How to Change your Whole House Humidifier Filter

How to Change the Filter in a Whole House Furnace-Mount Humidifier

Whole house humidifiers help maintain comfortable humidity levels during the dry months—but only if their filters (also called water panels, evaporator pads, or humidifier pads) are clean and functioning properly. Replacing this filter regularly helps ensure optimal performance and prevents mineral buildup.

Here’s a general guide for changing the filter in most furnace-mounted humidifiers:

Step 1: Turn Off the Power to the Furnace

For safety, switch off your furnace at the thermostat or the breaker panel before working on the humidifier.

Step 2: Locate the Humidifier Panel

The humidifier is typically mounted on the side of your furnace or air handler. Look for a removable cover or panel—this may be held in place with screws, clips, or tabs.

Step 3: Open the Humidifier Housing

Remove the front panel or access door to reveal the internal components. Inside, you’ll see the humidifier filter (usually a rectangular, mesh-like pad enclosed in a plastic frame).

Step 4: Remove the Old Filter

Carefully slide out the old filter or water panel. Some models may have a metal tray or frame that holds the pad in place—note how it fits so you can reassemble it correctly. Dispose of the used filter properly.

Step 5: Install the New Filter

Insert the new filter in the same orientation as the old one. Many filters are directional—check for arrows or labels indicating “up” or “airflow.”

Step 6: Reassemble the Unit

Replace the frame or tray if necessary, then secure the cover or panel back onto the humidifier housing.

Step 7: Restore Power to the Furnace

Turn the furnace back on at the thermostat or breaker. If your humidifier has a seasonal setting or control panel, check that it’s properly configured.