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Humidifier Buying Guide

Everything you need to find the best humidifier for the office, bedroom, kids room, or any space too dry for comfort.

Yvonne Harbison
Yvonne Harbison
Toddler walking into room with humidifier turned on

The human body relies on air and humidity to help maintain a consistent internal temperature by evaporating heat moisture. Air can hold a lot of water, which can influence how a person feels if the humidity level in the air adds to the heat moisture rather than wick it away. When the temperature drops far enough below the humidity level that everything starts drying out, the dry cold can wring out too much moisture. 

During winter in some areas, humidity levels can drop to as low as 10% or less. Those are the days where you catch a chill, or maybe can’t quite get warm, because people tend to prefer a relative humidity level above 30%.

Running heaters and air conditioners to keep a consistent room temperature can be especially draining on the humidity levels. Low humidity can cause dry skin, dry eyes, and irritate the sinuses, inviting trouble like illnesses or headaches. When you’re tired of the natural, seasonal ups and downs of humidity, a good humidifier can help fight back.

What Is a Humidifier?

A humidifier is used to adjust the humidity level indoors to keep it comfortable and healthy. There are different types of humidifiers, but the basic operation of a humidifier is to turn water into a mist or steam and introduce moisture back into the air.

When to Use a Humidifier

It can be useful to introduce a humidifier in rooms that are regularly at humidity levels between 30 and 50 percent. Below 30 percent humidity, the air can draw moisture out of wood furniture or flooring, resulting in damage, like warping or cracks. Wallpaper can begin to peel away as the moisture is pulled out and weakens the adhesive. 

As things dry out, there’s an increase in static electricity, so people start to notice when simply walking across carpet can be a shocking experience. Humidifiers even keep houseplants greener and healthier because lowered humidity is drawing moisture from the soil. It can help when someone is already sick, as moisture in the air can ease congestion when battling coughs and colds.

Woman blowing her nose
Humidifiers offer relief from seasonal ailments, from allergies to colds.

Common health problems often associated with dry air include:

  • Dry airways that irritate asthma, coughs, and sore throats
  • Dry skin, cracked lips
  • Sinus inflammation and pain
  • Headaches
  • Allergies

Often, if there’s an increase in any of the symptoms above, the first preventative step you can take is to bring out the humidifier.

How a Humidifier Works

There are two main ways humidifiers introduce moisture back into the air: Warm mist created using steam, and cool mist, created through movement and evaporation.

Humidifier releasing steam
Hot water from warm mist humidifiers cools quickly to room temperature as mist.

Warm Mist

Warm mist humidifiers boil water in the tank and then filter the steam out as a mist to add to the humidity. 

  • They can operate more quietly than other humidifiers because the water turns into steam and doesn’t require a fan to blow the moisture into the room.
  • The base of the humidifier gets very hot and produces scalding water, but unless you are sitting directly in front of the filter, the air has returned to room temperature by the time you can breathe it in. 
  • Because the tank boils the water before it evaporates, warm mist humidifiers can use regular tap water rather than filtered or bottled water. Boiling the water reduces the problem of mineralization and hard water scaling inside the tank. 
  • While the mist evaporates to a cooler temperature, the water inside the tank and the humidifier itself are still an extra heat source, so warm mist humidifiers have the bonus of slightly warming the room around it. 

Similar to the warm mist humidifier is the vaporizer. Vaporizers are often smaller and less powerful than steam humidifiers. They are designed for personal use, as their primary goal is to provide medical benefits. With vaporizers, medications or aromatherapy additives applied to a tray inside the humidifier turn into vapor with the steam. 

Use warm mist humidifiers with caution, as boiling water can damage people, pets, and furniture if not carefully handled. Because of the scalding water, they are not advised for use around small children.

Cool Mist

Cool mist humidifiers are seen as the safer alternative because the mist is achieved by the movement of air and evaporation, without the hot air required for steam.

There are three common ways used to create cool mist:

  • Evaporative humidifiers: A wick or filter absorbs water from the tank, and a fan pulls in air from the room to push through the filter. The moisture evaporates and is pushed back into the room.
  • Ultrasonic humidifiers: A nebulizer vibrates under a tank of water, with the movement agitating the water enough to create the mist.
  • Impeller or Air Washer humidifiers: A spinning disk moves water through a diffusion screen, creating a mist and removing impurities and allergens from the air.

The air pulled into the humidifiers is cooled by the water in the tank, and potentially cooling the air in the room. 

When it comes to noise, ultrasonic humidifiers are the quietest of the cool mist humidifiers. Both evaporative and air washer humidifiers rely on fans or spinning disks that create extra noise.

Humidifier Features to Look For

Look for a humidifier that has a design and color style that is complementary to your home, but also one that is functional. There are a variety of different brands to choose from, and each one will offer different features to better match the needs of your home.

Ease of Maintenance

It’s very important to find a humidifier that is easy to take care of. They will have to be cleaned regularly, which will involve safely removing and then reassembling the tank and other parts.

  • Look for easy to understand operational buttons, like power, mode, or speed.
  • Look for sturdy construction and pieces that fit together smoothly. 
  • Look for an insulated base that will not damage the furniture it is placed on due to moisture or heat.

Ease of Use

There are a variety of features available with different humidifiers. The key is to know what’s available before you make your purchase, so you’re sure to end up with a machine capable of performing exactly the tasks your family needs.

Vornado 20 Inch Wide 4 Gallon Vortex Humidifier
Humidifiers offer many features that make them easy to use in any room.

Included Humidistat. The Humidistat turns off the humidifier when the tank runs out of water, or when the air saturation hits the appropriate humidity level

Multiple speeds/output. Adjustable outputs allow you to adjust the amount of moisture and time it takes to add the right amount of humidity to the air by changing the speed of the air flow.

Indicator lights. Especially important with heat-generating humidifiers, it’s useful to find a machine that very clearly indicates when the machine is powered on.

Digital displays. Look for digital displays that present clear and useful information about the power status, the humidifier mode, and the fan settings.

Timer with automatic shut-off. If there’s no humidistat included with the unit, go with the timer to help make it easier to monitor the water levels in the tank.

Replaceable filters. Filters can be an added cost of humidifier operation. Make sure the filters are easily accessible and replaceable. 

Combination of warm and cool mist humidifiers. Some humidifiers allow you to choose between warm and cool mist modes.

Humidifier Types

There are humidifiers meant for every type of room, from the small home to the busy office building. The larger the humidifier, the better coverage it can provide.

Whole-house humidifiers are usually evaporative humidifiers. They are an extra filter that works in addition to your HVAC system to cover the largest possible area, often using the building’s interior ventilation systems. Because it is an evaporative system, the water tank on whole house humidifiers is connected to the water line and automatically monitored, with no tank refills needed. For whole-house humidifiers, look to bypass humidifiers, drum humidifiers, or in-duct or furnace humidifiers.

Console humidifiers are larger appliances that can provide humidity to multiple rooms, but are still small enough to be a more portable unit. The water tanks require manual refills, so make sure you choose a model that has a tank size that will fit under a sink faucet.

Tabletop humidifiers are single room humidifiers, small and easily portable. They are useful in small rooms, or for adding a little humidity to specific parts of rooms. They also have a manually refillable tank, but it’s best to use distilled water for tabletop humidifiers, as hard water from the tap can interfere with it’s safe operation.

The Right Humidifier by Room size

The size of the room is a good way to determine the moisture output needed from a humidifier. Determine the square footage of the area that needs some adjusting, whether it’s an entire room, an entire building, or just your own personal office area.

  • Travel Humidifiers cover small spaces, up to 25 square feet. 
  • Small Room Humidifiers cover between 25 and 299 square feet. 
  • Medium Room Humidifiers cover 300 to 499 square feet. 
  • Large Room Humidifiers cover 500 to 999 square feet. 
  • Whole House Console Humidifiers cover areas of 1,000 square feet or more.

Humidity Warnings and Precautions

Dirty humidifiers can make people sick. Too much moisture in the air will not provide any health benefits and is potentially harmful. Bacteria, mold, mildew, and other dangerous microbes grow best in wet, humid places. Humidifier water tanks create breeding grounds for these microbes when the machines are not properly cared for. It’s also important to keep an indoor humidity level at or below 50% to avoid excess moisture buildup on windows or walls that could become grimey or moldy in unnoticed crevices. 

A good approach to humidity control is to use a hygrometer and monitor the room when using a humidifier. A hygrometer is a digital device that measures moisture and humidity in the air and the room temperature. Look for a hygrometer to help keep the humidity level in your home in the ideal range between 30% and 50%.

How to Clean Your Humidifier

To keep your home and air healthy, it’s important to clean the humidifier regularly. The humidifier should be cleaned before and after every use, to keep the water tank dry and clean. 

Weekly or multiple times a month, depending on how often you use the humidifier, descale, clean, and dry all parts of the humidifier.

If you won’t be using your humidifier for a long period of time, clean the humidifier thoroughly before putting it into storage, and then again before you use it afterward.

Humidifier Cleaning Tips

  • Take apart the humidifier and use 1 cup of white vinegar and a toothbrush to scrub down all accessible areas of the machine parts.
  • Pour 1 tablespoon of bleach in the tank and add 1 complete tank of water. Shake the tank to be sure the sides of the tank are descaled and covered. Let the water and bleach mix rest in the tank for 20 minutes. Rinse the tank out completely, repeatedly, until the smell is gone.

Humidifiers and Essential Oils

A common question is whether or not you can use essential oils in a humidifier to introduce the oils into the air you breathe. The simple answer is that, no, it’s not as clever an idea as it might seem on the surface. Some humidifiers are compatible with some oils, but those brands and products will be labeled.

Essentail oil bottle and an essential oil diffuser
Essential oils are only effective with specifically designed humidifiers.

Some important points about essential oils and humidifiers:

  • Essential oils will not diffuse as well in a humidifier because humidifiers are not designed to break down the water and oils together, which can leave larger droplets of oil escaping and making a mess or damaging furniture.
  • Certain oils can deteriorate the plastic parts of a humidifier. It’s particularly important to avoid citrus-based oils (such as lemon, lime, or grapefruit.)
  • Warm mist humidifiers will be too hot for the essential oil to survive. The boiling water will purify the oils and it won’t have much of an aroma left.
  • Essential oils can be used with some ultrasonic humidifiers, with care. They are very similar in design to the smaller essential oil diffusers, however, a diffuser is specifically designed to provide the best delivery of the essential oils.

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