# Forum Home Renovation Heating & Cooling  New ceiling fans - very slow

## renonewbie

Hi, I replaced all the efficient yet seriously nicotine-stained metal ceiling fans in my new home with modern looking 3 blade fans (wooden blades).  An electrician installed them and I have to say... I am really disappointed in the results.   
All of the fans are the same brand, and were a simple replacement with the old fans.  I only ever use the highest setting as anything else would not likely blow out a birthday candle! Pathetic amount of air movement being generated.  THere is one that works 'properly' on highest setting (at a speed I would expect) but the other 2 speeds are pathetic. 
I know that there is a difference based on blade angle/direction but the sparkie said he was careful to keep it on 'summer' season (I live in Cairns so 'summer' is great for all year round!) and as I didn't read the instructions myself, I've taken his word for this.  Any suggestions? DO you think they are dodgy fans or should I do something to the blades to make them work more effectively?  Why is the highest setting so variable between all 6 fans?  Why is the 2nd and 3rd speeds crappy on all fans?   
It was a hot old day today, and I am sick of having to use ceiling fans as well as pedestal fans!

----------


## SilentButDeadly

If you bought them from anything other than a ligthing or fan specialist then I would suspect you bought cheap and got a box of lemons in the process.  If you have the reciepts and warranty info then give the manufacturer a yell and seek a please explain.  But it may be easier to simplyinvest in some metal bladed Hunter Pacific fans Hunter Pacific International which'll set you back around $150 but will last and perform in your environment. 
You can't do anything with the blades - the summer/winter switch simply reverses the motor.

----------


## jago

As per SBD post.  
Have you looked at Big Ass Fans google them ...

----------


## Danny

Hi renonewbie,   

> I replaced all the efficient yet seriously nicotine-stained metal  ceiling fans in my new home with modern looking 3 blade fans (wooden  blades).

  Are they flat rattan blades? If so, the blades will generate a lot of inefficient pressure drag and turbulence. Fan blades are aerodynamic devices that need to be designed with a smooth surface and blades with a curved cross section are more efficient than flat blades. 
Most 3 blade designs also have wide blades which in turn create a lot of pressure drag. It is best to have narrower 4 or 5 blades. These give a higher swept solidity ratio and less drag for greater operational efficiency.  
Jago mentioned Big Ass Fans. These fans are aerodynamically designed with multiple narrow blades that are also end plated. Their website is well worth a visit. Fan blades generate most of their 'thrust' from the end 30% of their length but roughly 15% of this is lost to 'spillage' if not end plated. Unfortunately, most domestic fans are designed for visual appeal at point of sale rather than operational efficiency.  
A major influence governing a ceiling fan's efficiency is the air gap between the blades and the upper boundary layer (ceiling). The minimum gap needs to be 500 mm, anything less than this will compromise efficiency due to the restricted aerodynamic draw down.  
Also check the fan's rake, a positive rake will concentrate the throw whereas a neutral rake will give a broader throw but over a shorter distance. 
An efficient fan should still be effective at lower speed settings; Do the instructions state the design air volume moved (cubic metres per minute) for each speed setting?

----------


## Boeing777

Whatever you do, don't google image big ass fans, very different results!

----------


## jago

Very odd your browser must have some cookies from elsewhere  for those with a dodgy browser history lol Industrial Ceiling Fans - Big Ass Fans

----------


## Lawrst

Someone has safe search off  :Wink:

----------


## SilentButDeadly

That Element fan is a beauty  ELEMENT

----------


## Wombat2

I recently had a fan installed in our rental when the old one spat the dummy- I bought a new one and used that at home and the one from home I had the electritian install in the rental - he said the speed controller didn't match the replacement and it would only run with not much variation between speeds - haven't seen it myself and the tenants haven't complained but the new one at home runs OK on the old speed controller.

----------

