Avoiding humidity problems can be beneficial for more reasons than comfort. Health, for example, is a primary concern when questioning the need for a humidification or dehumidification system. Is the air too dry? Are there nosebleed and scratchy throat complaints? Is the air too wet? Has the mold growing in the shower expanded its territory to the windowsill in the room down the hall? Mold remediation is another prime reason for considering a humidity control application. Bob Sycks, director of sales for central and commercial products at Heat Controller, took a moment to explain the science behind the humidity and mold connection and its affects on the average home.


“Most people are surprised to learn that the air in their homes is likely to be more polluted than outside air,” said Sycks. “What they don’t stop to consider is that we spend a significant amount of our time indoors and today’s homes are tighter than ever before.”

Sycks went on to warn that efforts to conserve energy could be adversely affecting the indoor environment. Insulation, storm doors, triple-pane windows, weather stripping, vapor barriers, and similar measures have the potential to trap contaminated air inside the home. In light of this, some scientists are now cautioning that indoor air can be four or five times more polluted than outside air.

“Health-wise, we’re seeing the effects in the increasing numbers of individuals suffering from allergies and asthma,” said Sycks.

According to Sycks, the most common household biological contaminants that he commonly hears about are mold, mildew, and dust mites. These elements all have one thing in common - they require moisture and nutrients to survive.

“Mold spores are present both outside and inside, but they generally don’t cause problems unless there’s a wet or damp surface for them to grow,” pointed out Sycks. “Once established, spores can float through the air and form new colonies. Some molds produce allergens that cause symptoms such as itchy eyes, sneezing, and skin irritation. Other molds can cause asthma attacks; certain types produce mycotoxins that are potentially harmful if touched or inhaled.”

Dust mites exist in every home as well. These microscopic insects live in mattresses, pillows, carpets, upholstered furniture, clothing, and other items made from fabrics. They feed on skin flakes from humans, surviving and multiplying in the presence of moisture. Dust mites can trigger symptoms similar to hay fever in people with dust allergies and asthma attacks in asthmatics.


“A major key to a healthy house is control of excess moisture,” said Sycks. “Controlling the amount of moisture in the home is the first step in controlling these harmful indoor pollutants.”

When contractors think of damp areas, they commonly consider basements to be the most likely candidates for mold. Kitchens and bathrooms, however, can also harbor mold and mildew, as can closets and storage areas without ventilation. Contractors should check any place there’s condensation.

“To counter indoor air pollution resulting from excess moisture, most experts recommend keeping humidity in the home at 50 percent or less,” noted Sycks. “The best way to do this is with a whole-house dehumidifier. These units keep the entire structure at the desired humidity level, not just the basement or a single room as with a portable dehumidifier.”

To keep the humidity level under control, Sycks suggests Comfort-Aire’s WHD-130A. This unit is connected in-line to the central a/c system ductwork. A sensor determines if dehumidification is needed and the unit’s fan runs on a periodic basis to sample the total humidity level in the home. If it senses a humidity level higher than desired, it will turn on the compressor and run until the desired level is reached.

“Interestingly, a whole-house dehumidifier can also save energy, even though it’s another piece of HVAC equipment,” said Sycks. “With one installed, the central air conditioner may actually run less.”

This is because humidity is a critical factor in comfort, affecting the body’s natural ability to regulate temperature.

“Drier air is more comfortable, so many people raise the temperature setting, reducing the load on the a/c and helping extend its life,” noted Sycks. “On the other hand, if the a/c can’t keep up with warm, moist conditions or if the home is so energy efficient that the a/c doesn’t have to run as often to maintain the temperature, the humidity level can creep upward.”

When this occurs, homeowners will often lower the thermostat setting to feel more comfortable, but instead they create a cold and clammy atmosphere. This occurs because cold air holds less moisture than warm air, so the relative humidity (rh) can actually increase although the air conditioner is running.

By sensing the rh inside the home, a whole house dehumidifier keeps the humidity at the desired level so it dehumidifies without overcooling. With a dehumidifier, the greater the unit’s capacity, the faster the home can be brought to a comfortable humidity level, said the company. Comfort-Aire’s WHD-130A, for instance, has a 130-pint per day capacity.

“Dehumidification can no longer be considered just an off-shoot of air conditioning,” said Sycks. “As we continue to remodel and build homes that are more energy efficient, controlling humidity will become increasingly important, not just to prevent damage to the home and furnishings, but to avoid potential health problems.”

Publication date:08/11/2008