Humidifiers are invaluable solutions for helping to relieve the adverse effects of dry wintry air, alleviate symptoms of the common cold and certain respiratory illnesses, protect valuable belongings, and boost your overall comfort indoors throughout the year. Just as a dehumidifier reduces the amount of moisture in excessively humid air, a humidifier works in the opposite way by adding moisture to excessively dry air. Using a humidifier regularly helps you create a healthier and more comfortable space during the colder months or year-round.
When shopping for a humidifier, it's helpful to understand how these appliances work, how to choose from the range of types, and what to expect during operation and maintenance. To get information on these topics and more, we have devised this list of our most frequently asked questions about humidifiers.
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Q: Why do I need a humidifier?
A: Humidifiers help make dry air more comfortable by boosting your indoor humidity level. Typically, your humidity level - or the amount of water vapor in the air - drops during the colder months because cold air cannot hold as much moisture as warm air. Even when we crank up our thermostats or use space heaters to heat the air, moisture content does not get replaced. The air can soon feel even drier, spawning uncomfortable health symptoms such as:
Sore, scratchy throat
Dry sinus passages
Dry, scaly skin
Aggravated respiratory conditions
Overtime, dry air can also undermine your home's infrastructure and interior, causing wood floors and furniture to warp or separate, paint and wallpaper to peel, and uncomfortable static electricity to develop. Additionally, air with too little humidity may cause irreversible damage to valuable belongings such as musical instruments and fine art. A humidifier can help combat these issues and prevent them from returning.
You might also use a humidifier to help relieve and treat an ongoing sinus or respiratory condition, help your baby or young child breathe easier when they are congested, or enjoy comfortable humidity year-round if you live in a dry climate.
Q: How does a humidifier work?
A: No matter the type of technology they use, all humidifiers essentially function in the same manner. These appliances force moisture into your indoor air in the form of an invisible mist. Different types of humidifiers may have different ways of doing this. An evaporative humidifier, for example, uses an internal fan to pull air into the unit and pass it across a water-saturated wick filter to absorb moisture. After air has been saturated with moisture, the fan then propels it out into your space to circulate.
Ultrasonic humidifiers use an ultrasonic vibrating diaphragm instead of a fan to create micro-fine water droplets that are forced into your air. Also lacking a fan, warm mist humidifiers heat the water to boiling until it vaporizes. Then, heat energy helps move moisturized air throughout your space. In-duct humidifiers work in a similar fashion, using your forced air furnace to humidify the air at the same time you heat your space.
Q: What is the ideal humidity level I should maintain?
A: A healthy humidity level is one that measures between 30% and 50%. Humidity that measures above 50% creates a breeding ground for mold, dust mites, bacteria, and other pests. Humidity that measures below 30% increases the likelihood that cold and flu viruses will spread while also leading to uncomfortable respiratory symptoms. Too-dry air can also cause damage to your home's foundation and certain furnishings. To avoid the problems of too little or too high humidity, we recommend you maintain a humidity level of between 45% and 50%.
To ensure that you're reaching an optimal humidity level, invest in an inexpensive hygrometer, which measures the humidity level of the air. With this information, you'll know if you need to adjust humidifier operation accordingly. As an alternative, look for a humidifier that has an internal hygrometer that continuously measures your humidity and adjusts humidifier output automatically.
For more information on relative humidity and your health, read our article Understanding Relative Humidity.
Q: Cool mist or warm mist—which type of humidifier should I choose?
A: The type of humidifier you choose primarily depends on your preference for the kind of moisture you'd like to add to your space. Cool mist humidifiers distribute room-temperature moisture into your room. Although the moisture distributed is not exactly cold moisture, the cool mist can make your room's temperature fall a few degrees. Warm mist humidifiers, on the other hand, distribute heated moisture into your space, which can make your temperature rise a few degrees.
To help with your choice, consider that cool mist humidifiers are popular for year-round use when temperatures fluctuate. Warm mist humidifiers are helpful when you want to maintain a warm indoor temperature in the wintertime. If you have trouble deciding on an option, look for a humidifier that offers both capabilities. For example, the Air-O-Swiss 7144 Digital Ultrasonic Cool and Warm Mist Humidifier allows you to select cool or warm mist operation to suit your preference.
For more information on the differences between these two options, read our article Cool Mist Vs. Warm Mist Humidifiers.
Q: What is an air washer and how does it compare to an air purifier?
A: Air washers are a relatively new type of humidifier that helps clean your air while you humidify. Using impeller technology or an added air filter, air washer humidifiers filter out large particles and allergens before releasing humidified air into your space. Air washers, such as the Air-O-Swiss 2055A Air Washer Humidifier, differ from air purifiers in that they remove only larger particles often measuring at least 1.5 microns in size. Air purifiers - particularly HEPA air purifiers - are capable of removing microscopic allergens and particles measuring as small as 0.3 microns in size. These types of particles are typically the ones that aggravate moderate to severe allergy conditions.
If you suffer from mild allergies, an air washer provides some benefit in eliminating airborne irritants. However, if you have moderate to severe allergies, we recommend using an air purifier to relieve your symptoms.
Q: What size humidifier do I need?
A: Sizing a humidifier depends mainly on the square footage of the area you want to humidify. Most humidifier manufacturers provide a square foot coverage range as part of their product's specifications. Before shopping, measure the approximate area of your room or the space you want to humidify. Armed with this information, look for a humidifier that is designed to cover an area similar to the size of your space.
Keep in mind that compact tabletop humidifiers will typically be enough to humidify single rooms and smaller spaces. Large tabletop and mini-console humidifiers will humidify medium- to large-sized areas. Console and in-duct whole house humidifiers will cover large areas and, sometimes, your entire house.
Q: What is humidifier capacity?
A: Humidifier capacity refers to the maximum moisture output a humidifier produces per 24 hours. Capacity differs from a humidifier's water tank size, which refers to how much water the reservoir can hold when it's filled completely. Water tank size is typically less than a unit's capacity. Tabletop humidifiers are usually available in 1- to 4-gallon capacities. Console humidifiers, such as Essick Air humidifiers, feature higher capacities and can often run for longer periods of time.
Q: How do I add water to the humidifier?
A: Portable tabletop and console humidifiers feature one or more water reservoirs. To fill your humidifier, simply open the water reservoir and pour in clean water. Some humidifiers will be small enough to carry to a sink for filling while others may feature top-fill reservoirs that make it easy to fill with a pitcher or hose. Furnace humidifiers, such as the Honeywell HE120 Whole House Drum Humidifier, do not have water reservoirs. Instead, these humidifiers hook directly to your home's water supply to draw water as needed.
Q: How often will I need to refill my humidifier?
A: Most portable humidifiers will need to be refilled once every 24 hours if you plan to use it continuously throughout the day and night. Select models, such as the Pure Guardian 72-Hour Ultrasonic Humidifier and some large console humidifiers, provide continuous humidification for more than 24 hours per refill. If you use your humidifier intermittently, you'll need to refill it less often.
Q: Can I use hard water to fill my humidifier?
A: Yes. However, if you plan to use hard water to fill your humidifier, be sure to choose a humidifier that includes a mineral cartridge. Hard water contains elevated mineral content that, when released into your air, may solidify as an unhealthy irritant known as white dust. Breathing in white dust over prolonged periods of time may aggravate existing respiratory issues or cause new issues to develop. Mineral cartridges absorb most of the mineral content from hard water so there is less of a risk of it being released into your air. If your humidifier does not have a mineral cartridge, we recommend filling your humidifier with distilled water, which is free of minerals.
Q: Can I set my humidifier on a timer?
A: Yes. Many newer humidifiers include advanced digital controls with programmable timers. Timers allow you to program operation to begin at a certain time and shut off at a certain time in order to save energy and ensure that the unit runs only when needed. Some humidifiers may include a countdown timer instead of a full programmable timer. Countdown timers allow you to program a shutoff time if the humidifier is already running.
Q: How much energy does a humidifier use?
A: It's difficult to say how much of an impact a humidifier will have on your monthly energy bill. The answer to this depends on many factors including the number of hours you use the humidifier each day, your humidification speed setting, the type of your humidifier you're using, and your electricity rate. To help you better estimate energy usage and weigh potential energy costs, keep these rules of thumb in mind.
Cool mist humidifiers generally humidify larger areas while using less electricity than warm mist humidifiers.
Warm mist humidifiers use slightly more electricity than cool mist humidifiers because they heat water before releasing it as a warm invisible mist.
Console humidifiers will use more power throughout the day to humidify than compact tabletop models.
In-duct humidifiers are the least expensive to run and most energy-efficient humidifiers to use in the long-run.
Q: How loud is a humidifier?
A: It depends. Evaporative humidifiers, which use internal fans to generate airflow, will typically be the loudest options because they have more moving parts. These humidifiers create a white noise that may be considered loud at first, but eventually fades as background noise. Warm mist humidifiers are less noisy than cool mist models because they don't use a fan. Ultrasonic humidifiers are the quietest humidifiers available because they produce ultrasonic sound waves at a frequency higher than we can hear.
Q: How do I clean my humidifier?
A: It's important to clean your humidifier on a regular basis to ensure that it produces clean, healthy moisture. Without regular cleaning, your humidifier can quickly become a breeding ground for allergens and bacteria that can ultimately be released into your air. We recommend you clean your humidifier's water tank thoroughly every few days using a soft-bristled brush and a mild cleanser. Rinse it thoroughly and wait for all components to dry before refilling with fresh water and turning on. In addition, wipe down the exterior with a damp cloth. For more information, read our blog post on How To Clean A Humidifier.
Be sure to consult your humidifier owner's manual for additional maintenance steps and tips specific to your model.
Still Have Questions?
To learn more about our humidifier models and for help choosing the best humidifier for your needs, visit our humidifiers section and Learning Center. Not sure what's best for you? We can take the guesswork out of decision-making. Contact our air treatment experts toll-free at (800) 934-9194 for a free consultation and product recommendation. We want to help make your indoor environment a healthy one.