the loud sound.

4.5. Contrast this with a car that has 6 cylinders or even 8 cylinders. A modern V6 car will often be ultra quiet compared to a standard 4 cylinder car.

 

 

[Cecil Lee]

Case Study 2: In theory, if a ceiling fan can suck up air instead of blowing it downwards, MAY cool more surface area.

1. For example, if the room has all glass windows.

2. When the fan blade is "reversed" to pull air-upwards.

3. The pulled air will flow from the ceiling downwards as shown in the illustration below:-

4. Although room with afternoon sun and glass windows become a green house effect.

5. Fortunately, glass dissipates heat much faster than a wall soaked with heat.

6. Please take note that all AC fans cannot reverse the fan blade flow from say clock-wise to anti-clock-wise. 

7. However, not all DC fans have such a feature.

7.1. If you intend to buy a DC fan, please take note of the above.

8. Imagine also, if one is in the living room. By blowing air upwards, it may or may not work for you.

9. Anyway, if you can still use the normal method of fan circulation if this does not appeal to you...

[Cecil Lee]

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