Humidifiers and Dehumidifiers

Buying Guide: Humidifiers, Dehumidifiers & Vaporizers at The Home Depot
Humidifiers and dehumidifiers are useful appliances that help maintain optimal humidity in your home. For most people, a relative humidity level between 40–50% in the summer and 30–50% in the winter is ideal. If the humidity drops below that level, the dry air can irritate your nose and throat, and dry out your skin, eyes and lips. Dry air may also shrink wood, damaging furniture, floors, and walls. Additionally, low humidity can make your home feel colder, especially in the winter. A humidifier counteracts these effects, adding moisture to the air to boost the humidity back to comfortable levels.
A dehumidifier extracts moisture from the air to reduce the humidity level. High humidity may spur mold and mildew growth, which can exacerbate allergies and rot your walls. High humidity can also make the air feel much warmer, especially during the summer. Substantial condensation inside your windows is a good indication humidity levels in your house are too high.
This buying guide explains the factors to consider when selecting a humidifier or dehumidifier so you can feel confident you’re selecting the right model for your needs.

Factors to Consider 


Humidifier Size – Tabletop, tower, console, whole-house
Humidifier Designs – Cool mist evaporative, warm mist, vaporizer, ultrasonic or cool mist impeller
Humidifier Ratings – Output per day, tank capacity, and run time


Dehumidifier Size – Portable or whole-house
Dehumidifier Ratings – Capacity and bucket size


Humidifier Size

Humidifiers come in four basic sizes:  
Tabletop Humidifiers Tabletop Humidifiers – Also called portable humidifiers, tabletop units are ideal for humidifying a single room. The typical design plugs directly into a wall and pulls water from a refillable tank. Tabletop units are lightweight, making it very simple to move them between rooms. Small tabletop units are sometimes called compact humidifiers.
Tower Humidifiers Tower Humidifiers – If you prefer to set a humidifier on the floor instead of a table, consider a tower design. These are perfect for humidifying a medium-size room. Some tower models need refilling less frequently than tabletop units.
Console Humidifiers Console Humidifiers – Like tabletop and tower humidifiers, console units are self-contained systems with refillable tanks, but they offer considerably more power. Console units are designed to humidify several rooms at a time, and they generally have larger tanks, which you don’t have to refill as often. Consoles are bigger and heavier than tabletop and tower models, but can still be moved between rooms.
Whole-House Humidifiers Whole-House Humidifiers – Also known as in-duct or online humidifiers, whole-house units introduce moisture directly into a forced air heating system. In the typical design, air blows through a wet wick, into a duct leading from the furnace. When the forced air system is running, it carries the moist air to every room in the house. Most whole-house humidifiers connect directly to the household water supply, which means you never need to refill them. They also have the lowest energy demands of the three humidifier sizes. Whole-house units require professional installation and will only work with a forced air heating system.

 Humidifier Designs

 There are four common humidifier designs, each with their own distinct benefits:
Cool Mist Evaporative Humidifiers – In this system, a fan blows dry air through a wick, which absorbs water from a refillable tank—or, in the case of a whole-house unit, the household water supply. Cool water from the wick evaporates into the air, boosting the humidity level. The wick also acts as a filter, removing any impurities in the water. Most whole-house units are evaporative humidifiers, and the design is common in tabletop and console models. Maintenance for console and tabletop evaporative humidifiers includes refilling the water tank 1-2 times a day, depending on usage, and replacing the wick every two months or so. With a PermaFilter evaporative humidifier, you can clean the wick instead of replacing it regularly. Evaporative models have relatively low power demands.   Cool Mist Evaporative Humidifiers
Warm Mist Humidifiers – Also known as steam humidifiers, these models work like a tea kettle. A heating element boils water from a refillable tank or the household water supply, generating steam that humidifies the surrounding air. Like evaporative humidifiers, warm mist humidifiers remove impurities from the water, producing clean saturated air. One key benefit of this design, especially during the winter, is the steam helps keep rooms warm. Since they don’t include a fan, warm mist humidifiers are very quiet. Tabletop and console models require you to refill the water tank periodically, but there’s no wick to replace. However, it may be necessary to clean the unit regularly, as impurities from the water can build up in the tank.    Warm Mist Humidifiers
Vaporizers – Small, low-output warm mist humidifiers are called vaporizers. These units have a built-in water reservoir, rather than a removable tank. Vaporizers
Ultrasonic Humidifiers – In this system used in many tabletop models, a metal diaphragm vibrates at ultrasonic frequencies to break water up into a cloud of tiny droplets. Ultrasonic humidifiers are the quietest of the available systems, and have relatively low power demands. They do not remove all water impurities, but some include “demineralization cartridges” that filter out much of this material. It’s necessary to refill the tank regularly, but there is no filter to replace. Ultrasonic humidifiers generally produce a cool mist, but some models include a heating option that helps keep the room from getting too cold. Ultrasonic Humidifiers
Cool Mist Impeller – In this tabletop design, a spinning disc generates a fine mist of cool water. Like ultrasonic humidifiers, impeller models are quiet and don’t use much power. They do need to be refilled, but there aren’t any filters to replace. Since impeller models don’t remove water impurities, it’s best to fill them with distilled water and clean the tanks regularly. Cool Mist Impeller

Humidifier Ratings

When comparing humidifier models, consider these common power and performance ratings:   

Output per Day – The maximum amount of water the humidifier will add to the air per 24 hour period. Output
  is the standard measure of a humidifier’s power, which determines how many rooms it can humidify. Some
  models may include a square footage or room number recommendation on the label as well. Refer to the
  chart below for general output ranges and corresponding applications.

Humidifier Ratings

Tank Capacity – The amount of water the refillable tank can hold, listed in gallons. Typically, you need to
  refill larger tanks less frequently than smaller tanks.

Run Time – How long the humidifier can run on a full tank of water.  


Humidifier Features 

 • Adjustable Humidistat – A standard control system that automatically shuts the humidifier on and off to 
   maintain a preset humidity level
• Digital Display – A display of current relative humidity levels and settings
Timer – Programmable control that lets you set the humidifier to run at certain times of day
Automatic Shut-Off – A standard feature that shuts off the humidifier when the tank is empty
Medicine Cup – A feature on steam humidifiers that evaporates vapor medication
Filter sensor – A system that alerts you when it’s time to replace the filter
Dishwasher-Safe Tank – A tank designed for easy cleaning in the dishwasher
Safety Listing - A guarantee that an independent testing agency, such as Underwriters Laboratories (UL mark),
  Intertek (ETL mark) or the Canadian Standards Association (CSA mark) has ensured the humidifier is safe for its
  rated use
ENERGY STAR ® – A label indicating the product meets stringent energy efficiency guidelines outlined by the
  U.S. Department of Energy and the Environmental Protection Agency


Dehumidifier Size

Portable Dehumidifiers Portable Dehumidifiers – These models work the same basic way as a window air conditioning unit. A fan blows moist air from the room across cold refrigerant-filled coils, which cool the air, causing the moisture to condense into water droplets. In a typical design, the water collects in a bucket, which you need to empty periodically. Many models also have a hose attachment, which lets you drain the water directly into a sink or basement drain. Unlike an air conditioner, a dehumidifier includes a separate heating coil that warms the air again before expelling it into the room.
Whole House Dehumidifiers Whole House Dehumidifiers – These units work the same basic way as portable models, but have the extra power necessary to dehumidify several rooms at once. Typically, a whole-house unit can service about 3,000 square feet of living space. Some models connect to the ductwork in a central air or heating system, while others are self-contained systems. Some models can operate in either mode. Whole-house units empty collected water into a drain leading outside the house, rather than a refillable bucket. Models that connect to central heating and air system usually require professional installation.

Dehumidifier Ratings

When comparing dehumidifier models, consider these common ratings:

Capacity – The volume of water the unit can remove over a set period of time, generally represented as
  pints per day. Capacity is the standard rating for dehumidifier power, which indicates the moisture level
  and room size the unit can handle. Refer to the chart below to match dehumidifier category and capacity
  to suggested applications.

Dehumidifier Ratings

 • Bucket size – The size of the water collection bucket. A dehumidifier with a larger bucket can run for
   a longer period of time before you need to empty it.

Dehumidifier Features

Adjustable Humidistat – A system that turns the dehumidifier on and off automatically to maintain a preset
  humidity level
• Digital Display – A display of current relative humidity levels and settings
Automatic Shut-Off – A standard feature that shuts off the dehumidifier when the tank is full
Drain Hose Connection – A connection that allows you to bypass the bucket in a portable dehumidifier and
  empty water into a hose leading to a drain
Automatic Defrost – A system that saves energy by automatically shutting off the unit if frost forms on the
  coils, preventing proper operation
Multi-Speed Fan – A type of fan that runs at slower speeds in less humid conditions, reducing noise and
  energy consumption
Wheels or casters – A standard feature that makes it easier to move portable dehumidifiers from room to room
• Built-in Pump – A system that allows you to run the drain hose up to a window, sink or elevated drain
Safety Listing: A guarantee that an independent testing agency, such as Underwriters Laboratories (UL mark),
  Intertek (ETL mark) or the Canadian Standards Association (CSA mark) has ensured the humidifier is safe for its
  rated use
ENERGY STAR ® – A label indicating the product meets stringent energy efficiency guidelines outlined by the
  U.S. Department of Energy and the Environmental Protection Agency