Do Furnace Humidifiers Really Work?

Grandparents Reading Kids a Story in Winter

We need our Scarborough furnaces to survive Canada’s deadly cold, but that heat comes at a price: dry indoor air.

Most people notice they get dry, itchy skin in the winter. For some, sore throats and “perpetual colds” are an issue. Dry winter air can aggravate asthma, dust allergies, and even cause nosebleeds for some people.

Properly humidified air can help alleviate some of these dry air symptoms. It can be tempting to buy a small tabletop or portable humidifier. But the only way to really solve the problem is to get a furnace humidifier installed. A whole house humidifier installed in your HVAC system is the only way to truly change the humidity level of your entire home at once.

Find out what the difference is between air purifiers and humidifiers>

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Pros and Cons of a Furnace Humidifier


Healthier Air Quality

There are plenty of health benefits that come with whole home humidification, such as allergy relief and a reduction in chapped lips, dry and cracked skin, and respiratory infections and colds.

Just be sure to maintain your humidifier properly, because there is the potential for mold or bacteria if you have too much humidity and a dirty furnace humidifier.

Maintain Humidity Control

Not only do our bodies hate overly dry air, our homes do too. Wood floors and furniture need a minimum humidity level of 35% to prevent splitting along the grain (known as “checking”).

Our bodies love more humidity – but if it gets over 35% you run the risk of mold growth. High humidity levels (over 55%) can help germs thrive and can cause wood to warp.

Low Maintenance

With whole house humidifiers, there’s no tank to fill. Furnace humidifiers connect right to your water supply line, so there’s no struggling with the weight of a larger tank, or the constant refilling that’s needed with a smaller one.

Quiet and Discrete

With a furnace humidifier, there are no boxes to clutter up the living areas of your home. You won’t be subject to the constant white noise of an in-room portable humidifier, as a furnace mounted humidifier automatically runs when your furnace does.

Adds Home Value

Healthy indoor air quality can have a big impact on your home’s value. Adding a whole house humidifier can help preserve your home with proper humidity control.

Reduced Energy Costs

Furnace humidifiers can even help you save money on heating, as moist air feels warmer, and you don’t need to keep the temperature set as high. Because the humidifier is connected to your home’s water supply, there’s less wasted water with filling portable humidifier tanks.



Like any appliance or HVAC system, there is a cost associated with whole house humidifiers. Depending on the type you want to install, you could pay anywhere from $150 to $1100 for the humidifier alone. Installation might be extra, and will vary based on the style you choose.

Air Leaks

Preventative maintenance is the key to avoiding leaky humidifiers. Your furnace humidifier filter (also called a water panel or evaporator pad) needs to be changed regularly, otherwise it will become clogged with mineral deposits, scale, and other debris that could restrict the water flow.

You should also regularly check the water flow and pressure through your home’s water supply, as too high pressure might cause leaks.

How Do Furnace Humidifiers Work?

As you might guess, furnace humidifiers install right onto your main heating and cooling system, usually in the ductwork leading out from your furnace. The hot air leaves the furnace, passes through the fan that pushes it through the ducts, and then flows past the humidifier and out into the rest of your home.

There are 3 main types of furnace humidifiers:

  1. Steam humidifiers produce either a warm or cool mist, and therefore produce the most moisture. A steam humidifier heats water using electricity to create steam, and they’re quite easy to maintain. There is almost no risk of mold.
  2. Flow through humidifiers expose the hot air from your furnace to a constant trickle of water. The water naturally evaporates into the air leaving your furnace. While there is a humidifier filter pad that needs to be changed periodically, flow through units are low maintenance overall. Again, these have almost no risk of mold.
  3. Drum humidifiers have a pan of water, and a rotating belt that passes through the pan. The water from the moistened belt evaporates into the air leaving your furnace. Because this type of humidifier has a standing pan of water, you need to be diligent about cleaning it or mold can form. This is the least expensive type of furnace humidifier.

You can install a humidifier on almost any kind of furnace system, even older ones.

How Dry is Your Winter Air?

There are some easy ways to tell if your home is too dry. Obviously, if you’re getting shocks from static electricity, it’s too dry. If you’re seeing moisture condensation on the windows (“sweat” or even frost) it’s too humid.

But to be sure, buy a hygrometer (also known as a humidistat) from your local hardware store. They’re not expensive and will let you know the humidity level accurately.

Does a Furnace Humidifier Cause Mold?

The short answer is no – if you take the basic steps to prevent it.

Mold spores are naturally everywhere – they’re just a natural part of our environment. Mold needs two things to grow: water and oxygen. But they don’t need light.

Mold can thrive in any damp area inside a home, often in bathrooms or near plumbing leaks. Furnace humidifiers do not cause mold unless they are set much too high, creating the conditions needed to help mold take over. Again, keeping your humidifier set to 45% should work, but don’t forget to keep checking your hygrometer to ensure you’re getting the right results.

Here are some other important steps to keeping mold in check in your home:

  • Ensure your bathroom has a ventilation fan that works. The humidity from an entire family taking long hot showers can help contribute to mold growth in the bathroom.
  • If you cook a lot using boiling water, you may want to turn your humidifier off for a while, and ensure you have a range hood that vents to the outdoors.
  • If your technician suspects you might develop mold in your ductwork, a UV purification system will help eliminate the problem. Getting your ductwork cleaned and sprayed can help.
  • Front loading washing machines can develop mold if they’re not cleaned out periodically.

Watch for Temperature Drops

The amount of moisture that your home’s air can hold varies with the temperature. Warmer air can hold more moisture than cold air, so if the temperature drops the water can form condensation if it’s too humid. For this reason, try to keep a nice consistent temperature throughout the home, and get your family to agree on a sensible temperature range.

If there’s a sudden cold snap, it can mean your windows get colder than ever, and frost can form. When it melts, it can drip down and pool in the walls if there are leaks around the window. Check the seal around your windows, and if caulking is worn replace it.

Should I Maintenance My Furnace Humidifier?

Whole home humidifiers work best with modern variable-speed furnaces. That’s because these operate at lower, efficient speeds most of the time and can provide a more continuous flow of moistened air to your home. It’s also good to know that variable-speed furnaces are much more energy efficient and less maintenance.

Having a qualified technician assess your home is the smartest things you can do to ensure you stay warm and healthy all winter long.

Best Furnace Humidifier Brands

1. GeneralAire Furnace Humidifiers

GeneralAire is a well-respected brand in the heating and cooling industry, known for producing high-quality products that are built to last.

Their furnace humidifiers are no exception, with many customers noting their durability and effectiveness in maintaining proper humidity levels in their homes.

In addition, the company offers excellent customer service and a strong warranty, which further instills trust in their products.

2. Aprilaire Furnace Humidifiers

The Aprilaire brand is the best option for installing a furnace humidifier due to its high quality and durability.

Aprilaire has been in business for over 70 years and has a reputation for producing reliable and efficient products.

Their humidifiers are designed to work seamlessly with your furnace, making it easy to install and maintain. Additionally, Aprilaire offers a variety of humidifiers to choose from, allowing you to find the best option for your specific needs and budget.

Want to Know More?

There are actually several different types of furnace humidifiers, and the right one will depend on your needs, the size of your home and your budget. You can learn about the different types of air filtration systems and whole-home humidifiers and dehumidifiers.



Save up to $7,100 with the Greener Homes Grant and exclusive Dr HVAC rebates on heat pump systems!