How Does A Furnace Humidifier Work And How Much Does It Cost?

Kenneth Wilson

One foolproof way to entirely change the humidity level of the entire home is to install a furnace humidifier– not a tiny tabletop humidifier or a freestanding unit. On average, unit and installation costs run from $200 to $2,200.

It is considered an essential component in every home, especially during the winter months and the notoriously dry winter air. But, several homeowners are still clueless as to how a furnace humidifier works– so we’ve prepared this informative article for you to understand the system behind it.

Why is Dry Winter Air an Issue?

It’s common for some people to deal with dry skin, hands, and scalp in the winter. There are also people suffering from sore throats and cold-like symptoms. Others note that their asthma and allergies were triggered. And in some cases, nosebleeds may occur.

This is where a furnace humidifier proves to be a crucial addition to your home. It protects you and your family, along with the structures inside your home.

Does a Humidifier Work on a Furnace?

Simply put, ensuring proper humidification can not only protect your home but will also make you feel more comfortable at a lower thermostat temperature. This saves both energy and money in turn.

That said, furnace humidifiers can add moisture to the air distributed by the furnace using evaporation. It is usually mounted to the furnace’s hot air supply, connected to a water source and the ductwork.

Humidifiers can work with standard furnaces with the help of these common parts:

  • Water Collector It can either be an evaporator pad or a reservoir
  • Water Control Valve Is a float or a solenoid used as a humidifier water dispenser to reach the target humidity level
  • Blower Produces the necessary air movement for evaporation
  • Humidistat Provides easy control of the humidity levels and allows you to turn the humidifier ON/OFF

Furnace Humidifier Average Costs

On average, furnace humidifiers cost anywhere between $120 to $1,350 for the unit alone. Installation costs will hike up prices to $200 to $2,200. The total price may vary depending on the humidifier type and additional features.

Furnace Humidifier System Type

Average Costs (Unit Only)

Total Costs (Including Installation)

Drum Humidifier

$120 - $300

$250 - $800

Flow-Through Humidifier

$120 - $500

$250 - $1,000

Steam Humidifier

$320 - $1,350

$500 - $2,300

Spray-Mist Humidifier

$120 - $170

$120 - $170 (DIY)

First, we have flow-through humidifiers, which start from $120 to $500 for the unit only. With installation, the total costs may add up to $250 to $1,000. Keep in mind that this is the most standard humidifier type for most homes in the country.

Next, we have drum humidifiers which cost $250 to $800 with installation or around $120 to $300 for the unit alone. Although drum models have a relatively easy installation process, they are more prone to mineral or mildew buildup from stagnant water. As such, they can be high maintenance.

Another humidifier type is steam models, costing $500 to $2,300 installed or $320 to $1,350 for the unit alone. These units are usually mounted on the wall and work independently from the home’s heating system.

Important Note: steam humidifiers are considered the cleanest or most hygienic choice as hot water creates steam to kill germs.

Lastly, we have spray-mist humidifier units, which only cost $120 to $170 as these units usually have a DIY installation. They work by releasing mist through a fine nozzle into the HVAC ductwork.


If your home uses well or hard water, you may need to install a water filter and softener to prevent clogging problems. Doing so will also avoid mineral build-up in the spray nozzle. On average, water softener installation runs for $820 to $2,500.

How Do Furnace Humidifiers Work?

True to its name, furnace humidifiers are usually installed into your HVAC, where the ductwork leads out from the furnace. Once warm air leaves the furnace, it passes through the fan and the ducts before flowing into the humidifier. The humidifier-produced moisture is infused with the heated air from the furnace. (Related: Are Aprilaire Humidifiers Worth It? (Reviews & Buying Guide))

Ultimately, the air will then be dispersed throughout the home. There are three primary types of furnace humidifier systems, each having a distinct method.

  • Steam humidifier This furnace humidifier type produces both cool and warm air, giving off the highest moisture level. Steam humidifiers have relatively easy maintenance, but it requires electricity to power. You can count on this humidifier type to self-generate steam, boil water on-demand, and inject the steam into the furnace’s heated air.
  • Flow-through humidifiers This works by exposing the warm air produced by the furnace to a trickle of water. As a result, the water evaporates into thin air as it leaves the furnace. You will need to change the humidifier filter pad for this one periodically, but the upkeep is considered low maintenance.
  • Drum humidifiers Are composed of a pan of water and a rotating belt passing through it. As the water from the belt evaporates, it leaves the furnace accordingly. Given that drum humidifiers have a standing pan of water– you must clean it frequently to avoid possible mold growth.

Keep in mind that you are free to install a humidifier on virtually any furnace system type, including old ones. You can engage the humidifier if the system is in heat mode by adjusting the humidistat dial settings. Wait until you hear a click to determine the humidity levels in your home at present before adjusting the setting accordingly.

Now, if the heating system comes with a bypass damper, ensure it is in an open/winter position parallel to the duct. Once you see water draining from the humidifier as the system runs, it means it’s currently in operation.

Benefits of Furnace Humidifiers

Installing a furnace humidifier at home comes with several considerable perks. For one, you can expect no clutter in the living spaces. Furnace humidifiers can also help you save on your heating costs, as moist air typically feels warmer. As such, there’s no need to set the temperature higher.

Perhaps the most significant benefit to consider is the absence of a tank to fill, as these humidifiers are connected right to the water supply. You won’t need to struggle with the heaviness of a large tank or constantly refill a small one.

Note that furnace humidifiers ensure proper humidity levels to make your home feel warmer and more comfortable. Regardless, we strongly encourage consulting with a local technician to assess your home situation before purchasing a furnace humidifier. They can give you expert advice on the best system to keep the home comfortable.

Frequently Asked Questions (FAQs)

What’s the ideal humidity level for a home?

Overly dry air is not only hated by our bodies but also by our homes. A minimum of 35% humidity level is needed to prevent wood floors and furniture from splitting along the grains (AKA “checking”). A high level of humidity (over 55%) can increase the risk of mold growth and allow the germs to thrive, causing the wood to warp.

How can I determine dry air in my home?

There are many easy ways to determine if your home is too dry. Spotting moisture condensation on your windows or other glasswares and getting shocks from static electricity can tell that your space is too humid. If you want to be confident, purchasing a hygrometer/humidistat from your local hardware can help you. These are very affordable and will accurately show your home's humidity level.

Does a furnace humidifier encourage mold?

Even if you have a furnace humidifier, mold can still be prevented if you take the basic steps of maintaining it. Furthermore, mold spores are a natural part of the environment and will always be everywhere. Damp areas within your home are where mold can thrive, such as near the plumbing leaks and the bathroom. The furnace humidifier does not cause mold unless it is set much too high resulting in the mold taking over. Once more, ensure that your humidifier is set ideally to 45%, and do not forget to check your hygrometer to confirm that you are getting the right results.

Kenneth Wilson
February 7, 2022
Cost Guides, HVAC, Uncategorized

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done. I also operate remodeling design service for homeowners.

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