Maximum Ceiling Fan RPMs
Published by: Greg Tillotson
Webmaster for Hansen Wholesale
Ever wonder why ceiling fans only go so fast? Ever think that if manufacturers just made ceiling fans spin faster, they would move more air? Well, maybe you don't think of these kinds of things, but as the webmaster for the Largest Ceiling Fan Website online, I can't help but have such thoughts.
The fact is: There are UL standards that place limitations on ceiling fan manufacturers that prevent them making fans that spin too fast. These limitations for safety purposes and are meant to minimize the risk of injury should a person raise their hands (or any other object) into the path of the ceiling fan blades while the fan is in operation. Imagine if some ceiling fan blades moved as fast as an airplane propeller and had blades like a machete! Well, UL standards prevent manufacturers from making such products...but they also present challenges to engineers who attempt design ceiling fans for maximum airflow and efficiency.
Maximum RPMS Allowed for Ceiling Fans
The first basic limitation is that no residential ceiling fans are allowed to be installed such that the blades are less than 7 feet from the floor. The second basic limitation has to do with the RPMs at which a fan can spin relative to the thickness of the blades. The concept is that thinner blades can cause more damage of laceration, so they are not allowed to spin as fast as those with thicker blades.
The RPMs allowed for any residential ceiling fan that can be installed on a ceiling less than 10 feet high are restricted by UL based on the blade span and thickness of the blades (see chart below). Any blade less than 3/16" thick cannot exceed the RPMs for 1/8" thick blades. Any blades 3/16" thick or greater cannot exceed the RPMs for 3/16" thick blades. In no case can the fan blades be less than 1/8" thick. No ceiling fan is allowed to be installed with the blades closer than 7 feet from the floor. These limitations are in place to minimize the risk of injury should a person raise their hands (or any other object) into the path of the fan blades while the fan is in operation.
How do RPMs affect airflow?
The amount of air that a ceiling fan produces is certainly affected by how fast is spins. Yet RPMs alone do not produce airflow. The aerodynamics of the blades is every bit as important as the RPMs. If a fan has blades that are straight and flat, it doesn't matter how fast it spins, it's not going to generate much airflow. Take the same blades and give them a 15 degree pitch and the fan will move air, but the RPMs will be slower since the angled blades are now having to perform some work, which puts drag on the motor. You can equate this to the difficulty of rowing a boat when you place the oars flat in the water compared to turning them at an angle. Flat is easy to row, but will not get you anywhere. Angling the blades just a few degrees makes it more difficult to row the boat, but you actually start moving. So imagine the difference in airflow between 2 fans that operate at the same RPM yet one has flat blades and the other has angled blades. The fan with angled blades must have a more powerful motor in order to maintain the same RPM as the fan with flat blades. So judging the airflow performance of a fan strictly by comparing RPMs is of little value. What you really need to know is how much airflow the fan will produce when operating at a particular RPM.
Maximum RPMS Reference Chart
The data below is based on ceiling fans that have a reverse function. Non-reversing ceiling fans are allowed to have slightly higher RPMs. UL actually states the limitations based on the maximum allowed speed of the tip of the fan blade at 3200 feet/minute for 3/16" thick blades and 2400 feet/minute for 1/8" thick blades. We have provided the following data by creating a formula that does this calculation based on the overall bladespan of any particular ceiling fan ranging from 24" to 84".
Based on UL 507 Standards (link to PDF removed by request of UL - 5/30/2013)
|Span||3/16" Thick||1/8" Thick
Answers to Recent Ceiling Fans Questions Posted To This Page
- Question #9463 - Posted: 3/7/2014 12:32:21 PM
Ceiling Fans Question
QUESTION: room is 18 ft x 28 ft. with a 14 foot vaulted ceiling. What size fan do I buy? How low from the vaulted ceiling does the fan hang? My pendant lights are black...can I use a black fan?
ANSWER: In a room this size of yours, we would most likely recommend 2 fans. Black is certainly a great option if it matches other decorative items in your room. However, there are very few black fans available today, so you may want to consider other finish options in order to dramatically expand your choices. Ultimately, the fan we recommend will be based on many factors including: style, quality, airflow and price range. For that reason, it is best to call and talk to one of our ceiling fan experts in order for us to quickly narrow down your choices over the phone.
- Question #9462 - Posted: 3/7/2014 12:28:41 PM
Ceiling Fans Question
QUESTION: I have a commercial space of 2000 total square feet, but only about 1200 contiguous that needs air circulation for both heat and AC. Ceilings are 12 feet high. I'm thinking 2 fans because the only duct is basically centrally located and kicks air through 3 vents on either side and is about 12 inches from the ceiling. Would you recommend a "commercial" heat fan?! I need a recommendation and would definitely prefer something that is going to be VERY quiet, but also move the air.
ANSWER: Commercial heat fans are typically not designed for quiet operation, so I would probably make a different recommendation for a sound sensitive area. There are so many options to choose from that it is best if you call and talk to one of our ceiling fan experts to go over them with you on the phone. Please call us at: 1-800-201-1193.
- Question #9458 - Posted: 2/23/2014 8:23:35 PM
Ceiling Fans Question - Emerson Model CF788AP
CF788AP - http://www.hansenwholesale.com/ceilingfans/emerson/model.asp?ProdNo=CF788AP
QUESTION: We have a living room with walls that are about 11 feet high with a vaulted ceiling the peak of which is 16 feet above the floor. What height above the floor should the ceiling fan be mounted. We will be using it in the summer for cooling as well as in the winter to bring the warm air down. We havent decided on the fan diameter yet, probably in the 60-72" range. We will most likely be buying an Emererson Eco fan. Thanks.
I would recommend using a 6 foot downrod to bring the fan down a little less than 10 feet from the floor. A 72" Emerson Eco fan should be great for this application if the room is around 15 feet x 15 feet or more. If it is really large, over 20 feet...you should consider using 2 60" fans with 6 foot poles. Below is a link back to the Carrera Grande Eco in Antique Pewter with 72" blades. You can actually select any of the Carrera Grande Eco fans regardless of size and then change the blades that are pictured to any of the 72" blades by clicking on the orange Blades button, so you are not limited to just the brushed nickel finish to create a 72" fan. Carrera Grande Eco 72"
- Question #9457 - Posted: 2/23/2014 8:18:04 PM
Ceiling Fans Question - Fanimation Model FPD8089PW
FPD8089PW - http://www.hansenwholesale.com/ceilingfans/fanimation/model.asp?ProdNo=FPD8089PW
QUESTION: Is there a downrod longer than 72" available for the Fanimation Keistone 72 (DC Motor) Ceiling Fan?
ANSWER: You can purchase a downrod coupler and join 2 downrods together to create a downrod as long as 12 feet. Click on the orange button for Accessories beneath the fan picture on the main product detail page to add the downrod coupler. Then click on the Downrods button to add a downrod. You can then change the quantity to 2 once you add the configuration to the shopping cart. Or just give us a call during normal business hours and we will make sure you get everything you need.
- Question #9456 - Posted: 2/19/2014 2:10:56 AM
Ceiling Fans Question - Fanimation Model FP7910BN
FP7910BN - http://www.hansenwholesale.com/ceilingfans/fanimation/model.asp?ProdNo=FP7910BN
QUESTION: can the Levon Fanimation ceiling fan be installed on a vaulted ceiling? It says it come with a 6" down rod but does not mention any other lengths.
ANSWER: The Fanimation Levon ceiling fan will hang from a vaulted ceiling angled up to 30 degrees using the standard 6" downrod and mounting hardware that is included with the fan. Additional length downrods for ceilings over 9 feet high can be found by clicking on the orange button labeled Downrods, located just beneath the main picture of the fan on the product details page. Ceilings angled more than 30 degrees up to 45 degrees require the optional Angled Ceiling Adapter Model: FA-SCB1-52, which can found by clicking on the orange Accessories button.
- Question #9453 - Posted: 2/11/2014 9:10:42 AM
Ceiling Fans Question
QUESTION: Are your wet rated ceiling fans made with only either plastic or stainless steel interior parts? Could you recommend some which have this?
All outdoor wet rated ceiling fans use special components that are stainless steel or plastic...as this is a requirement in order to be UL listed for use outdoors. With that said, I cannot say that any or all of them use only stainless steel and plastic for ALL components. If corrosion is your concern, I must steer in you in the direction of the Minka Aire Concept I 58" Wet rated ceiling fan which is the first and ONLY ceiling fan where the actual motor housing is made of marine grade stainless steel. This is a new fan that will become available in March of 2014. We are very excited about this great new stainless steel outdoor fan. Each of the finishes the fan is available in are actually applied over stainless steel, so even the white and oil rubbed bronze models are stainless. Here is a link: Minka Are Stainless Steel Concept I 58" Wet Rated Ceiling Fan
- Question #9452 - Posted: 2/11/2014 9:06:07 AM
Ceiling Fans Question
QUESTION: I want to connect a Casablanca fan that takes a threaded down rod to an existing down rod that is .75" OD and is not threaded. Do you carry a coupler or adaptor that will enable me to accomplish this? Thank you.
ANSWER: There is no coupler made to connect a Casablanca ceiling fan to a non-Casablanca downrod. Casablanca does not allow this because they use their own proprietary mounting system that they have tested for safety. Using any other mounting system would void the warranty and could create an unsafe condition, particularly if the previous fan and downrod was not rated for the same weight as the Casablanca fan. You will find this the same with most of the higher quality brands.
- Question #9451 - Posted: 2/1/2014 3:35:37 PM
Ceiling Fans Question - Hunter Model HU-54094
HU-54094 - http://www.hansenwholesale.com/ceilingfans/hunter/model.asp?ProdNo=HU-54094
QUESTION: 54094-hunter Caribbean can you purchase it with a hand remote
ANSWER: You certainly can. Hunter offers several choices for remote controls. Just click on the orange button beneath the main fan picture on the product page to see the choices and add one to your fan. Otherwise, give us a call and we will be happy to help you choose the best control for your needs: 1-800-201-1193