A Brief Guide to Whole House Humidifiers

Graphic of a home with a water drop to represent properly humidified home

As their name suggests, whole house humidifiers provide moisture to the air throughout your entire home. Incorporated into your HVAC system, whole house humidifiers (sometimes also referred to as fixed-installation humidifiers) can help improve everyone’s health and comfort, preserve wooden floors and furniture, reduce shocks from static electricity, and even reduce your heating bill.

Once a homeowner has decided to add a whole house humidifier, they only need to determine which type is right for their home and budget. Working directly with a professional residential HVAC installer can make this process a snap, but you’ll also likely want to do your own research first. Today’s post aims to help introduce you to your options in home humidification.

Benefits of Humidifiers

When winter comes, the air gets drier. Turning up the heat makes indoor air even drier still, which leads to dry skin and static electricity. Because pollen, pet dander, and dust can stay airborne longer in dry air, people with allergies or asthma can have a harder time breathing in winter. Also, because viruses can thrive in dry air, everyone in the home is at greater risk of coming down with the flu.

Add humidity to a home with dry air, however, and everyone will feel relief. Humidity prevents dry skin, makes breathing easier by moisturizing nasal passages, causes airborne irritants to fall to the floor out of breathing range, eliminates static electricity, and reduces the viability of viruses. Whole house humidifiers can also lead to reduced heating bills because moist air holds heat longer and better than dry air, meaning heaters don’t need to work as hard.

How Whole House Humidifiers Work:

Most people are familiar with stand-alone, portable room humidifiers that might sit on a nightstand or the floor. These provide cool or warm mist to humidify the room. Whole house humidifiers, on the other hand, can offer the same benefits, but on a larger scale.

Some whole house humidifiers are larger stand-alone units that can be set on the floor of any room. These units are not nearly as efficient as central whole house humidifiers that mount on and send moisture through the ductwork of the home’s existing HVAC system.

Central whole house humidifiers need to be connected to the existing furnace or central heating unit. They also need to be hooked up to the home’s water supply. Once installed, these humidifiers send moisture into the ducts while heating is in operation. They are typically disabled during air conditioning season when outdoor air is naturally more humid.

There are three main types of central whole house humidifiers, which may have different configurations in terms of how they work: Bypass (drum, disc wheel, biscuit-style, etc.), fan-powered, and spray mist.

The drum style bypass humidifier uses a rotating evaporator pad to carry water from the unit’s water reservoir up into the flow of the heater’s air current. “Biscuit”-style or flow-through models let the furnace blow hot air through the humidifier’s wet evaporator pad. Spray mist humidifiers propel a fine mist of water into an HVAC system’s ductwork. There are some less common types, as well, including steam humidifiers and fan-augmented flow-through configurations.

Check with your local HVAC expert to learn more about which type will work best for your system. This decision process will depend upon which dry air problems a homeowner wants to solve, your home’s physical size, what technology works with your particular equipment, and your budget.

Important Considerations

Moisture control is perhaps the most important thing to consider when shopping for a whole house humidifier. Ideal air moisture levels should be between 30 and 50 percent depending on the season and your personal comfort preferences. Keeping relative humidity (RH) in that range will provide all the benefits we’ve covered here without causing unwanted mold growth.

Homeowners should opt for only a whole house humidifier that continuously measures humidity and has both automatic and manual humidity controls. These units allow homeowners to set the desired moisture level with a humidistat as they would a thermostat. The humidifier then turns on and off as needed to maintain that level.


Each type of humidifier requires different amounts of maintenance. All types will need to have filters and evaporator pads changed at least annually. Some units will also require more frequent cleaning, like those with drum units, as their water reservoir can become stagnant.

Cost and Size

Homeowners should review the cost of annual maintenance as well as the initial cost of the unit before making a purchase. A humidifier that sells for less could end up costing more in the end if it requires frequent and expensive maintenance.

Size matters when it comes to whole house humidifiers, as well. Whole house humidifiers are rated by the square footage they can cover. Homeowners should make sure the unit they purchase can accommodate their home’s square footage. If the home has high ceilings or an open floor plan, homeowners should get a unit that can cover a little more square footage than their house’s flat footprint.

The actual size of the unit itself also matters when making a selection because it needs to fit with the HVAC system. The humidifier should be placed so that the humidity level display can be seen and accessed easily. Additionally, flow-through humidifiers require a floor drain. This may or may not exist in the area where the furnace is located.

Finally, not all HVAC systems can accommodate a central whole house humidifier. For example, central whole house humidifiers may not be compatible with electric baseboard heating systems or systems that are installed in an attic. Homeowners should check with a licensed professional before making a purchase.

Need Help Selecting the Whole House Humidifier That’s Right for You?

For more information about whole house humidifiers, or to learn which types are right for your Lancaster or Lebanon County home, Garden Spot Mechanical is here to advise. Give us a call today!