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How to Maintain your Humidifier

It’s the cold season once again, and if you have a humidifier at home, chances are it’s getting a heavy workout. Not only are more people staying indoors due to the coronavirus pandemic, but you will likely be cooped up thanks to this winter being one of the coldest in years.

All of which underscores the importance of having a well-maintained humidifier. So here are tips to make sure your humidifier is fully up and functioning throughout the winter.

Why It’s Important to Clean your Humidifier

Just like your HVAC and air purifier, humidifiers can build up a lot of household pollutants in the course of improving your home’s air quality. These particles include:

  • Minerals from the hard water used
  • Bacteria in the filters
  • Mold spores
  • Household chemicals in the tank or impeller
  • Dust and dirt in the grills and fan

These minute particles can have health implications if left in your humidifier. They can also cause the unit to perform poorly and have a shorter lifespan.

Which Type of Humidifier Do You Have?

Humidifiers come in different versions and sizes. They also use different technologies to generate moisture. 

The first step is to identify which type of humidifier you have.

Types of Humidifiers

Steam humidifier

Also known as vaporizers, these are portable units that boil water to produce steam, and commonly sit on tabletops.


These generate humidity by blowing air through a moistened filter. They can be identified by the fan used to disperse the moisture, as well as the air cleaner-type filters they have inside.

Impeller humidifier

Also known as mist humidifiers, these use a fast-rotating disk or diffuser to cool the air. 

Ultrasonic humidifier

As their name suggests, these use ultrasonic vibrations to excite the stored water, turning it into fine droplets that are then blown out by a fan. Some models can switch between warm and cool mist to match the season.

Central or whole house humidifiers

Central or whole house humidifiers are built directly into the house HVAC, and thus service the entire home. They are the most expensive kind, but are also the most efficient.

Humidifier Maintenance by Type

Steam Humidifiers/ Vaporizers

  • Unplug the humidifier and remove the tank.
  • To clean the tank, pour 1-2 cups of undiluted white vinegar. Some manufacturers may recommend diluting the vinegar with water, so check your owner’s manual.
  • Do NOT drain the vinegar. Instead, place the tank back on the base.
  • Allow it to drain into the unit’s reservoir. This will clean it out while loosening any mineral buildups.
  • Allow the vinegar to stand for 15-20 minutes.
  • Empty the unit, then use a small brush or scrub to clean out the interior of declogged minerals and sediment.
  • Rinse thoroughly with water.
  • Allow to air dry for at least 30 minutes before reassembling.

Note that vaporizers use hot water to create steam. Before cleaning, allow ample time for the unit to cool down to avoid burns or scalding.

Evaporative humidifier


  • Unplug the unit and remove the tank.
  • Pour a cup or 2 of white vinegar into the tan. Check the manual if the vinegar should be poured straight or diluted with water.
  • Let the vinegar soak in for at least 20 minutes to soften up limescale deposits.
  • Empty the vinegar, then scrub out the interior with a sponge or brush.


  • Soak the wick in clean for 20 minutes.
  • Occasionally swish it around to dislodge encrusted minerals.
  • Avoid using bleach or detergent on the wick, as they can remove any antimicrobial finish.
  • To prolong the wick’s life, turn it over whenever you refill the tank. This keeps it from drying out, and allows it to age evenly.

Note that wicks are designed to be consumable. Depending on your humidifier usage and water hardness, they may need to be replaced every month or two. When in doubt, replace the wick instead of cleaning it.


  • Wipe down the grill with alcohol or mild disinfectant.
  • If the fan is accessible, gently wipe the blades with a damp paper towel to remove accumulated dust.
  • Make sure the blades rotate freely before reassembling.

Impeller Humidifiers

  • Unplug the humidifier and remove the tank.
  • Pour 1-2 cups of white vinegar into the tank (check the manual if it should be straight or diluted with water).
  • Place the tank back into the base, and allow it to sit for 15-20 minutes to dislodge limescale buildup.
  • Empty the tank, then use a small brush or scrub to clean out the interior.
  • Rinse thoroughly with water.
  • Allow to air dry for at least 30 minutes before reassembling.

Note that impeller humidifiers are susceptible to “white dust”, caused by the minerals in tap water. To lessen white dust, the EPA recommends using water with low mineral content such as distilled or purified water.

Ultrasonic humidifiers

Small parts

  • Unplug the unit and remove the mist nozzle.
  • Rinse the nozzle with clean water and set aside to dry.
  • Wipe the outside of the unit with a clean dry cloth. Avoid using liquids around delicate parts such as water sensor or nebulizer.


  • Empty out the tank, and fill with 1-2 cups of white vinegar. Check the manual if it should be poured straight or diluted with water.
  • Put the tank back in the reservoir and allow to sit for 20 minutes
  • Empty the vinegar, and use a sponge or brush to scrub out the interior.
  • Rinse with clean water and allow to air dry.

As with impeller humidifiers, ultrasonic humidifiers can leave a white dust residue when used with hard or mineral water. As such, the EPA recommends using distilled or purified water for these types of humidifiers.

Whole house humidifiers

The good news about central humidifiers is that they have longer maintenance intervals compared to tabletop or portable units.

Steam Humidifier

  • Turn off the humidistat to prevent the unit from entering a heat cycle during maintenance.
  • Drain the water following your owner’s manual.
  • Allow ample time for the whole system to cool.
  • Remove the lid.
  • Take out the overflow pan.
  • Remove the main drain tube, and check for signs of clogging or buildup.
  • Remove the overflow tank and use a 1:3 water-vinegar solution to descale.
  • Use the same solution to clean the metal water discharge and water supply tubes.
  • Replace the water filter as needed according to the maintenance schedule.
  • Check the O-rings for cracks or deformation before reassembling.

Reservoir / Drum Humidifier

  • Remove the humidifier cover and drum.
  • Take out the foam pad from the drum shaft, by either removing the clips or assembling the two halves of the drum.
  • Use a 1:3 water-vinegar solution to clean the foam pad. Alternatively, you can use a commercial calcium remover solution.
  • Rinse the pad with clean water.
  • If the pad is damaged or ripped, replace it with a new one.
  • Reassemble the drum, but leave the cover off.
  • Fill with water until the water supply is cut off the float assembly.
  • The drum should dip into the water reservoir and fully wet. If not, adjust the float arm using the adjusting screw on the float lever arm.
  • Replace the humidifier cover.

Flow-through / Drip Humidifier

  • Detach the clips that hold the inlet feed tube and distribution manifold on top of the humidifier.
  • Remove the manifold from the evaporative screen pad and manifold housing.
  • Use a 1:3 water-vinegar solution to clean the evaporator screen pad, or a commercial limescale dissolver.
  • Soak the pad until the mineral crust dissolves, then rinse with water.
  • Repeat as necessary until all buildup is removed.
  • Test the humidistat and solenoid valve. When the furnace is running, the valve should open and water should appear in the inlet tube.
  • If the water doesn’t flow, check the humidistat with a multimeter or voltmeter. Check for 24v in the solenoid terminals, fill valves and wires. No volts means it’s time to replace it.
  • If the humidistat works but water doesn’t flow from the solenoid valve, then it’s the valve that needs to be replaced.

How Often Should You Clean Your Humidifier?

According to the EPA:

Portable humidifiers – every 3 days to once a week

Console humidifiers – once a month

Central / whole home humidifiers – every 2-3 months

Note that these figures can vary depending on your humidifier usage, water hardness and other variables such as the season and local climate conditions.

Mickey Luongo

Mickey is the resident heating and air conditioning expert with over 15 years of experience in the industry.

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