"In the light commercial market, there have been very few dedicated products available to satisfy a building's need for humidification," said Gene Curtis, light commercial channel manager for Aprilaire. "Contractors have been forced to either apply multiple residential units or expensive to service canister humidifiers. In many cases the contractor had to supply a commercial/industrial product that was overkill from both the application and price standpoint."

Aprilaire is touting two new design features incorporated into these light commercial models. The Aprilaire Steam Humidifier Model 1150 is a 12-lb/hr unit that features a simple "on/off" control. The Model 1160 is 24-lb/hr unit that features a modulating output that regulates the output of the humidifier based on the humidity needs of the building.

Designed with the light commercial contractor's needs in mind, the units feature installation flexibility, thanks to short absorption distances allowing installation in tight duct configurations. Continuous electronic monitoring of the water level and compatibility with both softened and tap water minimize any water supply problems. The steam chamber's stainless steel design, with welded seams, is meant to require minimal maintenance. The stainless steel frame and housing are also intended to exceed all application requirements and work well in any environment.

Finally, Aprilaire emphasizes that each steam humidifier comes complete and ready to install. The unit includes a steam humidifier control, airflow proving switch, steam distribution tube, and 10 feet of flexible steam hose.

DRISTEEM also checks in with a new product, the VT Series electric humidifier for both light commercial and residential applications. The unit is designed so that the user can just set the humidistat, press the "on" button, and walk away. When softened water is used, says the company, the VT Series can be maintenance-free for three or more years. Meant to complement any finished space and make for easy installation, the VT Series also electronically monitors water level and works with either softened or tap water.

The unit offers a capacity range of up to 48 lb/hr, and it features a removable, lightweight shroud that allows easy access to tank, water level control assembly, and electrical connections. A controller-operated drain-and-flush process removes precipitated minerals from the tank, while constant thermal expansion and contraction of heating elements is designed to allow continuous shedding of mineral buildup.

DRISTEEM has also completed a redesign of its GTS gas-to-steam humidifier. Streamlined configuration places all components in the cabinet, simplifying installation and maintenance. New features include only two-sided access required, and one convenient removable panel leading to access for wiring, water level, and clean out. Integral water tempering, easier connections, and a more aesthetic design are also among the improvements, says the manufacturer.

Among the latest releases from Herrmidifier (a division of Fedders Engineered Products) is its range of Herricane® CS steam distribution systems. This series of products meters steam from central boilers, humidifiers, or unfired boilers in commercial environments. According to the company, its metered nozzle technology design extends into the steam manifold, allowing the driest steam to discharge evenly across the entire length of the manifold.

Herrmidifier's Rob Clemens said this is important since otherwise, "there can be as much as 50% differential in humidity from one side of the air handler/duct to the other. If the wrong side is chosen for a control location, severe wetting of the air handler/duct may occur."

The company lists other key features of its new series to include pre-shipment of testing units; the ability to empty steam from a central boiler, humidifier, or unfired boiler; capacities to 2,000 lb/hr; stainless steel precision nozzles; quiet operation; and guaranteed evaporative distances.

Based on application conditions, the Herricane CS Series is meant to eliminate guesswork by posting specific evaporative distances, heat gain, and pressure gain. The manufacturer points out that in addition to maintenance-free operation, the series "allows full accessibility to the in-duct insulation so that one can easily see when service is required."

Meanwhile, Nortec's NHSC incorporates a new, patented scale management system to deal with extreme water conditions. The flexible inner liner of the humidifier allows scale to easily break off and fall into the scale collector tank at the base of the unit. During mid-season cleaning, users can remove the tank when the unit signals, dump the sludge, remount the tanks, and continue. With no tools required for this process, what used to take hours of hard labor can now take just minutes, according to the manufacturer.

The NHSC also includes features familiar from previous Nortec products. These include full-function display, full modulation control with solid state relays, and a heavy-duty drain pump.

Nortec's other focus is on the new generation of its SETC steam exchange humidifiers, suited for facilities where steam pressure is available from a boiler. The boiler steam passes through the SETC internal heat exchanger, bringing the surrounding water in the tank to atmospheric clean steam vapor. Thus, the company points out, the chemical treatment from the boiler does not enter the airstream.

Standard features include the company's own internal drain water cooler to meet local plumbing codes, a scale management system, a flat-surface heat exchanger for easy maintenance, and up to 1,500 lb/hr of steam production from a single unit. Additionally, the SETC with Nortec's Total Controller will interact with most popular protocols including BACnet and LonWorks, according to the manufacturer.

Elsewhere in the realm of moisture control, Vaisala offers its Series HMT330 group of HUMICAP® humidity and temperature transmitters. Created to be the top of the line for demanding industrial applications, it's built on Vaisala's established HUMICAP technology for providing reliable measurements. The chemical purge function is provided to maintain accuracy when dealing with high concentrations of chemicals, while the warmed sensor head (available for the HMT337) provides true humidity readings in condensed conditions, according to the manufacturer.

A large display shows measurements both numerically and graphically, and a one-year history is also available, simplifying the process of monitoring measurement trends. Furthermore, users can adjust the interface to any of seven languages - English, Spanish, French, German, Japanese, Swedish, and Finnish.

The HMT330 Series comprises six models, tailored for different applications depending on placement on walls or tighter spaces, or in environments featuring extreme temperatures, humidity levels, or pressurized processes. ES

The ES Humidification Bookshelf

Humidification: Side By Side By Michael Kjelgaard, P.E. Kjelgaard makes a practical and operational comparison between the two types by simulating an isothermal humidifier and an adiabatic-type humidifier in the same air-handling system. Several different geographical locations are considered to evaluate the impact of the local climate as well as local utility costs.

Ultrasonic Humidification Is Ultra-Efficient By Joanna Turpin Ultrasonic humidification, which is an adiabatic type of system, is just one of the methods available. These systems are known for using very little energy, and experts state that they also provide high-quality moisture and close control of an environment while requiring little maintenance. However, other factors such as first cost and water quality also have to be considered when figuring out how an ultrasonic humidifier will affect a building's total operating costs.

Humidification 101 By Gene C. Nelson, P.E. With the advent of IAQ issues, humidification has become an important part of providing acceptable indoor environments, especially in northern climates. Successful humidification system design depends on understanding the science of humidification and developing the "art" of proper application. This article includes a general discussion of design criteria, building envelopes, load calculations, system selection, equipment selection, and equipment installation.

Commissioning Building Humidification Systems By Ron Wilkinson, P.E. As an integral part of the HVAC system and its controls, the humidity control system must be tested in conjunction with other parts of the overall HVAC system. This article will address the commissioning of humidification systems from planning through design checking. This includes documenting the humidification requirements of the building, checking the design to confirm the selection of an appropriate system, and writing the specifications for the testing of the systems during construction.