The whole-home humidifier marketplace continues to be an integral slice of the HVAC industry. Evaporative, warm-air steam, and ultrasonic humidifiers are highly desirable for customers coast to coast, and manufacturers are developing products across all three variations that better respond to an array of personalized demands.


“In the coming year, contractors and technicians are going to see the need for more accurate and efficient ways to control indoor relative humidity (RH) year-round,” said Randy Lenz, product specialist for Aprilaire, a division of Research Products Corp. “As existing homes become tighter and more efficient, the need for humidification and dehumidification will become more apparent. Products that protect expensive home investments, such as wood flooring, kitchen cabinets, musical instruments, and art, are becoming more desirable.”

People deem the comfort and health of their families critically important, said Kevin Graebel, director of product marketing at Honeywell Intl. Inc.

A recent U.S. National Institute for Occupational Safety and Health (NIOSH) study showed that airborne transmission of the influenza virus is significantly reduced when the relative humidity in the space is above 40 percent. In the cold, dry winter months, this saturation level can often only be reached by using a whole-home steam humidifier.

“Humidifiers typically take about 72 hours for humidity levels to equalize in a home, and there can be a variance between floors up to 3 percent,” said Jay Ayers, IAQ product manager, Ingersoll Rand. “If there aren’t sustained heating run times, the consumer might not realize the full benefit of the evaporative type humidifier. The answer to achieving a desired humidity level in those climates is a steam type humidifier that operates independent of the heating system.”


Steam humidifiers offer great benefits to customers, and Ayers is excited that Trane will soon be active in this marketplace.

“We [Trane] are launching a steam humidifier,” he said. “It’s an electrode canister-type steam humidifier. These electrodes generate a positive-negative current between them, creating steam. You have a dispersion tube connected with a piece of hose going to the duct-
work, which can be located as far as 6-9 feet away from the humidifier. With a steam humidifier, I call that humidity on demand because, regardless of a call for heat or not, if there is a call for humidity, the steam humidifier will come on.”

According to Lenz, steam humidifiers are ideal for filling application gaps where evaporative products cannot be installed or do not offer enough capacity.

These gaps include a lack of duct or space on the duct to mount an evaporative humidifier, attic or crawlspace locations, in-floor heat, electric strip heat, boilers with radiators, heat pump systems, or where HVAC systems experience short run times (typically in milder climates).

In areas that are dry, a steam humidifier will deliver the right amount of humidification year-round.

“The modulating models within our electrode steam humidifier product line can deliver tighter control of humidity,” said Lenz. “Modulating humidifiers are being used in high-rise apartment renovations and in large homes where the homeowner is installing hardwood floors or wants to preserve delicate instruments and valuable art.”

While evaporative humidifiers are often less expensive to install, the most common complaint is that the home fails to reach the desired humidity level.

“In temperate climates, or during seasons when humidity levels are low but there is less need for heating, there just isn’t enough heat to evaporate the moisture off the pad,” said Graebel. “This is also true with many geothermal systems that have lower supply temperatures.”

Graebel also noted a steam humidifier can help add moisture to the air without an external source of heat, allowing the air handler to distribute humidified air to the home without an additional component. This can ensure the home is kept at the right humidity level no matter what is happening outside.


The differences between evaporative and steam humidifiers are readily apparent, as they utilize very different technologies.

“Evaporative humidifiers rely on the heat from the HVAC system flowing through the water panel to turn the water into a vapor, where steam humidifiers heat water to the boiling point to produce steam,” said Lenz. “Both technologies use the HVAC systems blower to distribute humid air through the ductwork to the home.”

Graebel highlighted Honeywell’s TrueEASE™ evaporative humidifier systems, which are flexible and designed to fit in more applications, he said. “An evaporative humidifier is typically the least expensive whole-home solution, both from an installation and a maintenance perspective,” said Graebel. “In a tight home that uses a warm-air furnace, an evaporative humidifier can often meet homeowner needs year-round.”

Trane offers a line of whole-home evaporative humidifiers. The line includes two sizes of bypass humidifiers and one power humidifier. Ayers said those humidifiers work best in heating markets with longer, colder winters. They require a fan to distribute air and are connected directly to the plenum at the furnace.


Ultrasonic humidifiers are most commonly used as portable, in-room units. These unique units can typically output more moisture than an in-room pad or wick-based evaporative humidifier and have a lower operating and purchasing cost than a warm-air humidifier, Graebel said.

“These types of humidifiers inject humidity as droplets instead of steam, so condensation could occur if the humidifier is placed too close to a surface,” said Graebel. “This is the primary reason these aren’t typically installed as in-duct systems, as water could easily condense on the ductwork. Additionally, if the water isn’t filtered first, the calcium and other dissolved particles in the water will settle out of the air as it evaporates.

“People will often notice more dust in rooms that have ultrasonic humidifiers because of this. As long as the user follows best practices for placing the humidifier and filtering the water, these are best used as in-room units.”

Publication date: 1/18/2016

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