Large, oversized ceiling fans have been touted as the latest technology breakthrough in the air-movement industry. They are energy efficient and move large volumes of air, and they can be effective in some work environments to provide space and comfort cooling. For equipment cooling and other process cooling applications, a hybrid fan that incorporates a “gill” into the traditionally solid housing of a modified tubeaxial design might provide a better solution.
The primary benefits of gill-based hybrid fans are reduced amp draw and noise levels. Experimentation has shown that the gill-based hybrid fan design allows more air to enter the fan housing compared to conventional cage-style or tubeaxial fans. The additional air provides users with equal fan performance while reducing amp draw by approximately 1 A (16 percent). The gill also lowers noise levels by 2 to 3 dBA.
The reduced amp draw of the fans is noteworthy when considering that companies across the United States are enacting “green initiatives” to save energy and reduce environmental impact. Motors of less than 1 hp are not subject to premium efficiency standards as are higher horsepower motors. Most hybrid fans are fractional horsepower fans and fall outside of the regulations and oversight affecting larger fans.
Consider the following when comparing hybrid fans with conventional cage-style or tubeaxial fans for process cooling applications:
velocities result in faster cooling, which can increase productivity
- Longer air throws might reduce the number of fans required.
- Mounting options are greatly increased due to the variety of mounts,
sizes and air throw distances of hybrid fans.
- Directional air throw gives greater flexibility in controlling the
amount of air hitting equipment or products. This enhanced operation allows for
better control of cooling rates.
- Hybrid fans may be more energy efficient (see sidebar “Energy
In summary, when evaluating fans for process cooling applications, keep these three thoughts in mind. First, remember that high-velocity fans are easy to work with due to their light weight and compact size. Take advantage of this benefit to experiment with fan placement. Start with a size that fits comfortably into the area where the fan will be used, and move up or down in size as needed.
Secondly, evaluate the power requirements. Many times, larger horsepower fans with a higher voltage motor make economical sense. Finally, remember to compare long-term operating and maintenance costs as well as acquisition and installation costs. Short-term savings often can be quickly eaten up by long-term costs.
Sidebar:How can 0.9 A reductions in electrical requirements on gill-based hybrid
fans vs. conventional tubeaxial fans affect “green” goals? A simple example is 25,000
fans x 250 days x 10 hr/day x [(0.9 amps x 115 volts)/1000] = 6,468,750 kW/yr.
Energy Efficiency Comparison
Hybrid Fan Specifications
5.1 A x 115 V = 586.5 W
586.5 W/1,000 = 0.5865 kW
0.5865 kW x $0.10/kWH = 0.05865
0.05865 x 10 hr/day x 250 days/yr = $146.625/yr/fan
100 fans x $146.625 = $14,662.50 operating costs
3 to 4 fans/20 A breaker = 25 to 34 breakers
Field-Tested Conventional Tubeaxial Fan Specifications
6.9 A x 115 V = 793.5 W
793.5 W/1,000 = 0.7935 kW
0.7935 kW x $0.10/kWH = 0.07935
0.07935 x 10 hr/day x 250 days/yr = $198.375/yr/fan
100 fans x $198.375 = $19,837.50 operating costs
2 to 3 fans/20 A breaker = 34 to 50 breakers
Savings = $5,175/yr operating costs
Note: Additional savings could come from eliminating the need for up to 16 20-A breakers on new installations or freeing electrical capacity in existing applications.
Source: In-house testing by Patterson Fan