"But the cost to humidify the building was escalating, not only because of electric rates, but also because the electric canister-type humidification system required frequent maintenance and canister replacement due to hard water conditions," said Jim Bender, P.E., with HTS Engineering. The firm helped the Waterloo facility specify a new system.

Working with Union Gas Limited of Ontario, a gas utility which funded an energy cost study, Bechtel installed an energy-efficient, gas-to-steam humidification system. With an 80% efficiency rating, the Dri-Steem GTS(r) humidifier cost only $2,500 to run over a 14-month period, compared to over $7,000 for the electric system, according to the study conducted by Culham and Associates, consulting engineers, Mississauga, Ontario, Canada. "These figures reflect what many of our customers are discovering," said Bender. "More and more, customers are investigating their options with gas."

Why Humidify?

At the Waterloo testing facility, which monitors, samples, and tests the area water supply, humidification is critically important because specific room temperatures and humidity levels are a requirement for certification of the two laboratories, one for organic testing, the other for inorganic testing. AHUs supply 100% fresh air to the labs - 11,500 cfm - and, especially during the cold months, this fresh air must be humidified to required levels.

Humidification is also important for the 35 people who work there. Not only does humid air feel warmer to occupants, but without proper humidification, the air in a typical commercial building can dry to rh levels below that of the Sahara Desert. Low humidity causes nasal and throat membranes to dry and increases susceptibility to colds and viral infections.

Maintaining 40% to 60% rh improves IAQ by decreasing bacteria and viruses in the air (a factor when humidity levels are below 40% rh), and hindering the development of fungi, chemical interactions, and ozone production (more prevalent when levels are above 60% rh).

Until recently, most small- to- medium-sized office buildings were humidified with disposable, canister-type electric humidifiers. Electrodes in a water container generate steam that is distributed throughout the building by the HVAC system. These humidifiers can require frequent maintenance when the canister becomes filled with mineral deposits. Waterloo's water supply contains significant levels of lime and calcium, and the canisters required frequent changeout.

Evaporating Maintenance Costs

Installed in the mechanical room, the GTS humidifier uses multiple, low-nitrogen oxide (NOx) burners to heat the water in the evaporating chamber to produce steam. Steam created in the evaporating chamber flows through the steam hose or piping into the dispersion assembly located in the AHUs, where it is discharged into the airstream. The products of combustion are exhausted out the flue.

Designed to work with any type of water - tap, softened, or deionized/reverse osmosis - and regardless of water hardness, the GTS is designed for easy maintenance. The Vapor-Logic(r)3 controller can be programmed to monitor and regulate all functions, including a drain-and-flush cycle. Plus, the heat exchanger continuously sheds mineral buildup due to constant thermal expansion and contraction, and a water skimmer removes floating minerals. The 304 stainless steel humidifier includes two-sided access so all components are within easy reach, including a removable cleanout plate to remove tank sediment.

With proper humidification, employees at the testing facility can work more comfortably to help deliver an important service to the residents of Waterloo.ES