Truth #1: Not all air circulators are the same.
Let’s face it; there is some truth to the old adage, “You get what you pay for”. While the correlation between price and quality is never perfect, there is no magic in making a less expensive air circulator. Often it means taking the design of a good or great product and deciding where money can be saved. It means things like a less efficient propeller; a less expensive motor often with sleeve bearings instead of ball bearings which runs hotter and has a shorter life; reduced thickness of components, a shorter warranty. Do you really believe that a circulator from the big box store which sells for $ 19.95 is the same as $ 600.00 industrial grade circulator? Even Airmaster, the market leader who has been supplying air circulators fans for over 100 years has different grades of product.
Truth #2: Be skeptical of claims of air performance.
There is no standardized test for the air performance of an air circulator. Let me repeat that; there is no standardized test for the air performance of an air circulator which means that it is left to each manufacturer as to how to rate the performance. And at times the “marketing” departments of some companies decide that they have a better idea of performance than the engineering departments!
So, what is a purchaser to do? Look at the amperage for the motor (you can only easily compare units of the same voltage). If the amperage is about the same (and it should be for a given horsepower) but one product has 50% more airflow then something is wrong. Yes, this assumes that the unit will actual operate near the full load of the motor but that is true for most air circulators.
And yes, there are some things that can make an air circulator more efficient than another. Airfoil section blades are generally more efficient than single thickness blades; and special motors can be more efficient than some. Just be skeptical since if it doesn’t seem right it probably isn’t!
Truth #3: Look for air circulators that have been rated by a recognizable agency.
Safety should always be a higher priority than price. Testing agencies like UL or ETL evaluate a product for general and electrical safety so you should be looking for a product that shows that type of rating. Additionally, they periodically inspect the manufacture of the product to assume that what is being produced matches the file information produced during the rating process. Just keep in mind, this mark indicates that the product meets a given safety standard but does not speak to the performance of the unit.
Truth #4: Stiffness / Material Thickness & How it affects Vibration / Longevity
Why do some air circulators shake? Why do some start to shake with just a little build-up of dirt on the impeller? A couple of things you need to know; there is no such thing as a perfectly balanced propeller – there is always some amount of residual imbalance which creates a force trying to move things. Second, think about a spring with a weight at the end. If it is a thin light spring (think the old-time springs on screen doors) then when you stretch the spring out and let it go, the weight on the end will bounce quite a lot. Now think about a heavy spring (car spring) stretching it (if you can), let go and it doesn’t hardly move. The same is true for air circulators! If the supporting parts (from the impeller to the ground) are light weight and hence not very stiff then you are going to get a lot of movement for a small amount of force. Heavier parts (and better design) will increase the stiffness reducing the vibration and / or the resistance to vibration as dust builds on the impeller. Takeaway is if you want an air circulator that will run a long time without shaking look for one that is of heavier construction.