One of the most important factors to consider when selecting a fan system for your food manufacturing center is the size of the facility. A variety of fans - from box fans to centrifugal fans - are available for consideration, however, these fans are not capable of efficiently handling the cooling and ventilation needs of most high-ceilinged and large open interior spaces.
High Volume Low Speed fans are large-diameter fans that evolved out of the need for greater air movement to meet the ventilation and circulation requirements of large spaces, such as food manufacturing and storage facilities. Unlike small fans that cool only a limited area directly in front of each fan, High Volume Low Speed fans blanket a large area with constantly moving air to create an expansive comfort zone. By using only one fan to do the job of a dozen or so small fans, energy and cost savings are seen immediately.
Fans designed for efficiency
High Volume Low Speed fan systems emerged in the late 1990s and take advantage of the physics of fluid dynamics, NASA-inspired airfoil designs, and the latest manufacturing technologies. The ten-bladed ceiling fans create a continuous flow of air that is supported by an engineered air movement system.
The typical industrial High Volume Low Speed fan system is 20 feet or 24 feet in diameter. The blades are easily bolted to a cast aluminum hub. With their large diameters, these fans create large columns of air that have proportionally less area of periphery and therefore less friction and related drag. This allows the air column to move farther using less energy and effort than smaller fans (a 36 inch fan has over six times the "friction interface" of a 20 foot fan).
The power unit is comprised of a one or two horsepower motor specifically matched with a gear reducer. A single motor control panel with variable frequency drive allows for blade speed adjustment, including reverse average air speeds range from three to seven mph for a fan with a one horsepower engine and five to nine mph for a fan with a 1.5 horsepower engine.
Energy efficiency is fundamental to the design of High Volume Low Speed fans because the power required to drive a fan varies in relation to the cube of the average air speed through the fan. For instance, a fan delivering air at 20 mph requires 64 times as much power as one delivering air at five mph. Moving more air at a slower pace and with larger blades rather than larger motors is key to the power of these fans. The momentum of circulation of the large air mass requires little ongoing effort to maintain its circulation, so a large motor is not needed.
Operating one High Volume Low Speed fan costs about a nickel per hour, paying for itself over time by keeping energy costs low.
Benefits to your business
When replacing up to 25 standard industrial fans in a large facility, High Volume Low Speed fan systems can provide all the breeze necessary for an evaporative cooling effect of six to eight degrees, resulting in a more comfortable work environment and increased productivity. Throughout the year, High Volume Low Speed fans can be used alone or in tandem with A/C or heating systems. When used with A/C systems, the fans distribute the air and allow thermostats to be kept on a higher temperature setting, producing less A/C output and significant energy savings. During heating seasons, the fans improve comfort by bringing trapped warm air from the ceiling down to floor level. Temperature differences of 15 degrees or more from floor to ceiling are common in the absence of the fans. With the destratification of heated air in a facility, thermostats can be kept at a lower temperature setting, producing less heat output and significant energy savings (20% and greater).
The fan's massive air mixing also results in greater absorption and dispersion of noxious fumes and damaging moisture and humidity, resulting in a healthier, drier, and safer environment. Other benefits include elimination of birds and bugs, as well as avoiding the noise and disruption that would be present if other air flow solutions were in place. Periodic maintenance of the High Volume Low Speed fans involves cleaning of the anodized blades, minor lubrication of components, limited bolt tightening, and inspection of built-in safety features.
When using High Volume Low Speed fans as a solution for heat destratification or as a supplement to A/C, rapid payback, high return on investment (ROI), and significant net present value (NPV) are realizable. For example, one recent installation analysis projected annual heat savings of 40% with a payback period of 1.4 years, a two year ROI of over 40%, and an NPV based on only five years, at a high discount rate, in excess of $100,000. The analysis demonstrated that this facility was spending too much money on energy, money that could be spent on other areas of the business. For food manufacturing facilities, the fan systems also help to realize additional cost savings through the prevention of food spoilage and moisture build-up.