Indoor air that lacks the right amount of moisture can dry out your skin, irritate your respiratory system and damage wood floors and furniture. Humidifiers keep the relative humidity (RH) in your home at comfortable and healthful levels of about 30% to 50% year-round. While some humidifiers control humidity levels in one room only, a whole house humidifier covers your entire home. In this article, we’ll discuss how various types of whole home humidifiers work and provide best-practice maintenance and installation tips. We’ll also name our eight top picks for best whole house humidifiers and explain why we chose them.
How whole house humidifiers work
Whole house humidifiers range from simple portable plug-in units you can pick up at the mall to more elaborate and feature-rich central units. The products use a variety of different technologies, but there are three types of systems in common use today: evaporative pad humidifiers, steam humidifiers and evaporative cool mist humidifiers.
Steam and evaporative pad systems are both central units, capable of humidifying a whole house. Most can cover up to about 4,000 square feet, although some can handle more than 6,200 square feet. On the other hand, cool mist evaporative humidifiers are portable humidifiers. Although some cool mist evaporative units can provide moisture throughout an entire small home, or even a medium-sized home up to about 3,600 square feet, most portable units are limited to use in a single room.
All types of humidifiers are operated through a humidistat. The humidistat turns the humidifer on and off as needed to reach the desired moisture level.
Evaporative pad humidifiers. The evaporative pad humidifier is a central unit that uses your existing HVAC air ducts and is sold as an installation kit. You can DIY or hire a professional for installation. These humidifiers work by blowing warm air over an evaporative pad, also known as a water panel. When water trickles down the pad, the warm water evaporates and the moisture is absorbed into the air.
The pad humidifier, in turn, is available in two types. One, the fan-powered or “power” humidifier, mounts to the side of the supply ductwork. Its built-in fan pulls air in across the pad. After the air is humidified, it is then blown back into the ductwork. These units are relatively noisy, though, and they consume more electricity because of the fan.
The second type of pad humidifer, known as a bypass humidifer, comes with a bypass duct. The bypass humidifer uses the fan on the furnace to recirculate some of the warm supply air across the pad and then back into the return ductwork. When installing a bypass humidifier, make sure the existing ductwork is sized properly to give your furnace the right amount of airflow.
A drum humidifier is a variation on the evaporative pad humidifier. In the drum humidifer, a rotating pad spins around in a pan of water inside the unit, releasing moisture into the warm air stream.
Hiring a pro to install a non-steam central humidifier such as a pad system typically costs between $100 and $300, depending on your heating system configuration and local rates. If you aren’t much of a DIYer, the money might be worth it.
Steam humidifiers. Steam humidifiers can offer even more precise humidity control than evaporative pad humidifiers, but they’re also more expensive and challenging to install. Steam humidifiers are sold as installation kits, too. Traditionally, they use electric probes to boil water and inject the steam into the air. Some models rely on existing air ducts, whereas others have their own fans.
Installation often requires a dedicated electrical circuit of a manufacturer-specified voltage, plus an electrical outlet where the humidifier is located. The humidifier must then be synced together with the electrical system and any required ductwork. Some units need only an annual cylinder replacement, but others must get a thorough cleaning once a year to scrape away any mineral deposit buildup.
Technicians generally charge anywhere from $600 to $1,600 to install a steam humidifier, again depending on configuration and local rates. For that reason, most steam humidifiers are commercial systems. Home steam humidifiers are on the market, though, so why not be the first one on your block?
Another type of central unit, the spray/atomizer humidifier, is also noteworthy, although not in widespread use. This type of humidifier uses a fine nozzle to spray mist into the air stream. However, it demands very clean water, precise product engineering and close maintenance. If the nozzle gets partially plugged by minerals in the water, the mist can get converted into a stream of water that causes leaks and water damage.
Evaporative cool mist humidifiers. Some evaporative cool mist humidifiers can also cover an entire home. This is the least expensive type of whole house humidifier you can buy, but it requires daily attention. You won’t need professional installation, but you can’t necessarily count on a long product lifespan. Sold off the shelf at home improvement stores, these plug-in electrical standalone units use their own refillable water reservoirs to produce a cool vapor that raises the humidity level in the home.
Whole house cool mist humidifiers come with powerful fans and large water reservoirs. These products work by drawing water into a wick and then using the fan to evaporate the water and distribute the moisture. Filtering technology screens out impurities in the water. It’s easy to set these up, but you must clean them by hand often and replace the filters regularly. Also, expect to refill it with water every day or two.
Another type of portable cool mist humidifier uses ultrasonic vibration to break up water into tiny particles and then send the moisture into the air. These units don’t use fans, however, and are only good for use in a single room.
Warm mist portable humidifiers are also available. Warm mist units use an internal heating element to boil water. They then release a warm vapor into the air. Yet warm mist humidifiers do not have fans, either, and are designed to deliver moisture to a single room only.
The best whole house humidifiers
Most advanced humidifier for large houses
Aprilaire 800 Whole House Steam Humidifier
Ideal for big homes, this is an industry-leading steam humidifier with highly advanced capabilities and nearly hands-free operation. At 24.5 pounds, the lightweight unit can cover up to 6,200 square feet in a tightly built house, meaning a home that is well sealed for energy efficiency. The model 800 adds 11.5 to 34.6 gallons of moisture to the air each day.
Aprilaire’s latest innovations for steam humidifiers introduce electrode technology to the product lineup. These innovations make their first appearance in the model 800. Under Aprilaire’s new approach, the humidifier contains a canister which is submerged in water. Electrodes inside the canister transmit electrical current to each other. The electrical current heats the water, creating steam. The Aprilaire 800 also comes with dual sensors for monitoring and responding to both indoor RH and outdoor temperature, producing optimal humidification. The unit is fully automatic, so there’s no need for manual control, although it can be installed in manual mode if you prefer. On the downside, though, the Aprilaire 800 must be installed into HVAC ductwork.
Filters are not involved because the electrode technology actually requires water impurities in order to function. No cleaning is required, but you must replace the canister once a year. Product dimensions are 7.1 x 10.1 x 20.9 inches. Pricing for an installation kit is $657.49 on Amazon. The system comes with a five-year limited warranty.
Best high-end humidifier for ductless HVAC
Aprilaire 865 Ductless Automatic Steam Humidification System
If you don’t have a forced air HVAC system, or if you just don’t like dealing with ductwork, this steam humidifer could be for you. Features and other specifications are almost the same as for the model 800, except that the 865 comes with its own wall mount fan. The fan adds to the weight of the product, as well as to the price tag. But it’s easier to set up and maintain because it doesn’t need to integrate with ductwork, which can raise its own issues, including mold accumulation in the ducts.
You’ll find a few other differences between these two models: While the controls on the 800 are automatic, the 865 must be manually controlled. The 865 comes with only one sensor, not two. Outdoor temperature is not monitored.
Still, if you want a high-end humidifier, there isn’t much not to like here. Aprilaire aims this product in particular at arid desert regions and at homes with radiant or baseboard heating, but there’s not much reason you can’t install it no matter where you live. The model 365 weighs in at 34.5 pounds. An installation kit is $999.95 on Amazon. Aprilaire provides a five-year limited warranty.
Most hassle-free fan-powered humidifier
Honeywell HE360A1075 Whole House Humidifier
This economical fan-powered evaporative pad humidifier from Honeywell is a DIYer’s dream come true. The unit uses a powered flow-through design which flushes away minerals, dust and other impurities as the water moves through the system. Consequently, cleaning is only necessary once a year.
The unit is typically mounted on either the warm air supply or return air duct of a forced air furnace. An adjustable humidistat with variable speeds is then mounted in the duct and wired to the unit. After installation, whenever the built-in saddle valve opens to let water into unit, some of the water saturates the pad. This water is then evaporated by the fan. The remainder of the water flows down the drain, meaning that no water is ever stored in the unit.
Much water can get wasted, but some customers say they have overcome this problem by installing a valve on the water inlet. It plugs into a standard electrical outlet. The 18-pound humidifier measures 10.25 x 14 x 15.25 inches. Priced at $199.95 on the Honeywell site, the installation kit comes with a one-year limited warranty.
Slickest bypass humidifier
Aprilaire 600 Automatic High Output Furnace Humidifier
A bypass humidifier offers quieter operation than a fan-powered unit and saves on energy costs by not requiring electricity. Like the Aprilaire 800 steam humidifier, the Aprilaire 600 includes an outdoor temperature sensor and allows for completely automatic operation. For every change in outdoor temperature of 2%, the Aprilaire 600 adjusts RH by 1%.
This bypass humidifier installs into the cold air return duct of your forced air furnace system. According to Aprilaire, water is piped into a distribution tray at the top of the humidifier. It is then distributed across the tray through an outlet system, flowing by gravity over the pad evaporator. Hot dry air from the HVAC system travels through the moistened pad. Evaporation occurs naturally, the water converts into vapor, and the moistened air is circulated throughout the house.
The Aprilaire 600 covers a tightly built house up to 4,000 square feet. Pricing for an installation kit starts at $139.99 on Sylvane.com. The system includes a five-year limited warranty.
Most feature-packed humidifier
Emerson HSP2000 Whole House Steam Humidifier
Covering spaces of up to 4,500 feet and producing up to 13 gallons of moisture daily, this steam humidifier from Emerson offers loads of useful bells and whistles. Although the humidifier must be used with air ductwork, the system comes with a built-in thermostat which activates the relay to turn on the blower even when the furnace isn’t running.
A saddle valve lets water flow slowly into the unit. An automatic flush timer purges the water every two hours to ward off buildup of mold and minerals. Duration of the flush can be adjusted between 10 and 20 seconds. A built-in filter captures impurities that might jam up the unit. A thermal bimetallic switch turns on the blower when the boiling water begins to steam.
A steel frame mounted to the ductwork slides out smoothly when maintenance is required. That’s a good thing, because this model requires more attention than most: Emerson recommends routine maintenance every one to three months to further prevent mineral buildup. Also, if you don’t get the unit installed by a professional, you may nullify the two-year limited warranty. The product measures 7.6 x 12.5 x 12.6 inches and weighs 18.1 pounds. Pricing for an installation kit is $836.50 and up on Amazon. Emerson offers a two-year limited warranty.
Best looking humidifier
AirCare Whole House 3.5 Gallon Pedestal Evaporative Humidifier
Appearances count, too, particularly in a smaller home where a humidifier is likely to stand out visibly. This pedestal humidifier comes with a stylish surface insert which makes the unit almost resemble a piece of furniture. It works by moving dry air through a saturated wick to produce a mist. The humidifier contains a nine-speed motor with digital controls and display. A filter is included, too. Remote control is optional.
Note that this unit only covers up to 2,400 square feet. Daily output is up to 7.4 gallons of moisture. Because water capacity amounts to just 3.5 gallons, you will need to refill it about once every two hours. Open the front pour-in door to refill the system. Other features include water refill and check light indicators.
The manufacturer suggests use with a ceiling fan to help distribute the moistened air. Product dimensions are 27.5 x 18 x 18 inches, and the unit weighs 27.5 pounds. Pricing is $149.99 at Home Depot. The nice-looking pedestal humidifier comes with a two-year limited warranty.
Simplest humidifier for medium-sized home
AirCare 3.6-Gallon Evaporative Humidifier for 3,600 Square Feet
If you own a medium-sized home, you might opt for the fancier features and longer durability of a steam or evaporative pad humidifier. On the other hand, you might find that the convenience and affordability of a cool mist model is a fine fit for your family’s needs.
The AirCare 3.6 gallon humidifier uses the same saturated wick technology as the pedestal model described above. This is a console rather than a pedestal model, though, and it provides coverage for up to 3,600 square feet. It’s equipped with casters, so you can easily move it around the house. The humidifier provides up to 11.4 gallons of moisture daily. Other features include digital control and display, a replaceable filter, four-speed motor and auto mode.
As with the 3.5-gallon pedestal model, though, frequent refills are needed — every 36 hours, but there are water refill and check filter prompts. The console system comes with refillable water bottles. The humidifier weighs 14 pounds. Dimensions are 20.5-by-21.5-by-1.5 inches. Pricing is $124.99 at Home Depot. AirCare backs the product with a two-year limited warranty.
Best humidifier for small home
Honeywell HEV685 Top Fill Cool Moisture Humidifier
Suited to use in multiple rooms, this cool mist humidifier from Honeywell is also super simple. This console unit is based on Honeywell’s wick filter technology, in which a wick doubles as a filter. It comes with adjustable controls, three output settings, and two removable 1.5 gallon water tanks.
Translucent water tanks let you see how much water is left at a glance. Other features include a refill light and humidity indicator. The system runs for up to 24 hours without a refill, and the humidistat automatically turns off the humidifier if it runs out of water.
You can refill the tanks right where they are with a pitcher of water or carry them over to the sink. The wick filters are replaceable. Weight is 13.7 pounds and dimensions are 21.3 x 13.6 x 13.7 inches. Pricing is $114.95 on Honeywell’s website. The company provides a three-year limited warranty.
How We Chose the Best Humidifiers
Considering all the central and portable humidifier units on the market these days, we reviewed only humidifiers from the most trusted brands and only those which have also received high scores on customer rating sites. From these best-of-breed products, we chose a selection that meets a whole spectrum of customer needs including home size, unit cost, maintenance and installation. If you’re interested in a high-end solution, for example, check out the Aprilaire 800 or 865 and Emerson HSP2000. If you’re a DIYer seeking a midrange solution, the Aprilaire 600 and Honeywell HE360A1075 are both great choices. If your home isn’t huge and you want a simple approach, take a look at the three portable units on our list.