Don’t be Fooled by Horsepower! It is NOT horsepower you need from a PPV Fan. It is AIR VOLUME.
Adding horsepower to a ppv fan increases CO output, noise, weight, expense, etc, but does not always increase air volume because there is a diminishing point of return given the length and design of a propeller. After a certain point, you can add horsepower, but get no additional volume in return. It is extremely important when comparing ppv fans that you compare performance (air volume and thrust), not just assume higher horsepower is better.
Most VENTRY Fans use the same brand of engines as common box fans (Honda, of course), but utilize smaller models (less horsepower). VENTRY Fans use from our 1.5 hp electric to 5.5 hp gas. Other manufactures offer motors as large as 11 horsepower on fans with short propellers (16-20 inches)! There is little return in terms of air volume. We have even seen 13 hp motors on fans with 24-inch long blades!
The longer the propeller... the more efficient it should be. This makes the fan bigger, however, and very few of our customers have the storage space or extra manpower necessary for fans that are larger than our 24GX200 (24-inch prop and 5.5 hp) motor. For maximum air volume and versatility, we recommend multiple smaller fans.
Excess horsepower is often used to compensate for poor propeller design. We believe this reduces the value of the product. While CFM might increase slightly with higher horsepower, so does the price while ease of operation decreases. Our fans use the highest horsepower motors that 20- and 24-inch Safety Propellers can utilize. Our Safety Propellers are designed to utilize the full power of each specific motor to realize the maximum air volume. VENTRY Fans push a lot of air even though the motors are relatively smaller.
When comparing fans, be sure to consider efficiency. Simply divide the CFM by the horsepower of the fan motor. This will show you how much air you get per horse, so to speak.
Physical laws of nature limit the amount of horsepower you can efficiently absorb relative to propeller disc area. This is analogous to the limitations on drafting water through a 2-inch suction line. Regardless of how much horsepower you hook up to that suction hose, atmospheric pressure and friction losses limit how much water you are going to move. The same principals apply to moving air. Increasing horsepower without increasing the prop disc area actually creates more noise and stirs the air instead of pushes it. That painful racket you hear coming from oversized engines hooked to inefficient propellers is the sound of inefficiency.
TRUE STORY: Hot air balloon pilot Ken Manning has been pleased with the performance of his 24-inch GX160 VENTRY Fan, which he uses for inflation. He told us that a friend of his, also a balloonist, had asked him what size fan he purchased.
When told it was a 5.5 horsepower model (now rated only 4.8 hp), the friend asked, “Why so small? What brand is it?”
“A VENTRY,” Ken had responded.
“Oh,” said the friend, “Then that’s no problem.”