Vertical temperature difference ranged from 5F to 30F.
New Hampton Metal Fab, based in New Hampton, IA, has reinvented itself several times over. From its roots as a blacksmith shop housed in a 20 x 40-ft. shed, it now resides in a 53,000 sq. ft. facility, precasting molds for agriculture and government equipment, along with recreational and local industries.
The larger facility, while good for a growing business, posed some unforeseen comfort roblems. All the heat was rising to the rafters, 40-ft. above the work floor. Installing a large diameter, low speed ceiling fan to circulate the air not only improved worker’s conditions but significantly reduced heating costs for New Hampton.
“We’d send somebody up to fix something and they’d strip down to their long johns,” says Pete Gallup, purchasing manager. “The guys on the floor are standing there in Carhartt jackets, basically freezing to death. We knew something needed to be done.”
Heat Rises and Escapes
Stratification occurs because hot air is less dense than cold air. The air coming out of a heating system (or in the case of some manufacturing facilities where this heat is produced from the equipment itself), is approximately 5-7% lighter than the air in the space, collecting at the ceiling. This results in a significant vertical temperature difference from 5 to 30 F. With winter temperatures averaging 22F, and much of the warm air in the building simply wasted at the roof line, New Hampton installed an 18-ft. diameter Big Ass Fan® to help destratify the air in the newest area, an addition to the warehouse, and maintain an average temperature of 68F.
The Spin of Destratification
Large diameter fans are capable of destratifying this air, reducing energy consumption by as much as 30%. Instead of reversing the fan, a Big Ass Fan — ranging in size from 8-24-ft. in diameter — is simply slowed to 15-25% of its maximum operating speed, without a draft. Through proper air circulation the warm air is pulled off the ceiling and brought down to the occupant level before escaping through the walls and roof.
“Even though the thermostat setpoint remains the same in the winter, the heating system does not have to work as hard to maintain the given setpoint,” says Christian Taber, senior applications engineer and LEED AP for Big Ass Fans. “By reducing the amount of heat escaping through the roof, it’s similar to turning the thermostat down five to seven degrees.”
To this extent, Gallup says, New Hampton saved 34% in heating costs after the fan was installed. “We used to have some very cold corners we just kind of moved away from. Nobody would work there,” Gallup says. “Now anybody can work pretty much anywhere. It destratifies the air so well that it’s uniform all the way up.”
Also a Condensation Solution
For facilities that have to deal with condensation build-up, the addition of constant, steady air movement produced by large diameter, low speed fans speeds the evaporation rate of the moisture on the metal’s surface by one-third. It may take hours or even days for the temperature of the delivered product to approach the inside air temperature. During this warm-up period, the metal’s surface temperature is initially below the dew point temperature of the air, leading to condensation on the surface of the metal and potential corrosion. Decreasing the time in which corrosion has to form in turn saves construction material.