6 Best Furnace Humidifiers – Reviews & Buying Guide 2021

For most people, a standard portable humidifier is enough to raise indoor humidity to desired levels. However, in a few cases, especially in large homes located in very cold areas, a single portable humidifier might not be sufficient.

In such situations, rather than buy several small humidifying units, it might be better to invest in the best furnace humidifier.

This guide is designed to help you determine whether a furnace humidifier would be right for you and, if so, aid you in selecting the right one for your home. First, though, a review of the best whole house furnace humidifiers

Best Furnace Humidifier Reviews 2021

Last update on 2024-06-15 / Affiliate links / Images from Amazon Product Advertising API

 1. Aprilaire 800 Whole House Steam Humidifier

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The most expensive option on this list and one of the very best furnace humidifiers in the market, the AprilAire 800, is a beautifully-designed and easy-to-install evaporative humidifier. The humidifier uses electrode technology where an electrical current is passed between submerged electrodes, and the resistance of the water to electric current causes the water to heat up.

Aprilaire has taken vital steps to make the unit both safe to use and easy to maintain. For one, the submerged electrodes are located in a replaceable canister where they can’t harm you. Secondly, the only maintenance required of you is to replace the canister (including the electrodes) at the end of the heating season. Water filtration isn’t required.

The humidifier is designed for homes up to 6,200 square feet (equal to two average-sized homes) and offers six output levels that add between 11.5 and 34.6 gallons of moisture to air every day.


  • Employs efficient electrode technology 
  • Purified/filtered water not required
  • Designed for up to 6,200 square feet
  • Features truly automatic control


  • Most expensive product on this list


2. Aprilaire 700 Whole House Fan Powered Humidifier

AprilAire 700 Whole Home Humidifier, Automatic Fan...
  • BUY WITH CONFIDENCE This humidifier was designed and manufactured in the USA by AprilAire – the inventor of the whole home evaporative humidifier, and the leader in indoor air quality solutions
  • FULL COVERAGE up to 5,300 square feet in tightly built homes with a capacity of 18 gallons per day
  • AUTOMATIC HUMIDIFIER with dual sensors to monitor and respond to both outdoor temperature and indoor relative humidity to deliver optimum humidity 24/7 throughout the home – simply set it and forget it
  • BUILT-IN FAN pulls heated air directly from the furnace through the humidifier
  • HUMIDITY FOR HEALTH AprilAire Humidifiers can help you maintain optimal humidity in your home of 40% – 60% which has been shown to reduce the incidence of respiratory infections and symptoms related to allergies and asthma by minimizing the formation of bacteria and viruses, fungi, and dust mites. In addition, you’ll feel more comfortable while also preserving items in your home susceptible to damage from changing humidity or dry conditions

Last update on 2024-06-15 / Affiliate links / Images from Amazon Product Advertising API

Another AprilAire on the list, this time a slightly smaller (capacity-wise) option, the Model 700 is just as effective as Model 800 above, except that it’s designed for smaller spaces. At full speed, the humidifier can efficiently supply moisture throughout a 4,200 square feet space. It produces up to 18 gallons of moisture each day.

Another thing you may want to know about Model 700 is that it’s a fully automatic humidifier. It has dual sensors and quickly responds to both outdoor temperature and relative humidity to ensure that you have a comfortable indoor climate round the clock. 

Other features of the Model 700 include a built-in fan (thus fan-powered) and convenient digital control. The digital display shows the current relative humidity in your home. It also has lights to indicate when the humidifier is running, when service is needed, and when the water panel needs changing.


  • Built-in fan
  • Digital control
  • Fully automatic
  • Covers up to 4,200 square feet


  • No clear instructions for DIY installation 


3. Honeywell HE360A1075 HE360A Whole House Humidifier

Honeywell Home HE360A1075 HE360A Whole House...
  • Powered flow-through humidifier
  • Easy installation and best choice for variable speed and multi-stage systems in homes up to 4,200 square feet
  • Easy mounting on either warm air supply or return air duct of any forced-air furnace
  • Flow-through design helps keep unit clean and decreases the frequency of maintenance
  • Installation kit required (sold separately)

Last update on 2024-06-14 / Affiliate links / Images from Amazon Product Advertising API

If you don’t want to drain out excess water from your furnace humidifier constantly, a flow-through model such as the Honeywell HE360A1075 would be a wise investment. The flow-through design keeps the humidifier clean and lowers the frequency of maintenance. 

Additionally, the HE360A1075 used a PerfectFLO distribution tray that optimizes efficiency and water usage, making the humidifier one of the most cost and energy-efficient units out there.

The HE360A1075 is designed for spaces up to 4,200 square feet and easily mounts on either the warm air supply or return air duct of any forced-air furnace. 

The one major downside of the HE360A1075, however, is that it doesn’t include the required installation kit. Instead, the kit is sold separately. That said, though, the package comes with several required components, including feedwater tubing, mounting hardware, compressing rings, wire nuts, and rubber gasket. A 1-year manufacturer warranty protects the entire unit. 


  • Low-maintenance, flow-through design
  • Most required components included
  • Easy to install
  • Designed for up to 4,200 square feet


  • Installation kit sold separately 


4. Skuttle 190-SH1 Drum Humidifier

Skuttle 190-SH1 Drum Humidifier
  • Energy efficient - uses minimal water and electricity
  • Durable thermoplastic cabinet resists rust, corrosion and warping
  • Interior components designed for easy cleaning or replacement
  • Moisture output of 17 gallons per day at 120 degrees F
  • Reversible components and snap-lock fittings allow for easy installation

Last update on 2024-06-14 / Affiliate links / Images from Amazon Product Advertising API

The Skuttle 190-HS1 is an energy-efficient furnace humidifier that uses minimal water and electric power. At under $150 for the entire package, including installation kit, it’s one of the best value-for-money buys you can currently find.

The bypass humidifier features snap-lock fittings and reversible components for easy and quick DIY installation and maintenance. It has an output capacity of 17.0 gallons per day and delivers moisture at 120F.

The 190-HS1’s package contains, among others, a self-piercing saddle valve, bypass tubing, 24-volt transformer, summer-shutoff damper, start collar, mounting hardware, mounting template, and the user manual with detailed installation instructions. A Skuttle Automatic Flushing Timer is another useful feature on the 190-HS1. 


  • Energy-efficient operation
  • Moisture output of 17 gallons per day
  • Snap-lock fitting and reversible components for easy installation 
  • Durable rust and corrosion-resistant thermoplastic cabinet


  • Included bypass duct is short


5. Emerson HSP2000 Whole House Steam Humidifier

Emerson HSP2000 Whole House Steam Humidifier
  • 120-Volt steam powered whole house humidifier with flushing timer and filter
  • For use in 1400 square foot minimum house
  • Steam Powered
  • Flushing Timer
  • Rated output 13-Gallon per day

Last update on 2024-06-14 / Affiliate links / Images from Amazon Product Advertising API

For those interested in a steam humidifier, the Emerson HSP2000 would be an excellent investment. Also popular as the White-Rodgers HSP2000, this humidifier is a 120-volt, 1500-watt whole-house warm-moisture generating unit featuring a stainless steel build for durability and long-term performance.

An automatic flushing timer, washable furnace water filter, automatic humidistat, saddle valve, blower safety switch, fan control relay, and mounting frame are some of the HSP2000’s top features. 

Although steam humidifiers don’t require the furnace to be ON to operate, the HSP200 has a thermal switch designed to turn ON the furnace’s blower. Together with the digital thermostat, this thermal switch ensures that indoor air is warm and adequately humidified throughout the day.

The HSP2000 is best suited to spaces up to 1,400 square feet and delivers 13 gallons of warm moisture every 24 hours.


  • Efficient, steam-powered operation
  • Flushing timer
  • Delivers 13 gallons/day
  • Automatic humidistat


  • May nit be enough for whole-home humidification

6. Skuttle 86-UD Under Duct Drum Humidifier

Last update on 2024-06-15 / Affiliate links / Images from Amazon Product Advertising API

Finally, the Skuttle 86-UD is a drum-style whole-house humidifier designed for homes up to 4,000 square feet. It boasts a daily moisture output of 17 gallons, with the moisture delivered at 120F plenum temperature. 

The design, which combines flow-through and drum-style characteristics, allows air to pass directly to your ductwork instead of a bypass tube. This design style delivers more humidity compared to bypass humidifiers.

The 86-UD’s module is mountable on horizontal ducts as small as 12 inches wide, and the package comes with mounting frames included for easy and fast installation. The body of the humidifier is made from a sturdy thermoplastic material to resist rusting, warping, and erosion. 

The 86-UD comes equipped with one evaporator pad plus an extra replacement pad. These pads must be replaced at least once every six months.


  • Extremely efficient 
  • Low heating costs
  • Digital hygrometer included
  • Automatic flushing timer included


  • No automatic safety shutoff


Best Furnace Humidifier Buying Guide

Now that you know about some of the best furnace humidifiers currently available in the market, let’s dive into the buying guide. 

furnace humidifier installed

What is a Furnace Humidifier?

A furnace humidifier is a type of whole-home humidifier that’s installed in the ductwork connected to your home’s cooling and heating system. 

Advantages of Furnace Humidifiers

Furnace humidifiers come with a ton of benefits, the biggest of them being increased convenience. Since the humidifier is installed into the home’s water supply system, you never have to worry about refilling the system again. This is a huge relief compared to portable humidifiers that have to be refilled daily or every few days. Other than that, furnace humidifiers also offer;

  • Reduced maintenance: Since the humidifier draws water directly from the home’s water supply system, maintenance tasks common with portable units are reduced. For example, you don’t have to empty the humidifier every night and clean the tank every few days/weeks.
  • Whole-home humidification: There are indeed high capacity portable humidifiers that can serve large rooms or even multiple rooms within the home. Heck, some might even humidify an entire apartment. The reason furnace humidifiers are still better than these large capacity portable humidifiers is that, with portable units, you’ll need to refill the water tank frequently each day, or at least every few days. With furnace humidifiers, you don’t have to worry about refilling any tank.
  • They are quieter:This especially applies to bypass models (more on this shortly) that depend on the furnace’s blowing system. Since they don’t have fans, you don’t need to worry about a new noise source in the home.
  • They add to the home’s value: This is an often-overlooked advantage. Furnace humidifiers are installed into the home’s HVAC system, thus become part and parcel of the home’s structure. If you were to sell the house, the cost of the unit would be factored into the selling price. This is different from portable units that you’ll need to carry to your next house if moving. 

Types of Whole House Furnace Humidifiers 

There are three main types of furnace humidifiers; bypass, fan-powered, and steam. Here’s what you need to know about each type;

 1. Bypass Furnace Humidifiers

A bypass furnace humidifier is installed directly onto your HVAC system. It is primarily characterized by a bypass duct that draws warm air from your furnace, and it passes through a rotating water pad or panel where evaporation occurs. 

Since the system is directly connected to your home’s water supply system, the water necessary for the evaporation process naturally flows from the home’s water line into the humidifier’s reservoir system. 

Most bypass furnace humidifiers are automatic. They have a humidistat that automatically detects the relative humidity in your home. Whenever the humidistat detects low relative humidity levels in your home, it activates the humidification process. The water in the reservoir system passes over the wet belt/pad and evaporates into tiny moisture particles. The moisture is then channeled through the home’s ductwork and eventually blown into your home with the help of the furnace’s fan. 

You’ll likely come across flow-through and drum humidifiers, also listed as other types of humidifiers. Both of these are bypass humidifiers since they need a bypass duct system. The difference between the two is that drum humidifiers have a water reservoir while flow-through models don’t. All bypass humidifiers only work when the furnace is ON.

 2. Fan-powered Furnace Humidifiers 

Fan-powered furnace humidifiers are different from bypass humidifiers because they don’t depend on the furnace’s blower motor. As we saw earlier, bypass furnace humidifiers rely on the furnace’s blower fans to move air over a rotating belt, a process that’s critical to the introduction of moisture to your rooms.

Fan-powered furnace humidifiers don’t need the help of the furnace’s blower system because they come equipped with their own fan systems. As a result, fan-powered humidifiers are not only self-reliant but also faster. Thanks to the fans, they can blow about one gallon more moisture daily compared to similar bypass humidifiers. 

As you can guess, they also don’t need a special bypass duct. This makes fan-powered humidifiers easier and less costly to install. They are also simpler to maintain.

 3. Steam furnace humidifiers

Finally, you may also choose to buy a steam humidifier. Steam humidifiers, as the name suggests, boil water into steam and then pump the steam into your HVAC ductwork. The humidifiers comprise a water reservoir that is electrically heated to a boiling point, and the resulting steam fanned into your ductwork.

What usually happens is that a humidistat built into the humidifier unit monitors the relative humidity in the home. Whenever the humidity levels drop below a set point, the water reservoir is heated to produce steam. 

The biggest advantage of steam humidifiers is that the furnace doesn’t need to be ON for the humidifier to work. You can run the humidifier independently. Steam humidifiers also create more humidity than both fan-powered and bypass humidifiers. And, since the water is heated to the boiling point, all harmful microorganisms are killed, meaning that the moisture blown into your home is very healthy. Steam humidifiers are, however, also the most expensive of the lot. 

Factors to Consider When Choosing a Furnace Humidifier 

 Furnace humidifiers come in all shapes and forms. The following are the top five factors to consider when selecting one for your home;


The size of the humidifier essentially refers to the maximum area it can effectively serve. Most furnace humidifiers have a maximum area coverage rating of at least 1,500 square feet, with some having less and others more. Indeed, some go as high as 8,000 Sq. Ft. Choose a unit that closely matches the size of your home, keeping in mind that too much humidification is just as inadequate as under-humidification. For large apartment, you can choose whole house humidifiers or large room humidifiers.

Daily output

It’s easy to confuse humidifier size and daily output. A larger size doesn’t necessarily equate to higher moisture output. For output efficiency, check the unit’s daily humidity output rating. The figure is often given in gallons/hour or gallons/day. The higher the hourly/daily output, the more effective your home will be humidified at any given time. 

Ease of installation

This can be an especially important factor if you intend to DIY the installation. Options that require an additional bypass duct, for instance, are slightly more challenging to install by yourself. Not only do they need you to buy and install a new duct system, but additional insulation is also necessary. Also, keep in mind that one small mistake might void the manufacturer’s warranty. Steam humidifiers also pose multiple challenges, considering the heating elements involved.  

Convenience features

As you can tell from the reviews section, all furnace humidifiers come with a range of convenience features included to make your work easier. Some of the key features to look out for include; water reservoir change indicator, low water cutoff, automatic operation, mounting frames, reversible side panels, and overflow protection. 


Finally, you also need to consider the cost of the appliance. Humidifier prices vary depending on the type of humidifier you’re buying, the size/capacity, and the features. Drum-style bypass models are the least expensive, costing around $150 to $300. Flow-through models are slightly more costly but mostly lie in the same range. Fan-powered models tend to cost in the region of $300 to $400. And, steam models are the most expensive, often priced in the $500 to $800 range. Remember that, depending on the features, some of the humidifiers can cost up to $1,000+.

Furnace Humidifier Cleaning and Maintenance 

Furnace humidifier cleaning and maintenance procedures vary depending on the type of humidifier you choose. For drum models, for example, the wet belt/pan may experience sediment buildup over time, thus requires periodic cleaning and eventual replacement.

Flow-through and fan-powered models also require seasonal cleaning to rid the humidifier of any bacteria growth. Steam models are, by far, the easiest to maintain as all they need is end-of-season cleaning. You also choose an easy-to-clean humidifier from our guide if you’re the forgetful kind of person.


In a nutshell, furnace humidifiers would be an excellent addition to your home if you’re looking to humidify multiple rooms or an entire home. Rather than buy several portable humidifiers that would make your work difficult, you only need one furnace humidifier to service the whole household. And, you won’t need to refill any water tanks! That said, however, you still need to find the right size for your home and, ideally, have it installed and periodically inspected by a licensed HVAC professional.

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Melanie Mavery is an aspiring HVAC technician who is fascinated by the trends and opportunities in the HVAC industry. She spends most of her day writing content on home improvement topics and outreaching to prospects.  She's always looking for ways to support HVACs!