What Makes A Great Ceiling Fan
What looks good in your space is a combination of the space itself and your personal taste. As such it is worth keeping in mind that great architecture should be supported by equally good fixtures, and as fans are one of the more obvious features of a room it is worth investing in something that complements your design.
The most common complaint about ceiling fans is noise. There are many causes of this, but they can roughly be broken into the following categories:
- Mechanical noise: The key sources are poor quality bearings or misshapen parts. There is no excuse for mechanical noise from a quality fan, although motor quality related noise is a common concern on budget fans.
- Turbulence: As fan blades move through the air they can create turbulence in addition to desirable laminar airflow. Turbulence is essentially spiralling eddies of air off a blade’s trailing edge and tip. Turbulence is a significant cause of noise which can be minimised by selecting blades that: i) are thicker top to bottom, ii) don’t have features including holes and texture, and iii) are aerodynamically shaped.
- Vibration: All electric motors create some vibration, however sometimes vibration can lead to resonance through the fan housing or blades producing an audible hum. Vibration is largely mitigated by the use of quality materials and high precision manufacturing processes.
WOBBLE FREE ROTATION
Wobble is generally cited as the second most frustrating feature of poor quality ceiling fans. The main causes of fan wobble are: i) an unbalanced fan rotor, ii) unbalanced blade set, and iii) warped or twisted blades. To reduce or eliminate fan wobble good quality fans will:
- Have a factory balanced rotor, a process similar to balancing a car wheel
- Include a balanced blade set
- Have blades constructed from high quality materials resistant to warping
- Be supplied with a simple to use balancing kit
A good motor is always powerful enough to generate the required airflow and is well built, ensuring quiet longevity, but it is not necessarily big. In the US there has been a race to the biggest motor, which is perhaps good marketing but is bad engineering; so be mindful of motor marketing spin when reading US sourced ceiling fan information.
DC motors may be the way of the future being smaller and more efficient that AC motors, however issues with controlling them and noise have restricted their popularity and will likely result in them remaining a relatively fringe product until the technology matures.
SUPERIOR MATERIAL SELECTION
There is no right answer to what a fan should be built from, but be mindful of where a fan is to be used to ensure its aesthetic and functional longevity.
- Finish: The quality of the finish is crucial to keeping your fan looking good. Compromises in surface preparation or the paint used, or the type and thickness of the epoxy coating on raw metal finishes (e.g. brushed aluminium) can result in premature failure of the finish.
- Housing: Die cast aluminium and stainless steel are generally superior materials for the housing of a ceiling fan, and yet in benign environments lacquered mild steel and various types of plastics can also be used to good effect if well designed and manufactured.
- Blades: The best material type for blades is injection moulded resin because it resists warping and tends to maintain its finish the longest. Plus moulded blades allow for the use of aerodynamic blade designs to reduce turbulence. The next best option (and more affordable) is plywood with a laminated finish to match the housing finish. MDF (medium density fibreboard) and other cheaper woods are not stable enough and should be avoided. Any warping of the blades will result in fan wobble.
GOOD LIGHTING OPTIONS
Lighting should be an integral part of a ceiling fan’s design in terms of look and functionality. Some things to consider include:
- Diffuser quality: Good diffusers are constructed from two layers of glass with the inner coloured layer (often white) providing an even optical transparency and the outer structural layer being acid etched to further enhance the look and optical diffusion properties. Watch out for plastic diffusers or a single glass layer with the inner optical layer painted on to the structural outer layer.
- Hot spotting: Look for an even light distribution. You do not want to see spots that are significantly lighter or darker on the glass.
- Lamps / bulbs:
- Halogens: Consume more energy than CFLs or LEDs but produce the best quality light (colour render), are easily dimmable, affordable, produce good ambient light and don’t mind being turned on and off.
- CFLs: Are a greener solution than halogen lamps because they consume less energy, but are big, have inferior colour render characteristics to halogens, and need to warm up to reach full brightness.
- LEDs: Are likely to be the way of the future however the technology is not yet mature. Enormous R&D investments are being made to address issues with LEDs including: i) poor colour render, ii) highly directional light making them inferior for ambient lighting applications, and iii) high cost. Plus LEDs don’t like being mounted on the back of a ceiling fan because the heat generated by the motor of the fan reduces the life of the LEDs.
A THOUGHT ON THE NUMBER OF BLADES
A sailing yacht designer recently pointed out that there are differences in the performance characteristics of 3, 4 or 5 blade configurations, all of which are too subtle to worry about when it comes to ceiling fan fluid dynamics. As such the primary concerns are aesthetic, including:
- Fewer thinner blades are less intrusive reducing the false ceiling effect you can get with a larger number of wide blades
- An uneven number of blades can reduce the impact of strobing, which occurs when the blades of a fan pass beneath or close to a light source
FOR MORE INFORMATION REFER TO:
- Ceiling fan selection tips
- A guide to ceiling fans with lights
- The budget fan compromise, is it worth it?
- CSIRO’s opinion
- Noise: Air turbulence