Frequently Asked Questions

At what speed am I going to want to run the fans?

ASHRAE standards suggest that air movement of 40 feet per minute (fpm), or less, is difficult to detect and is very comfortable. At their maximum prescribed height, the terminal velocity of the air column produced by ZOO Fans falls above this range, in the slightly more noticeable, yet still quite comfortable range of 80-100 fpm. ASHRAE standards suggest an upper limit of 160 fpm for people who are lightly clothed, performing primarily sedentary activities. For intermediary ceilings heights or to adjust for localized conditions or comfort, simply adjust the speed of the fan.


Can ZOO Fans help me earn LEED Credits?

YES!  Significantly reduce the use of ducting on new construction, save energy and reduce operating costs.  Please review our LEEDS page to see how.


When Destratification Fans are specified for a job, can the engineers and contractors have confidence that ZOO fans will perform as claimed?

Don’t just take our word for it! Performance numbers for our fans were provided by third-party testing in Europe, the INVENT center at Ziehl-Abegg in Künzelsau, Germany. Unlike others, ZOO Fans’ performance ratings are not derived from amateur observation. They are also much more than the simple repetition of the specifications of the underlying motor. ZOO Fans technical information takes into account a critical component in overall performance – the effect of the fan housing. Narrowing tailpipes, fins and stators can significantly reduce air flow – with ZOO Fans’ patented design and third-party performance testing, you can be confident our fans will perform as specified.


Why not just run the fans when the building is occupied?

Destratifying an air mass consumes more energy than simply maintaining equilibrium once it is achieved. If you are managing the speed of the fans with BMS, setting the temperature differential between floor and ceiling as the driver for fan speed is one way to effectively manage their operation. Alternatively, run the fans on full to determine the minimum temperature differential that can be achieved, then continue to turn the fans down until you reach the minimum speed that will maintain this differential—then “set ‘em and forget ‘em!”

Again, the key is to maintain temperature equilibrium as closely as possible—this will yield the greatest creature comfort and the greatest HVAC savings. Instead of turning them up and down, running the fans constantly at a lower speed will lower the operating costs of the ZOO Fans themselves without impacting performance.

For example, a fan running at 2/3 speed generates 2/3 the CFM but consumes only 1/2 the power. A fan operating at 1/2 speed consumes only 1/3 the power. Another way of looking at it is that running a fan 24/7 at 2/3 speed consumes the same energy as running it for 12 hours on full power. And running a fan at 1/2 speed 24/7 is the same as running it for 8 hours on full power.


Just how efficient and economical are ZOO Fans to operate?

An H30 at 2/3 speed costs less to operate than a 25-watt light bulb; at 1/2 speed, it consumes 18 watts. An H60 at 2/3 speed costs the same as a 50-watt light bulb; at 1/2 speed, it consumes 34 watts. For more detailed data, see the Specification Sheet under the “Our Products” tab.


The building has radiant heat, so why would I want destratification fans?

Radiant heaters end up heating something that re-radiates that heat. In addition, the heaters themselves generate quite a bit of heat. And much of it ends up at the ceiling.

In a tube heater, the radiant heat is produced by a steel tube (length from 10-70 feet) that is heated to temperatures ranging from 350-1050°F; in a luminous (high intensity) heater, the radiant heat is produced by a ceramic surface (comprised of varying numbers of ceramic tiles) at 1750°F. Note that infrared heaters are also often called ‘radiant’ heaters.

The infrared energy is absorbed by the floor and objects at floor level, including occupants, all of which become warm and, in turn, heat the air in the building. And they continue to release heat to the air, even after the infrared heaters are turned off. There could be significant differences in the infrared output, based on the burner material, configuration, operating temperature, mounting angles, combustion air input and reflector design. On average, more than 50% of the heat generated by infrared heaters is convection heat, and in some inferior models the percentage of convection heat is as high as 65%. ZOO Fans return this otherwise wasted heat down to the floor, allowing radiant systems to run less, eliminating the hot and cold spots, and increasing thermal comfort.

Case study: A Ford dealer in Lexington, KY installed ZOO Fans in their drive-through service area last winter, where they have radiant heat. (You can see a picture of the installation under the “Gallery” tab on our website.) Customers and employees immediately commented that it was noticeably more comfortable. The service manager reported drier floors, happier employees and savings of 25-30% on his heating bill. Regardless of how the space is conditioned, any conditioned space will be more economical to heat or cool when it’s destratified!


I understand the value of bringing heat down in the winter, but what’s the point of mixing that warmer air in the summer?

Great question. Bringing air down from the ceiling during cold weather is intuitive because we all know that heat rises. The benefits of bringing cold, conditioned air to the floor during warm weather, reducing the introduction of hot make-up air, and maintaining overall circulation are well-known to HVAC technicians and engineers in hot-weather climates. Many commercial systems bring the A/C into the building at the ceiling and, depending on the design, rely on the air handler to: 1) push the cool air to the floor, often creating drafts and hot-and-cold spots, or 2) flood the upper reaches with cool air that’s supposed to drop to the floor. In fact, unless this cold, conditioned air is pushed downward, it will stall and gradually exchange its cooler, drier characteristics with those of the warmer, moister air mass. We’ve all experienced what happens in a movie theater: it’s cold when the A/C is running, hot and stuffy when it’s not. With ZOO Fans, the air handlers run less, there is less hot make-up air introduced to the system, and the air keeps moving!


Why ZOO Fans instead of traditional ceiling fans, or even a big fan? Don’t they do the same thing?

One way to think about mixing air in a large space it is to relate it to mixing water in a swimming pool. Older pools used to use just one or two points-of-entry for introducing heated water, and you could always tell where they were because people were gathered around them when the water was cold. Modern pool designs call for a number of small diffusers spread over the bottom of the pool. Why? Because it is usually more effective to utilize a larger number of smaller, more efficient mixing points than it is to use one or two big ones. Tornados would be an obvious exception!

In addition, many installations have overhead obstructions that make it impossible to install a big fan, or perhaps the aesthetics of a large ceiling fan don’t fit with the building’s design. That said, if a space is non-conditioned, there are no overhead obstructions, and wind speed is not an issue in your facility paddle fans can be an effective way to provide evaporative cooling. For spot cooling—to provide localized evaporative cooling to a specific work area or to dissipate heat from localized operations—ZOO Fans can be an ideal solution.