Best Furnace Humidifier

If you have a dry climate in your area, you know that desert-dry air can be a problem during peak summer and cold winters. Dry air can dehydrate your skin, irritate your nose and eyes, and make breathing uncomfortable, among all its harmful effects to your health and your home. To help maintain optimal levels of humidity throughout your home, furnace humidifiers add moisture to the air that circulates. 

To help you find the best furnace humidifier, we’ll discuss the most important features of these units. The first thing you must consider is the type of humidifier, which affects the price and installation needs. The size of your home must also be taken into account so that you know the maximum daily moisture output to look for. Additionally, consider the physical size of the unit to make sure it can fit in your furnace room.

Keep reading for detailed reviews of our top picks for the best furnace humidifier. Next, we have put together a buying guide which includes features and some tips to help you choose the right furnace humidifier for your home.

Furnace Humidifier Comparison Chart

Aprilaire 700
Aprilaire 700M Humidifier



Type: Fan-powered
Coverage: 4,200 sq ft.
Maximum Daily Output: 18 gallons per day
Dimensions: 10.34 x 15.91 x 18 inches 15.5 Pounds
Aircare MA1201
AirCare MA1201 Humidifier



Type: Console-style evaporative
Coverage: 3,600 sq ft.
Maximum Daily Output: 12 gallons per day
Tank Capacity: 3.6 gallons
Dimensions: 14.5 x 21.5 x 20.5 inches14 pounds
Aprilaire 500
Aprilaire 500M Humidifier



Type: Bypass
Coverage: 3,000 sq ft.
Maximum Daily Output: 12 gallons per day
Dimensions: 10.25 x 15.63 x 13 inches
Weight: 7.75 Pounds
Honeywell HE360A
Honeywell HE360A Humidifier



Type: Fan-powered, flow-through
Coverage: 4,200 sq ft.
Maximum Daily Output: 18 gallons per day
Dimensions: 10.25 x 15.25 x 14 inches
Weight: 18 Pounds
Honeywell HE240A
Honeywell HE240A Humidifier



Type: Bypass
Coverage: 3,000 sq ft.
Maximum Daily Output: 16 gallons per day
Dimensions: ‎15.75 x 9.5 x 15.75 inches
Weight: 5 Pounds

The Best Furnace Humidifiers of 2021

Aprilaire 700

Aprilaire 700M Humidifier

Aprilaire is a leading brand of whole-home evaporative humidifiers and other indoor air quality solutions such as dehumidifiers and air purifiers. The Aprilaire 700 humidifier is rated to cover up to 4,200 square feet with a maximum output of 18 gallons of water per day. It’s designed with a built-in fan which pulls heated air directly from your furnace.

This automatic humidifier has dual sensors which will monitor and adjust operation settings depending on the outdoor temperature and indoor relative humidity. Through manual or automatic controls, it can deliver optimum humidity throughout the home with minimal supervision. The Aprilaire 700 humidifies your home to the optimal 35% – 45% RH levels, effectively reducing the risks of allergy or asthma symptoms and other respiratory issues.

This unit is considerably larger than the rest of our picks, which can make it difficult to fit in your furnace room. Before you make any purchase, always check whether you have enough space for the unit. Also note that this humidifier will be difficult to install on your own with little electrical knowledge. The manufacturer strongly recommends hiring a licensed contractor for the installation, which may add a few hundred dollars to the costs. This is important because the five-year warranty on the product will not be honored if the problem occurs after your DIY installation.

PROS

• Best for large homes
• With built-in fan
• Manual or automatic controls

CONS
  • Requires professional installation
  • Bulky build

AIRCARE MA1201

AirCare MA1201 Humidifier

Another fan-powered model in our list, the AIRCARE MA1201 console-style furnace humidifier adds cool mist (instead of steam) to the environment. It can humidify up to 3,600 square feet and delivers a maximum output of 12 gallons per day. Dry air is drawn in through the sides, then moisture is added as it passes through the saturated wick in the reservoir. The cool mist is released by the fans on the top side.

The tiny display panel shows the current humidity, your set humidity, and the selected fan speed. Set your desired humidity between 25% and 65% RH and the built-in humidistat will maintain this level. One of the best features of this model is the four fan settings: High, Medium, Ultra Quiet, and Auto. As you may have already guessed, High speed will release more moisture, while Ultra Quiet is the lowest speed. By default, the humidifier is set to 65% RH and Ultra Quiet. If you select the Auto setting, the humidifier will automatically manage its speed to maintain your desired humidity setting. It will run at High speed if room humidity is at least 10% below your setting, Medium speed if room humidity is 5% to 10% below, or Ultra Quiet if room humidity is 5% or less below your setting.

To maximize run time, fill up both the bottle and the base. When both are empty, the Refill code will flash on the display and the humidifier will operate in Auto Dry Out mode in which it runs at the lowest speed until the wick is fully dry. Additionally, after 720 hours of operation, the Check Filter alert will display. While both installation and operation are easy tasks, you must note that this unit is not the most ideal for humidifying multiple areas at once.

PROS

• Quick installation
• Easy to use controls
• Multiple fan settings

CONS

• Not the best for multiple rooms and floor levels
• Need to refill tank

Aprilaire 500

Aprilaire 500M Humidifier

For smaller homes and those on a budget, this bypass furnace humidifier from Aprilaire is our top recommendation. The Aprilaire 500 can cover up to 3,000 square feet of area in tightly sealed homes, or 1,000 square feet in loosely sealed homes. It delivers up to 12 gallons of moisture per day to help maintain optimal humidity levels. 

This model comes with a built-in bypass damper and options for right or left discharge to make installation and operation easier. It’s also equipped with a built-in drain so that there is no standing water and mineral buildup inside the machine. Cleaning and maintenance are also made easier and faster — most will require a simple once-a-year routine cleaning. 

Aprilaire humidifiers work by feeding water into the distribution tray at the top of the unit. The water is distributed evenly around the tray and through a network of outlets. It pours across the Water Panel evaporator via gravity. The moisture-laden Water Panel evaporator receives dry, heated air from the HVAC system. Natural evaporation occurs, converting the water to vapor, and the humidified air circulates throughout your home.

To ensure proper humidification, replace the Water Panel twice a year. Each model includes an indicator that alerts you when it’s time to replace it. Remember that Aprilaire strongly advises that these units be installed by a qualified HVAC professional.

PROS
  • Affordable price
  • Small but effective
  • Manual or automatic controls
CONS

  • Manual or automatic controls
  • Honeywell HE360A

    Honeywell HE360A Humidifier

    If we’re talking about fan-powered furnace humidifiers, we need to include the Honeywell Home HE360 Flow-Through Humidifier. This furnace humidifier covers areas as large as 4,200 square feet with a maximum output of 18 gallons per day. The included humidistat can be mounted on the duct or wall for easy humidity control.

    This Honeywell humidifier works on the principle that vapor is produced when warm air is blown over a wet area. The relative humidity rises as the vapor circulates; the humidity control monitors the relative humidity and activates the humidifier as needed. The humidifier has a water supply that evenly distributes water over a humidifier pad. The dry-heated air from the furnace passes over the humidifier pad and collects moisture to circulate it throughout your home.

    This easy-to-install HE360 whole-house humidifier does not require bypass ducting. You can mount the system directly onto your forced-air furnace using the included installation kit and instructions. Its flow-through design helps keep the unit clean for longer. Also, the PerfectFLO distribution tray ensures thorough saturation of the humidifier pad and uniform distribution of moisture for optimum energy efficiency and water usage. Although, note that you’ll need a floor drain to provide drainage for the condensate. Like most Honeywell products, the humidifier comes with a one-year warranty. 

    PROS
    • Easy to install
    • Simple to use
    • Affordable price
    CONS
    • Requires floor drain
    • One-year warranty

    Honeywell HE240A

    Honeywell HE240A Humidifier

    The last spot in our list goes to the Honeywell HE240 Bypass Humidifier. This whole-house humidifier covers up to 3,000 square feet, providing a maximum of 16 gallons of moisture per day. 

    This whole house humidifier works with your forced-air furnace to distribute moisture throughout your home. If you have the necessary tools, you can easily mount the unit onto the warm air supply or return air duct of your furnace and connect it to a drain line. The HE240 also includes an easy-to-use humidity control that monitors relative humidity and activates the humidifier as needed.

    Warm air from your furnace blows over a wet evaporator pad to create vapor, which is then released through your air ducts to circulate throughout your home. Honeywell’s unique design helps keep the unit clean by routinely rinsing and draining itself instead of collecting stagnant water inside the machine. And if you have hard water, the evaporator pad helps filter out minerals and other impurities so that it distributes only clean air.

    PROS

    • Easy to install
    • Simple to use
    • Affordable price

    CONS
    • Requires floor drain
    • One-year warranty

    Why You Need a Furnace Humidifier

    Furnaces produce warm and dry air, which can be harsh on your skin, eyes, nose, and respiratory system. This can lead to colds, sore throats, dry lips and skin, and all sorts of respiratory infections. Furthermore, dry air can also affect your belongings and the very structure of your house. It pulls moisture from wooden materials–the frame of your home, for example, causing gaps between walls and ceilings.

    To prevent these problems, furnace humidifiers add moisture to the air that circulates throughout your home. They help maintain ideal humidity levels, making the environment more comfortable for you, while also hydrating your plants and wood floors.

    Of course, you have the option to use portable humidifiers instead. However, these units only work effectively in individual rooms. If you have a large house with multiple rooms and floor levels, you will have to buy several portable humidifiers for each room to maintain proper humidity everywhere. Meanwhile, with a single furnace humidifier you can do this for the entire house in one operation.

    How Do Furnace Humidifiers Work?

    There are different types of humidifiers, but they work by a similar principle of humidification. A furnace humidifier takes moisture from a water supply and evaporates it into a warm airstream coming from the furnace. Water is supplied to the humidifier through a saddle valve. The volume of water to be supplied is controlled by an inlet valve that is then controlled by a solenoid which is further controlled by a humidistat. When the humidity setting is increased through the humidistat, the solenoid turns on and water is fed into the humidifier. 

    The water inlet on top of the humidifier delivers water to a tray which distributes water evenly across the evaporator pad. The water evaporates and the minerals are deposited on the pad itself. You may see the collection of minerals in a white powder coating over the evaporator pad after a certain period of usage. You will then need to clean the evaporator pad or replace it, as per the manufacturer’s instructions.

    How to Choose the Best Furnace Humidifier

    Type

    Fan-Powered Furnace Humidifiers

    Fan-powered or evaporative humidifiers work simply by passing the furnace-heated air over water. The hot air evaporates, increasing the level of moisture in your ducts. This type of humidifier requires minimal maintenance and is typically easy to install. You’ll just have to change the filter or water panel once or twice a year, depending on the model. With a built-in fan, moisture is distributed directly to the house, saving on your water and electricity bills. You can even operate your evaporative humidifier while the furnace isn’t in use. 

    Bypass Furnace Humidifiers

    Bypass humidifiers are less expensive than evaporative humidifiers since they don’t come with a fan or steamer. They are connected to the return duct of your furnace and rely on the blower motor to push the heated air. Moisture is then added to the air then recirculated to the furnace, causing some of the humidity to be lost in the process. However, a bypass furnace humidifier makes less noise since there’s no fan. There are also fewer moving parts in a bypass furnace humidifier, thus requiring less maintenance.

    Coverage 

    The area of coverage, usually measured in square feet, refers to the total size of the house that a furnace humidifier is rated to work effectively. Using a smaller humidifier in a house that is too large for it will make the task much harder for the unit, equating to higher bills and an ineffective unit. On the other hand, using a larger humidifier than you need for your total area will be a waste of water and electricity.

    Maximum Daily Output

    The maximum daily output is the volume of water that your dehumidifier can evaporate into the heated air in 24 hours while running at its highest setting. A higher rated output typically means a larger area of coverage, but it can vary depending on the manufacturer. In general, an output of at least 16 gallons per day should be enough to cover most 3,000 to 4,000 square feet areas. Also keep in mind that a higher output equates to a higher energy consumption. Therefore, a higher output humidifier may increase your electricity and water bills.

    Size and Weight

    The physical dimensions and weight of your humidifier will also be an important consideration if you need to install it in a cramped furnace room or carry it into your attic or basement. For example, if you have limited space in your furnace room, you may want to look for a smaller and lighter humidifier.

    How to Install a Furnace Humidifier

    Most furnace humidifier units come with all the components needed to install them into your furnace system, but doing it yourself requires a few other tools and equipment, as well as some experience in ductwork. 

    The installation process typically involves the following steps: You will first need to tap into a cold-water line with the included saddle valve. Then, connect the wiring to the furnace and cut a hole in sheet metal to fit the humidifier. Finally, attach the humidifier to the sheet metal and hook up the wiring and plumbing.

    If you’re not absolutely sure you can do all this, the best choice is to hire an HVAC professional with the necessary tools and experience for a safe and proper installation of your humidifier.

    Furnace Humidifier Maintenance Tips

    Furnace humidifiers require little to no maintenance since the constant heat inhibits mold growth. Most of these humidifiers also have a filter or evaporator pad to eliminate mineral buildup. You will need to replace the filter at least once to twice a year, or as instructed by the manufacturer. 

    To reduce the risk of fire or damage to humidifiers, only use cleaning agents specifically made for humidifiers. Never use flammable, combustible or poisonous materials to clean your humidifier, and do not put hot water in the unit. If using fan-powered humidifiers, they may be more prone to mechanical issues, so always check to make sure the fan is working properly.

    FAQ

    What humidity level should you set your furnace humidifier at in the winter?

    When outdoor temperature drops to 10°F to 20°F, adjust your humidity setting to 25% RH. If your dehumidifier does not feature automatic controls, you may have to monitor outdoor temperatures yourself. Or simply set the humidity around 40% to 50% RH, then adjust the setting when you start to notice condensation on your windows and walls.

    How much does it cost to add a humidifier to your furnace?

    At the time of writing, the cheapest unit we recommend is around $120, and the largest models go up to $300. Depending on the add-ons you want to purchase, including tools and professional installation, the costs can rack up to $1000 or more.

    How long do furnace humidifiers last?

    With proper care and maintenance, your furnace humidifier can last five up to ten years.