In the last few years, mold has become a force to be reckoned with. Those responsible for designing new buildings and installing mechanical systems have become more cautious in their work.

Along with these fears have come myths about mold. One of those has to do with humidification. Can your whole-house humidifier cause mold to form within your home?

It’s actually very unlikely. So, how has this misconception come about? And what is the industry doing to dispel this rumor and promote the benefits of whole-house humidification?

Builder Fears

A humidification system can have numerous benefits for consumers. Introducing the correct amount of moisture into an environment can create profound changes within a home. Controlling humidity can help with indoor comfort. It can eliminate static electricity, and can help keep wood floors and furniture from warping.

Tim Kensok, director of indoor air quality products for Honeywell and chairman of the Humidifiers Section of the Air-Conditioning and Refrigeration Institute (ARI), explained that because mold can form through excess moisture within a building space, some individuals have started to question the use and safety of humidifiers.

“Mold has become a real litigious situation for builders and contractors,” said Kensok. “And when mold forms, the HVAC system gets blamed.” The homebuilder and general contractor come under fire as well. This has caused builders to be extra cautious when recommending certain mechanical systems. Since humidifiers produce moisture, some builders have stopped putting them into their plans, to avoid any possible blame or litigation if mold forms within the house.

Honeywell and the other manufacturers that make up the Humidifiers Section are working to educate builders on humidification and mold.

“The vast majority of mold problems are caused by bulk water entry or water that somehow leaks into the building envelope,” Kensok explained. “The connection between mold and moisture is starting to take hold in people’s minds. But humidification can help an environment, not hinder.”

Aprilaire, another member of the Humidifier Section of ARI, also reports that whole-house humidifiers are nothing to fear when it comes to mold.

“If you look at ASHRAE data, you will see that mold begins growing at humidity levels above 60 percent,” said Bruce Darkow, product manager for Aprilaire. “Aprilaire automatic humidifiers will only deliver up to about 45 percent, depending on the outdoor temperature and specific installation.”

Today’s whole-house humidifiers are designed to maintain optimal humidity levels.

Precise Control

Both Kensok and Darkow said that today’s whole-house humidification systems have the ability to make sure that the precise amount of moisture is introduced within the environment.

For example, Honeywell’s whole-house humidifier monitors outdoor temperatures, as well as humidity levels within the home. By constantly monitoring these two points and the fluctuation between them, the humidifier can control the level of humidity within the home while limiting unwanted side effects, such as condensation on windows.

This is also consistent with Aprilaire’s line of whole-house humidifiers.

“Aprilaire automatic humidifiers are designed to deliver the optimum amount of humidity under all conditions,” said Darkow.

According to Kensok, most humidifier manufacturers recommend an indoor relative humidity level of 35 to 50 percent rh. This can be achieved with a whole-house humidifier.

While manufacturers are educating builders about the need for humidification and clearing up mold myths associated with them, they are also educating HVAC contractors to be more proactive when offering systems to consumers. He explained that while some builders are not adding a humidification system to their plans because of mold fears, some HVAC contractors are not offering the systems because they are still unaware of the extra benefits it can bring their customers.

“I think there are still some contractors out there that think they just install heating and cooling systems,” Kensok said. “We are out there working with companies to change that.”

Part of what these manufacturers want contractors to know is that there is a market for add-on systems.

“Through our advertising and public relations efforts, we educate consumers and builders that whole-house humidifiers prevent other problems from happening with building materials such as cracking and splitting of wooden floors, woodwork, and doors,” said Darkow.

Kensok agrees with Darkow, and said that awareness is the key. Many homeowners do not know that there are products out there that will help create a more comfortable living environment.

“When humidification is offered to consumers, a very high percent will take it,” he said. “It comes down to awareness.”

The Right System

Honeywell is helping contractors realize that there are choices when choosing to install a system. These choices can help control humidity levels in the home and calm some worries that the system will introduce too much moisture.

But Kensok said that, in reality, one of the chief complaints with whole-house humidifiers is that they sometimes do not provide enough moisture to take care of low humidity levels.

One of the more popular solutions, according to Kensok, is to use a fan-powered, flow-through model. These models help control humidity because they are equipped with a built-in fan motor to generate airflow. The unit blows heated supply air across a humidifier pad to generate the moisture.

Kensok added that using a powered flow-through unit is especially ideal for multistage, variable-speed furnaces. He explained that these furnaces have reduced airflow during extended run times when only the first stage of heating is operating, which can limit the amount of moisture evaporated from the humidifier pad in bypass units. Also, these particular units do not require a bypass duct. This allows the unit to be installed in tighter, cramped areas.

The only downside, according to Kensok, is that the additional fan makes the powered, flow-through model cost a bit more than an unpowered, flow-through model, though this can be offset by reduced installation and material costs.

Kensok said another good choice is a steam-powered humidifier, which can provide consistent levels of humidity independent of furnace run time. The unit is mounted under a supply or return air duct, and has a heating element that boils water in the unit’s reservoir when the humidistat calls for more humidity. If the system does not call for heat, the steam unit can turn on the heating system fan to distribute the humidity.

Humidity products are evolving to provide further benefits. One example would be the Honeywell CleanSteam™ system, which uses a reverse-osmosis filter to eliminate chlorine and particulates in the water before it passes through a steam unit.

More humidifiers are also coming with improved control technology to provide optimum indoor humidity levels.

“For homeowners, it’s a question of keeping their furnishings and their home in good condition and living in a consistently comfortable environment,” Kensok said. “For contractors, it’s about recognizing the long-term value of such offerings for their customers.

“By creating additional customer pull for higher end, higher margin products, contractors not only offer customers additional comfort options, they create demand for annual maintenance and develop ongoing relationships with customers that can increase their bottom line over many heating seasons.”

Publication date: 08/11/2003