Dehumidifier Maintenance: How to Clean the Filter, Coils, Pump and Drain Line

How we made this guide: picks, prices and specs come from our catalog and the makers' published specs, owner quotes come from customer reviews on our product pages and every guide is checked and edited by Trevor Hall.

Dehumidifier maintenance comes down to four jobs: clean or replace the air filter on the maker's schedule (check it every few weeks in heavy use), keep the coils and drain pan clean, flush the condensate pump and hose and check the drain line before each season. Plan on about 30 minutes, a vacuum with a soft brush attachment, a bucket and a little mild detergent. The filter and hose work is easy; anything inside the refrigerant circuit is a job for a qualified service person.

Most pages on this topic cover a home unit in a basement. This one covers commercial machines and uses the makers' own manuals for four units we carry: the AlorAir Sentinel HDi90 Duct-able, the Ebac WM80-D, the XPOWER XD-125 and the Ebac DD200 desiccant. Anything we add beyond the manuals is labeled "typical" and is a rule of thumb, not a maker's figure.

The maintenance checklist

Print this table and tape it inside the van. Intervals marked "typical" are ours; where a maker gives a schedule, the table says so.

Tools and supplies

• Shop vacuum with a soft brush and a crevice nozzle
• Compressed air with a blow nozzle, for coils and filters
• Bucket, warm water and a mild detergent
• Soft brush, lint-free cloths and a screwdriver for the top cover
• A replacement MERV-8 filter if you run the HDi90

Step 1: Clean or replace the air filter

XPOWER's manual puts it directly: the performance of the dehumidifier will be greatly reduced if the filters become blocked.

1. Switch the unit off and unplug it.
2. Slide or lift the filter out as shown in your manual.
3. Vacuum the loose debris with a hose and nozzle. This is XPOWER's step for the XD-125.
4. Wash in warm water with a mild detergent and let it air dry. XPOWER says to reinstall only when it is fully dry.
5. Refit it. Ebac's WM80-D manual lists the same options for its filter: compressed air, a vacuum or a wash in warm water.

The WM80-D carries a washable slide-out filter. The HDi90 Duct-able carries a pre-filter and a MERV-8 filter at its round intake end. Typical practice, not an AlorAir schedule: vacuum the pre-filter at each check and replace the MERV-8 when it is visibly loaded. AlorAir sells replacement MERV-8 filters for the HDi90 series and publishes a short video on changing one on the standard Sentinel HDi90 and HD90. On the Duct-able Version the filters sit in the round intake end, so the access differs.

Step 2: Clean the coils

Ebac's routine service steps for the WM80-D say to clean the surface of the evaporator and condenser coils by blowing the dirt out from behind the fins with compressed air, holding the nozzle away from the coil to avoid damaging the fins. Vacuuming the coils is the listed alternative.

• Remove the top cover only with the unit unplugged, and work gently.
• Never steam clean the coils or put direct heat on an iced coil, per Ebac.

AlorAir shows the coil clean on the standard Sentinel HDi90, which shares its cabinet with the Duct-able Version:

The same Ebac manual describes a refrigerant check. After 15 minutes of running, the evaporator coil should be evenly frosted across its surface, or covered in water droplets instead of frost above 77°F (25°C). Partial frosting together with frost on the thin capillary tubes points to lost or low refrigerant. That is a job for a qualified service person, not the shop floor.

Step 3: Flush the pump and check the drain line

Three of the four units here move water without a bucket: the HDi90 Duct-able (built-in pump, manual drain button, 19.6 ft hose), the WM80-D (internal pump, 25.5 ft hose) and the XD-125 (automatic purge pump, 20 ft hose).

The XPOWER manual says to uncoil the entire drainage hose on the rear of the unit, place the open end in a drain, bucket or outdoors. The hose must not be restricted or kinked. It also says to press Purge to empty the pump reservoir, and to always purge before moving the machine to avoid spillage. The pump purges by itself for 40 seconds after the unit turns off.

Typical flush routine, after a dirty-water job or before storage:

1. With the unit off and unplugged and the cover off, wipe out the drain tray and clear any slime from its outlet with a soft brush and a little mild detergent. Then pour a cup or two of clean water slowly into the tray or pump reservoir, never enough to overflow it, plug in and let the pump clear it. Repeat until the water runs clear.
2. Press the manual drain or purge button and watch the water leave the hose.
3. Walk the hose end to end. Straighten kinks and look for a section that sags and holds water.
4. Match the hose height to the machine. On the WM80-D, Ebac's troubleshooting table lists a drain pipe set too high as a cause of water flooding inside the machine and says to ensure that no section of the drain hose is above the level of the water outlet. On the XD-125 the purge pump can lift the water, but XPOWER says not to raise the hose more than 15 ft above the unit.

Step 4: Wipe the housing and check the cord

Wipe the outside with a damp cloth. XPOWER says not to clean the appliance with organic solvent, and the XD-125 body is roto-molded polyethylene, which wipes clean. Look at the cord and plug for cuts. XPOWER says not to obstruct the air inlets, outlets or drainage hose.

Desiccant dehumidifier care

A desiccant unit like the DD200 has no coils or drain line to clean; its wet-air exhaust duct takes the drain line's place. Ebac says the wet air must be ducted outside the room being dried, with the duct as short as possible and sloped down away from the unit so condensed water cannot flow back into it. Check that slope at every setup. The unit dries air by passing it through a slowly rotating silica gel rotor, and the filter protects that rotor. Ebac says to check the filter at least once a month and never to run the unit without its filters, because dust can damage the rotor.

The same manual calls the rotor and the PTC heaters maintenance free. If the rotor needs cleaning, Ebac says to blow dirt from it carefully with compressed air and keep the unit dry. Browse our desiccant dehumidifiers if your job is cold or low-humidity drying.

Crawl space and restoration units

A crawl space dehumidifier often works in dust, so it gets the heaviest filter schedule. Typical advice: check the filter every few weeks in its first season, then set the interval by how loaded it looks. If yours is ducted, like the HDi90, also check the duct joints and flex for kinks. See our crawl space dehumidifiers for the full range.

Restoration units collect drywall dust, sawdust and soot, so check the filter between jobs, not between seasons. For larger or fixed sites, see our industrial dehumidifiers.

Storing and moving between jobs

• Purge or drain first. The XPOWER manual says to always purge the XD-125 before moving it, to wait at least three minutes after turning it off before moving it, and to wait 30 minutes after transporting it to a job site before switching it on so the refrigerant system can stabilize.
• Let the filter dry fully, coil the hose loosely and store the unit upright and dry.

Common mistakes

• Refitting a damp filter. XPOWER says to reinstall it only when it is fully dry.
• Running the DD200 without its filter. Ebac says dust can damage the rotor.
• Steam cleaning the coils or putting direct heat on an iced coil. Ebac warns against both.
• Switching the XD-125 off by pulling the plug. XPOWER says to use the power button.
• Moving an XD-125 without purging it first, or cleaning its housing with organic solvent.

When to replace instead of repair

• The compressor runs, but after 15 minutes the evaporator coil is only partly frosted and the thin capillary tubes are frosted too. Ebac says that points to lost or low refrigerant, a job for a qualified service person.
• Repair quotes approach the price of a new unit. Price a new commercial dehumidifier of the same class before you pay for a long repair; small 35-pint units in our range start under $500.
• The unit no longer holds its setpoint after a clean filter, clean coils and a clear drain line.

Warranties can matter here. The HDi90 carries a 12-month limited warranty from the date of delivery. The WM80-D lists a 1-year unconditional warranty and a 3-year warranty on the compressor, condenser and evaporator. The XD-125 and DD200 list 1-year limited. XPOWER also notes that the power cord and filters are not covered. Its warranty excludes unauthorized repairs, so keep your own work to the filter, hose and housing.

For how each type dries air, and why the care differs, read How does a dehumidifier work?

Frequently asked questions

How often should I clean a dehumidifier?

Follow your maker's schedule first. Ebac asks for a filter check at least once a month on the DD200. As a typical rule, check the filter every few weeks in heavy use and clean the coils once a season.

What is the best way to clean a dehumidifier?

Unplug it, vacuum the filter, wash it in warm water with mild detergent, let it dry and refit it. Then blow or vacuum the coils and flush the pump and hose. The filter steps are XPOWER's, the coil steps are Ebac's and the pump flush is our typical routine.

Should I run my dehumidifier constantly?

You can run it continuously if the job calls for it. The HDi90 Duct-able has a continuous mode and the XD-125 runs continuously when set below 26%. Otherwise set a target humidity and let it cycle.

Can I throw an old dehumidifier in the garbage?

Not as is. A refrigerant dehumidifier holds refrigerant (a desiccant unit like the DD200 does not), and EPA rules under Section 608 of the Clean Air Act do not allow it to be vented. Ask your local recycler or waste authority how they handle it.

Is it normal for the pump to purge after I switch the unit off?

On the XD-125, yes. XPOWER's manual says the pump automatically purges for 40 seconds after turning the unit off.

Can you run vinegar through a dehumidifier to clean it?

None of the four manuals here mentions vinegar. XPOWER says to wash the filter in warm water with a mild detergent and not to clean the appliance with organic solvent, and Ebac says to keep the DD200 dry, so stick to those.

What is the most common dehumidifier problem?

Low water collection. XPOWER's troubleshooting table blames a blocked filter, a blocked condensation hose, low room temperature or too little running time, and Ebac lists dirty coils or filters for poor airflow. Clean those first, then call a service person.

Related guides

• Dehumidifier Not Collecting Water? Causes and Fixes (Including Frozen Coils)
• How Does a Dehumidifier Work? Refrigerant, LGR and Desiccant Explained
• What Size Dehumidifier Do I Need? Pints per Day, AHAM vs Saturation and a Sizing Chart
• How Much Does It Cost to Run a Dehumidifier? Watts, Hours and Cost per Day