Centrifugal fans consist of a central shaft with one type of curved blades arranged around it. These fans blow air at right angles to the intake of the fan, and spin the air outwards to the outlet. In other words, when air exits the fan, it exits in an outward-angled fashion (like a cone). If ducting were on the end of this fan, air would be pushed into the walls of the ducting more than it would be pushed through the center.
These are low-volume and high-pressure fans.
Mixed-flow fans, like the Can Max Fan, have two types of blades on a central shaft. One of these blades is a rotor blade, and the other blade makes the air come out like a beam instead of the cone shape found in centrifugal fans.
Moreover, these fans integrate two specific design methods to make them more efficient: One method moves air by creating a pressure differential (imagine being on an airplane and someone opens the door – all of the high pressure air inside the cabin naturally rushes to the low-pressure environment outside the craft). In the second method, the blades are literally hitting the air and causing it to move in a certain direction.
Max fan’s incorporation of air wanting to go from a high to low pressure environment means it naturally uses much less energy than its counterparts. For example, the Can Fan 6” (centrifugal) uses 125 watts at 265 cfm. The Vortex Fan 6” uses 130 watts at 450 cfm. The Can Max Fan 6” uses only 66 watts to deliver 422 CFM.
Apply this to real life applications -what happens when we add on an appropriately sized carbon filter? Centrifugal fans tend to lose 20-25% of their air flow (including Vortex) and Chinese-made fans will suffer up to a 40% loss of air flow. This means your 450 cfm Vortex Fan with a 25% loss of air flow goes from 450 cfm to 325 cfm (while still pulling 130 watts).
Mixed Flow fans rarely see more than a 10% loss in air flow. A fan like the Max Fan Pro 6” at 422 cfm goes down to 380 cfm (while still pulling only 66 watts).
Check out our video comparison:
David says
Excellent write-up. You sold me on mixed-flow fans in a duct!
Centrifugal Fans says
It is indeed interesting to note how versatile mix flow fans can be. But I think centrifugal fans can never lose their value in cases where only single modes of operation are required. https://nisco.ca/category/products/centrifugal-fans-and-blowers/