Are you looking for a new furnace humidifier?

You’re in the right place! In this proHVACinfo review, we cover:

  • What is a furnace humidifier (and surprising problems they solve)?
  • The various types of furnace humidifiers (and which is right for you)
  • How to choose the right furnace humidifier (avoid the fluff and focus on these 3 things)
  • The best furnace humidifiers (2021 review)

Before our deep dive, let’s take a quick look at some of our favorite furnace humidifiers.

Our Top 4 Furnace Humidifiers

  1. Aprilaire 700 Automatic Fan Powered Furnace Humidifier (Our Top Pick)
  2. Aprilaire 400 Whole Home Furnace Humidifier (Best Budget Pick)
  3. GeneralAire 1000A, 120V Furnace Humidifier (Best High End)
  4. Honeywell HE360A1075 HE360A Furnace Humidifier

What Is a Furnace Humidifier?

A furnace humidifier is a special piece of equipment connected to your furnace ductwork to add moisture to the air in one room or an entire building.

Said simply, furnaces can really dry out the air you breathe, and a humidifier counteracts that drying effect.

We’ve all had the uncomfortable experience of breathing dry air (think of a cold winter morning, for example). But did you know that dry air can cause more serious problems?

According to the National Institute of Health, dry indoor air can affect pets and people. It can even cause nosebleeds, allergies, and respiratory infections.

A furnace humidifier optimizes your furnace by fostering the proper distribution of moisture throughout the building, which prevents the negative effects of dry air.

Now that you understand what furnace humidifiers do at a high level, let’s look at some of their other benefits.

Protect Furnishings

If you’re a homeowner, you’ve probably noticed this in the winter, when your heater kicks on:

Your floors squeak, furniture creaks, and you get a nasty shock seemingly every time you touch a doorknob.

Did you know that dry air is what’s causing each of these issues? A furnace humidifier preserves wood by stabilizing your home’s humidity level. Maintaining proper humidity levels protects wooden cabinets, flooring, ceilings, and furniture from drying out and cracking. It can also reduce static electricity.

Comfort during Winter

When it comes to your personal comfort, you’ll really notice the difference your furnace humidifier makes during the cold winter months, when the air is especially dry.

Connecting a humidifier to your furnace will ensure a proper amount of moisture circulates throughout your home or office, which will definitely increase your overall comfort level.

What Are the Different Types of Furnace Humidifiers?

  1. Drum Humidifiers – Also known as a reservoir humidifier, this type of humidifier has a pan of standing water and a rotating drum attached to an evaporative pad. The drum passes through a pan where the pad absorbs the water.

The drum humidifier works by evaporation; the water from the moistened pad evaporates into the air. We recommend this type for homeowners who want a balance of installation ease and efficiency in converting all supplied water into humidity.

  1. Flow-Through Humidifiers – Similar to drum humidifiers, flow-through humidifiers also work by evaporation. Both humidifiers have several features in common; the difference is the water source. Rather than using a water pan, the flow-through humidifier has a steady water stream consistently running across the evaporator pad.

Flow-through furnace humidifiers generally have a more involved installation process, and are about 30% to 40% efficient.

  1. Steam Humidifiers – These furnace humidifiers have a steam machine that uses electricity to cause evaporation. Steam humidifiers are slightly more expensive than the other types, but the benefit is that they’re more efficient. Steam humidifiers generally have 100% efficiency (i.e. 100% of the water used in the humidifier is converted to moisture). For that reason, we recommend steam humidifiers for the more environmentally-conscious consumer.

How Do Furnace Humidifiers Work?

Furnace humidifiers add moisture in the air by transforming water into vapor and circulating it through the home’s furnace ventilation system.

The humidifier has a humidistat used to set and maintain a desired moisture level in the building by turning your humidifier on and off as required.

The humidifier is often connected to a water source, the ductwork and mounted to the hot air supply of the furnace to work in conjunction with the furnace and with the help of other necessary humidifier parts.

What Do You Look for in the Best Furnace Humidifier?

When shopping for a new furnace humidifier, there are 3 big things to consider.

  1. The Capacity
  2. The Controls
  3. The Features

The Capacity

You want to be sure the humidifier you purchase is powerful enough to cover your entire home.

“Great,” you might think “I’ll get a humidifier with the highest wattage I can afford.”

Don’t make this mistake! According to the EPA, there is very little, if any, correlation between humidification capacity and watt rating.

The metric you should really care about is gallons per day (“gpd”).

A model rated at 1.5 to 2.0 gpd is good up to 500 square feet, while a rating of 3.0 to 3.5 gpd will fit a 700 to 800 square feet space.

If your home is between 1000 and 2000 square feet, you’ll require a unit rated at around 7.0 to 9.0 gallons per day. A space measuring more than 2000 square feet will work with a model rated at 10.0 gallons per day or higher.

If you aren’t sure about which capacity to pick, you can use the humidification calculator to get a more specific estimate.

The Controls

Ensure the furnace humidifier you choose has an easy-to-read and adjustable humidistat for maximum convenience. The humidistat works similarly to the thermostat on your furnace.

The only difference is that it measures the moisture levels rather than temperature.

If you find a model without a built-in humidistat, you can opt for a unit that comes with a separate SMARTRO Thermo-Hygrometer to let you measure the humidity level. However, in this case, you’ll have to adjust your furnace humidifier manually.

The Features

As with many other household appliances, the technology offered in furnace humidifiers is evolving rapidly. It’s easy to get swept up in unnecessary features that don’t actually matter.

Below are the features that really matter when making your decision, once you strip away all the fluff.

  1. Auto shut-off – This is an important feature that prevents the humidifier from breaking down prematurely, by shutting down automatically when the water source is depleted.
  1. Water tank indicator – Look for a furnace humidifier that indicates the water levels to let you know when to refill the reservoir.
  1. Humidistat – Ensure you pick a furnace humidifier with a humidistat that turns the unit off after reaching the set/desired humidity level.
  1. Filter Indicator – Be sure to look for a humidifier with this feature as it helps you know when the filter is clogged and either needs cleaning or replacement.

The Top 4 Furnace Humidifiers (Reviewed)

  1. Aprilaire 700 Automatic Fan Powered Furnace Humidifier (Our Top Pick)

The Aprilaire 700 Automatic Fan Powered Furnace Humidifier is a drum humidifier with a modern design and smart features. Its dimensions are 16 x 11 x 18 inches.

It provides 18 gallons of moisture per day, making it sufficient for insulated spaces measuring up to 4,200 square feet.


  • Large capacity
  • Easy installation
  • “Set it and forget it” product
  • Water, filter, and other crucial indicators monitor unit status
  • Minimal noise
  • Easy cleaning and maintenance


  • High water consumption

  1. Aprilaire 400 Whole Home Furnace Humidifier (Best Budget Pick)

If you’re looking for a furnace humidifier for a mid-size room, this is your best choice. The Aprilaire 400 Whole Home Furnace Humidifier is the less-powerful cousin of our #1 pick. Another drum humidifier, it can moisturize houses sized between 1,200 to 4,000 square feet with a capacity of 17 gallons per day.

This device does an impressive job in sealed spaces, such as a typical mid-sized home. What’s more, it gives you easy control at your fingertips – you can adjust humidity levels manually or set your desired level and let the machine maintain it.


  • Good value
  • Reversible side panels
  • Low water consumption
  • Automatic humidifier included
  • No floor drain required


  • Not suitable for coverage of large areas
  • DIY installation can void the warranty

  1. GeneralAire 1000A, 120V Furnace Humidifier (Best High End)

The GeneralAire 1000A, 120V Furnace Humidifier, is a modern fan-powered humidifier with dimensions of 20 × 19 × 18 inches. This device has a fan inside that pulls warm air through its highly-evaporative vapor pad, where the warm air is moisturized.

The humidifier has a built-in humidistat, which allows you to pick the desired settings and leave it to monitor and keep the humidity at the assigned level. We recommend this model for spaces up to 3,000 square feet.


  • Auto-mode
  • A powerful internal fan
  • Thermostat
  • Outdoor temperature sensor
  • Long warranty (5+ years)
  • Water and filter indicators


  • DIY installation or repair voids
  • A bit noisy
  • High water consumption
  • Bulky

  1. Honeywell HE360A1075 HE360A Furnace Humidifier

If you live anywhere with a dry climate, the Honeywell HE360A1075 HE360A Furnace Humidifier is for you. This humidifier is effective for areas sized up to 4,200 square feet.

The Honeywell HE360A1075 Whole House Humidifier features a PerfectFLO distribution Humidifeir features tray, designed to optimize efficiency and water usage (so it’s a great choice for the thrifty consumer!)


  • Digital humidistat included
  • Compact size
  • Easy to install
  • Good coverage


  • Short-duration warranty
  • The installation kit is bought separately

Final Thoughts on the Best Furnace Humidifiers

The use of furnace humidifiers helps you save money on energy bills, stay cozy, and improve your family’s health by increasing moisture in the air, especially when the temperatures drop. The top furnace humidifiers mentioned above are designed to provide maximum efficiency in delivering the desired humidity level inside your home or office.

Stephen Marks

Stephen Marks

Stephen is an HVAC and home-repair enthusiast. He's here to answer any of your questions about HVAC!

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Stephen Marks

Stephen Marks

Stephen is an HVAC and home-repair enthusiast. He's here to answer any of your questions about HVAC!

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