man relaxing on couch enjoying whole house humidifier

Installation of a whole house humidifier is one of the simplest ways to maintain proper humidity levels in your home. A comfortable home environment is partly derived from an appropriate humidity level. More importantly, managing the humidity level in your home is conducive to your family’s health. According to Cleveland Clinic, maintaining proper humidity levels reduces allergens, asthma triggers, and infection-causing airborne contaminants, such as bacteria, viruses, and dust mites.

Whether you add a whole-house humidifier to your heating system or set up a self-contained unit in your home, your household will benefit from the many advantages humidifiers offer.

What Is a Furnace Humidifier?

A furnace humidifier is a small appliance that connects to the HVAC system’s ductwork near the furnace. Most of these humidifiers operate while the furnace runs, but some can work independently. The humidifier injects water vapor into the air flowing through the ductwork to raise humidity levels.

Furnace humidifiers are connected to the home’s water supply line, so there are no basins or tanks to fill. The home’s humidity level can be adjusted by setting the humidistat. According to the Consumer Product Safety Commission, the ideal relative humidity for residences is between 30 and 50%.

furnace humidifier works illustration

Types of Whole House Humidifiers

Evaporative and steam humidifiers are furnace humidifiers that connect to the home’s ductwork and function as HVAC system components.. Evaporative humidifiers are classified into two categories: bypass and powered. Self-contained humidifiers are stand-alone units that are not installed in the HVAC system.

Evaporative Humidifiers

Evaporative humidifiers use water’s natural evaporation to introduce humidity into the air. The humidifier’s water valve fills the distribution tray above the evaporative panel, and the panel soaks up the water. As the furnace’s air blows over the panel, the water evaporates into water vapor. The water vapor is sucked into the furnace’s fan or blown into the ductwork by the humidifier’s fan and distributed to the house through the heating vents. Unused water empties out of the humidifier into a floor drain.

Most evaporative humidifiers turn on when the gas furnace or heat pump runs, and the humidistat senses the relative humidity below the setting. Some humidifiers can run independently of the heating system, but a hot water supply is needed in addition to the cold water supply.

Two types of evaporative humidifiers are bypass and powered humidifiers.

Bypass humidifiers

Bypass humidifiers require the installation of a bypass duct to divert air from the HVAC system to the humidifier. The humidifier can be installed on the main stack of the return duct or the supply duct. The bypass duct diverts air flowing through the ducts to the humidifier, which gathers moisture. The humidified air is then sucked back into ductwork by the furnace fan and distributed to the house.

Powered humidifiers

Powered humidifiers have a power supply and fan to pull air into the unit to be humidified and to distribute the moist air to the ductwork. These humidifiers do not require a separate bypass duct, which provides easier installation and less maintenance. Another advantage of powered humidifiers is the ability to produce more humidity than bypass humidifiers.

Steam Humidifiers

Steam humidifiers produce steam instead of water vapor to humidify the air. The humidifier boils water by applying an electrical current to two electrodes submerged in a water canister. A dispersion tube sends steam from the boiling process into the ductwork.

A steam humidifier can work independently of the furnace with the blower fan running because it has its own power supply. Steam humidifiers perform better than evaporative humidifiers but have higher upfront costs and operating expenses.

Self-Contained Humidifiers

A self-contained humidifier is an excellent option for a house lacking ductwork. Sometimes referred to as a pedestal or portable humidifier, these free-standing units operate independently of any HVAC system. The humidifier contains a water tank that must be filled with water, and a fan circulates humidified air. Self-contained humidifiers require more attention and maintenance than ducted humidifiers; the tank must constantly be refilled and cleaned.

What Are the Pros of a Whole House Humidifier?

Whole-house humidifiers offer the benefits of automatic humidity control, low maintenance, and improved indoor air quality.

  • Automatic Humidity Control - Set the humidistat at the desired humidity level, for example, 40%, and the humidifier will add moisture to the air until it reaches the setting.

  • Low Maintenance - The evaporative panel should be replaced once or twice a year, and occasional wipe-downs of the unit and removal of mineral deposits are recommended. On the other hand, self-contained humidifiers require ongoing maintenance, including cleanings every two weeks, adding an antimicrobial agent to the water basin, and regularly refilling the basin.

  • Indoor Air Quality - Humidifiers improve indoor air quality. Humidified air is beneficial for respiratory and immune system health. According to Mayo Clinic, humidifiers can reduce health issues caused by dry air, such as bloody noses, cracked skin, and dry sinuses, and reduce the symptoms of colds and other respiratory illnesses. According to Yale University researchers, dry air not only increases the transmission of the flu virus, but it may also reduce the body’s immune system response to viruses.

What Are the Cons of a Whole House Humidifier?

Whole-house humidifiers have some drawbacks, including installation requirements, expenses, mold, and mildew growth.

  • Installation - Self-contained humidifiers are quick and easy to set up, but ducted humidifiers require costly professional installation.

  • Expense - Whole-house humidifiers are significantly more expensive than portable units. Whole-house humidifiers range from $150 to $800, with steam humidifiers at the upper end of the range—factor in another $250 to $500 for installation fees.

  • Mold and Mildew Growth - Mold and mildew can grow in the moist environment of the HVAC system and a self-contained unit if the humidifier and HVAC system are not properly maintained.

Affordable Furnace Humidifiers

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Clean Comfort 17 GPD Humidifier with Auto Thermostat

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Clean Comfort 18 GPD Humidifier with Manual Thermostat

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Clean Comfort 18 GPD Humidifier with Auto Thermostat

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A whole-house humidifier combats dry, uncomfortable indoor air and improves air quality. Proper humidity levels are also essential for your family’s comfort and health.

Ducted humidifiers work with your forced air heating system to introduce moisture to your home’s air. The best part is that they require very little from the homeowner after installation. The humidistat automatically controls the home’s humidity level, and maintenance consists of little more than periodic evaporator panel changes. Self-contained units require much more ongoing maintenance, but they are suitable for houses without ductwork. Overall, the advantages of a whole-house humidifier outweigh the disadvantages.

Frequently Asked Questions

Where does whole house humidifier go?

Whole-house humidifiers are installed on the HVAC system’s supply or return plenum near the furnace. Configurations vary and are determined by the humidifier’s type.

When to use whole house humidifier?

Whole-house humidifiers should be used when running the heating system to add moisture to the dry air. Humidifiers are not needed during warm weather because the air tends to be more humid.

Does whole house humidifier cause mold?

Correctly set and maintained whole-house humidifiers do not cause mold. Mold growth results from excessive humidity and a lack of HVAC system maintenance. Condensation on the windows, dust, dirt inside the HVAC system, and dirty evaporator panels foster mold growth.

Are whole house humidifiers worth it?

Whole-house humidifiers are an added expense, but they are an effective and effortless way to create a more comfortable and healthy environment. If you are suffering from dry indoor air or fed up with the demands of a portable humidifier, a whole-house humidifier might be worth it.

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