How Dehumidifiers Work

Do you need a dehumidifier?

Start by taking a look around your home. The most noticeable symptoms of excessive humidity may include wet stains on your walls and ceilings, rotting and weakened wood, mold and fungus, condensation on your windows, peeling wallpaper, blistering paint, and a generally musty, stuffy feeling.

In addition to those somewhat obvious signs of humidity, there are also some more subtle conditions you can watch out for. For example, you may want to look into a purchasing a dehumidifier if your doors, cabinets or windows are sticking, or if your floors are especially creaky. When wood absorbs moisture, it swells. This pushes apart joints, loosens screws and nails, and generally compromises your home's strength. While your noisy stairs might be a simple nuisance now, if humidity is the underlying issue, your problems could get worse.

Dehumidifiers can also help mitigate the effects of common allergies to dust mites, fungus and mold; if the air in your home is excessively moist, it can encourage the growth of these allergens.

Even if you don't have allergies, preventing mold growth is a good reason to consider getting a dehumidifier. Mold only requires a bit of moisture to grow, and it can set up shop in your home as soon as one of its airborne spores finds a hospitably damp surface. A mold problem in your home can cause serious illness. And once it shows up, mold is a pain to eradicate and can permanently stain or damage whatever it's decided to live on. The easiest strategy is to just keep it from showing up at all.

You can also use a dehumidifier to discourage insects from moving in with you. Roaches, silverfish, spiders and centipedes all love a moist environment. Keeping the air in your home relatively dry will drive away those unwanted tenants. Additionally, if you've got a cold or a particularly bad, congested cough, using a dehumidifier may free up your breathing and help you sleep better at night.

As you can see, there are plenty of good reasons why you might consider using a dehumidifier. To find out more about these devices and related topics, follow the links below.

Related HowStuffWorks Articles


  • Achoo Allergy and Air Products. "Dehumidifiers" (November 12, 2009)
  • Brain, Marshall and Charles W. Bryant. "How Air Conditioners Work" (November 1, 2009)
  • Consumer Reports. "Dehumidifiers." June, 2008. (November 1, 2009)
  • Dehumidifier Experts. "Relative Humidity and Whole-House Dehumidifiers." May 2, 2008. (November 8, 2009)
  • Dehumidifier Experts. "How Dehumidifiers Work." May 6, 2008. (November 8, 2009)
  • Dehumidifier Experts. "The Dangers of High Humidity in Your Home." May 6, 2008. (November 8, 2009)
  • Energy Star. "Dehumidifiers: ENERGY STAR" (November 10, 2009)
  • Environmental Protection Agency, Office of Air and Radiation, Indoor Environments Division. "A Brief Guide to Mold, Moisture, and Your Home" September 18, 2008 (November 1, 2009)
  • Laumer, John. "Can I Water My Plants With It?" July 29, 2005. (November 8, 2009)
  • Nebraska Public Power District "Operating Costs of Household Appliances"