Do You Really Need a Furnace Humidifier?

Updated April 16, 2020

Humidifiers are a common appliance to keep homes comfortable, especially in winter when the air can be very dry. Portable humidifiers run in specific areas of the home, such as bedrooms, while furnace humidifiers are installed with the HVAC system to distribute moisture throughout the house. Whether you need one depends on the conditions of your home and your personal preferences. This article will discuss the specifics of furnace humidifiers, how they work and what they can do for you and your home. Woman relaxing comfortably in clean, modern home

Woman relaxing comfortably in clean, modern home

fizkes / Shutterstock

What is a furnace humidifier?

Also called whole-house humidifiers, furnace humidifiers connect with forced-air HVAC systems to moisten the warm air that the furnace is pushing throughout the home. They work by holding a reservoir of water, by using a fresh water supply or by creating steam to add to the airflow from the furnace. Here are the various types of furnace humidifiers available:

Bypass humidifiers

Bypass humidifiers have a water panel. With no motors of their own, they rely on air from the furnace’s blower to pick up moisture as it passes over the water panel before circulating through the ductwork. They’re only active, therefore, when the furnace runs. There are pros and cons to this type of system. The pros include low energy usage, less chance of breaking down (because there are fewer moving parts) and less chance of mold since moisture is only pushed through the ducts when warm air is moving through with it. The one downside is that it's less effective at humidifying the air in your home compared with some other systems because, after the air picks up moisture from the panel, it's rerouted back to the furnace before being distributed throughout the home. During this process, the air loses some of its moisture. The required bypass ducts also take up extra space for installation.

Flow-through units

Flow-through units, by contrast, have their own fans. As air passes through the furnace’s air supply, it is blown over the water panel to pick up air. It can moisten and distribute air even when the furnace blower isn’t operating.

Steam humidifiers

Steam humidifiers boil water to create steam that is then distributed along with air from the furnace. Steam is very effective at adding moisture to the air in your home, however, steam furnaces cost more money to buy and operate. Whole-home humidifiers are governed by built-in humidistats, which measure the humidity of the air and only allow the system to work when the humidity dips below its set point. This minimizes the risk of over-humidifying the home, which can lead to mold, condensation on windows and walls and a hot, sticky feeling for the building's occupants.

Benefits of a furnace humidifier

Why would you need a humidifier on furnace setup in the first place? There are some great health, comfort and home benefits that come with moist air. Ideal moisture levels sit between 30%-40% humidity, but some areas of the country can be extremely dry in the winter, reaching below the 20% range in a heated home. This dryness can contribute to dry skin, chapped lips and possibly nose bleeds. Dry air can also trigger sinusitis or asthma flare-ups. Your home reacts to dry air, too. You might see more static electricity, peeling wallpaper and cracking furniture from very dry air. Wood floors in particular can shrink or even crack, causing unsightly gaps between boards. Regulating humidity levels will keep the wood from shrinking and your floors looking smooth. Adding a furnace humidifier can also lead to less overall energy usage in the home because the furnace may not need to work as hard. Keeping the air moist can make the home feel relatively warmer and you’ll be less likely to crank the heat. Personal or portable humidifiers are always an option. They're relatively inexpensive and can operate in individual rooms. But these units suffer some downsides. They need to be filled daily and turned back on to operate, so they're not offering a constant climate of moist air. Portable humidifiers are also more labor-intensive to run on a daily basis. They need to be cleaned thoroughly and often to keep scale to a minimum. There are some concerns that bacteria and mold growing inside poorly-cared-for portable humidifiers can be distributed with the moisture, wreaking havoc with air quality and personal health. Whole-home humidifiers installed on the furnace are the best way to get consistent humidity with less fuss. Because they’re installed directly on your furnace and work with your HVAC system, they work constantly with little extra thought required, outside of regular maintenance and keeping an eye on your humidity levels.

Do you need a furnace humidifier?

A furnace humidifier is not an absolute necessity for your home like a heating system is in cooler climates, but there are some specific reasons you might consider a humidifier on furnace solution.

Health reasons for a furnace humidifier

The first reason you might need a furnace humidifier is if you're experiencing health problems from overly dry air. A furnace humidifier can provide relief from dry, cracked skin or asthma symptoms caused by dry air. For some people, these may seem like minor winter nuisances, but for others, they can impact sleep, health and quality of life. If you are suffering because of the conditions in your home, low humidity levels may be to blame.

Climate conditions

Your outdoor climate may make a furnace humidifier a good idea. Dry air conditions are generally worse in cold-weather regions, because colder air tends to have lower humidity. Areas of the country that get especially low temperatures will be most susceptible to problems stemming from dry air. To make matters worse, running the furnace on those bone-chilling days further dries out your air. This can be exacerbated in older homes, which can be less air-tight and less efficient. In those homes, more cold air will enter, and your furnace may be running even more of the time. In smaller homes or apartments, portable or room-specific humidity solutions that may suffice. If you think you may benefit from installing a furnace humidifier, contact your local HVAC pro for more information.

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