KNOXVILLE, Tenn. — Building a 25- by 75-foot in-ground concrete swimming pool is a difficult enough task without having to put one in a former retail store of a shopping center.

But that is what the Rush Fitness Complex ordered from its engineering and consulting team when it chose a former 37,000-square-foot department store in the Walker Springs Plaza shopping center for its second location.

The $200,000 pool was a key part of the $2 million construction project. “Baby boomers want more than just weight lifting from today’s health clubs,” said co-founder Larry Gurney. “So it was important for Rush to have a pool in one of its two Knoxville locations.”

Most developers of such projects acknowledge that pools tend to be problematic as far as odor and humidity infiltration into the rest of the complex. The problem is accentuated with existing building retrofits because the original structure’s design doesn’t have pool architectural necessities such as heavy insulation on outside walls, proper building pressurization, or a vapor barrier surrounding the pool area.

Therefore, dehumidification and airflow were important elements of Rush Fitness’ 4,000-square-foot pool room. Consulting engineer Rusty Whillock of Engineering Services Group of Knoxville anchored his design around a Dry-O-Tron® DS-080 heat recovery dehumidifier by Dectron Internationale, Roswell, Ga., and fabric duct air dispersion by DuctSox®, Dubuque, Iowa.

The dehumidifier not only dehumidifies the space at a capacity of 80 pounds of moisture/hour, but also cools or heats it to an 80 degree F setpoint and recovers compressor heat to provide 78 degrees F pool water temperature. IAQ is monitored by the Dry-O-Tron on-board microprocessor.

Critical in the design was Whillock’s moisture load calculations, which are affected by the evaporation rate of the pool and the 55-square-foot, 105 degree F whirlpool. Usage, which was determined to be mostly exercise, was considered moderate compared to heavy usage at more conventional recreational pools.

Architect Daryl Johnson of Johnson Architecture, Knoxville, ensured the existing metal roof and supports would never be subjected to humidity by specifying an airtight vapor barrier around the entire pool enclosure. Additionally, the pool room walls were built of moisture-resistant cement board and an anti-corrosion coating was applied to all nearby metal surfaces.

Johnson also created a two-foot-high buffering air zone between the pool room ceiling and the building’s exposed bar joists and steel roof as an extra precaution against condensation.

Whillock added to the IAQ effort with the fabric duct air dispersion, which runs along the perimeter of the 14-foot-high pool room and broadcasts dry, conditioned air along the walls. Those involved in the project said that the use of fabric duct is a good choice in aquatic environments because it is corrosion resistant and tight.

Whillock designed the room with negative pressurization to prevent any excess humidity or pool chemical smells from escaping to the other fitness areas. This was made possible by an exhaust fan that’s placed over the highly evaporative whirlpool.

In constructing the pool, Rouse Construction of Knoxville and pool builder Pools by Bill, also of Knoxville, cut a 4-inch-thick concrete slab, preserving the existing 5-foot-square footers sustaining the building’s support columns. The 35-foot distance between support columns dictated the pool’s width at 25 feet.

General heating and air conditioning is provided by rooftop units from Trane, Tyler, Texas.

Publication date: 01/13/2003