The automatic system of heating and cooling in your house hums along throughout the year without a lot of thought. Of course, you vigilantly replace that furnace filter every one to three months as your best line of defense against an overworked furnace, but did you know you might also need to clean your ductwork?
Wait, what? The ductwork? You mean that maze of metal behind the walls that carries air from one place to another inside the home? Yep, that’s the one.
Why Should I Clean My Home’s Ductwork?
Well, there are several reasons, actually. The first is that dirt and grime builds up inside the ducts as air passes through, depositing heavier particles along the sides of the metalwork.
HVAC ducts regularly collect dust, pet hair, dirt, pollen, and oils from the home. They may also collect mold and mildew.
If you’ve done any remodeling, the dust from cutting wood and sanding plaster is also moving through the system.
When insects and rodents invade the home, they may take up residence inside your ductwork too.
As the buildup affects airflow, the furnace has to work harder, causing the need for repairs and premature replacement.
Keeping your air ducts free from obstructions saves you money, both in improved energy efficiency and a delay in furnace repairs and replacement. It means less debris is pushed through to the furnace filter, which also improves efficiency and results in fewer filter changes.
Cleaner ducts also mean cleaner air, which is good for the entire family.
Plus, you might find your toddler’s lost stuffy or the pet’s favorite ball. All kinds of household items end up in the ductwork.
How Often Should I Clean the Ductwork?
Add it to the list of regular home maintenance. Plan to tackle ductwork cleaning once or twice each year, maybe with the changing seasons of fall and spring or alongside changing the batteries in your smoke detectors.
You should schedule a professional cleaning every three to five years or after any type of extensive home improvement project.
Important Note: If you become aware of rodents in the vents or mold and mildew, do not turn your HVAC system on until you’ve had a professional cleaning. The mold spores or rodent feces can cause illness when disturbed.
How Do HVAC Ducts Work?
A blower in your furnace works to force air through the ductwork and out the registers (vents) throughout the house.
A return air vent simultaneously sucks in air from the home and sends it back to the furnace. This return duct is often significantly dirtier than the supply ducts because the air hasn’t gone through any sort of filtration.
Think about the greasy air from your kitchen, the dust from the wood stove, and the pet hair flying around. All of that is sucked into the system where it is sent to the furnace where it is filtered, heated, or cooled, and sent back through the home.
Registers should be located in each room. Some rooms have more than one, and they may be located on the floor, ceiling, wall, or underneath cabinets.
Should I Clean My Own Ducts or Call the Pros?
In the long term, the answer is ‘both’. There is a lot you can do to keep your system clean and functional. Standard cleaning supplies and an afternoon of time can be enough to swab out the first several feet of ductwork behind every register in the home.
However, a professional has the ability to clean every surface throughout the system. Not only do they have longer and more efficient vacuums, but their trucks often have a holding tank for the debris that is removed.
Plus, the brushes and air whips controlled with an air compressor do a thorough job of breaking up contaminants inside the ducts.
A professional HVAC company can also send cameras down to check for damage throughout the system. Air leaks in the ductwork can cost you a lot of money, so get them repaired as soon as possible.
How Much Does It Cost to Have Ductwork Cleaned?
There are several factors involved in calculating the cost of professional ductwork cleaning. However, it typically runs between $350-$1,000. When you call for bids, make sure you’re aware of how many registers you have in the home. This is how companies typically work up a bid.
For example, if you have 21 registers at $40 each, your bill will run $840. For a home with only ten registers, you’ll be looking at $400. Charges range from $25 to $50 per vent, so you can work out a rough estimate by multiplying the number of registers by $35.
Other companies may charge by the square foot instead. This should average around $.20/square foot, so a 2,000 square foot home would again be $400.
How Do I Know When It’s Time to Clean My HVAC Ducts?
If you only use your home’s HVAC system during two seasons, clean it out about a month before you plan to kick it on each time.
On a regularly-used system, also plan for twice a year on a timeline that works for you, perhaps following heavy use in summer and winter.
In addition to preventively cleaning the ducts a few times each year, there will be other times you’ll see signs the system isn’t working at full efficiency.
For example, you may notice a musty or other odor when the air kicks on.
You may also notice dust collecting around the vents or in the space around the air filter inside the furnace.
Safety Precautions When Cleaning Air Ducts
Like other home improvement projects, there’s the potential for exposure to icky things behind the walls. Wear a mask to avoid inhaling dust, spores, and toxins. Also wear eye protection. If using a loud device, add ear protection as well.
How to Clean Ductwork DIY Style
Again, cleaning ductwork yourself won’t reach every corner of the system. In fact, it will leave many surfaces untouched. However, the more dust and debris you can remove from the ductwork, the less build-up you’ll see and the more efficiently the furnace will run, so every effort is a good effort.
Step 1 - Turn off the System
There are a few ways you can ensure the furnace isn’t blowing while you clean. The first is to simply turn the thermostat all the way down or turn it to the off position.
Another is to find the circuit breaker designated to the furnace. The furnace will be the only thing on the circuit, so flip it to the off position to cut power to the appliance.
Step 2 - Remove Vent Registers
Registers on the ground will simply need to be uncovered and pulled from the flooring. Similarly, vents located beneath cabinets are typically just set into place, so they are easy to remove.
Registers in the ceiling will be screwed into place. Remove the screws by hand or by using a power screwdriver.
Remember to also remove your return air register. This will be a larger vent, often placed near the floor or on a stairway.
Tip: If you have registers of varying sizes, label them, so you know where they go when it’s time to put them back in place.
Step 3 - Clean Vent Registers
For metal registers, soak them in a sink of soapy water and wash them with a soft-bristled scrub brush.
For wood vents, clean in the same way you clean the rest of your wood flooring.
The return air vent is large. It may need to be washed in a larger wash basin, bathtub, or outside with a hose.
Step 4 - Vacuum Ducts
Use whichever attachment does the best job with your particular vacuum. Sometimes this is a crevice attachment. Other times it might be a brush attachment or no attachment at all.
Vacuum out all the debris you can see and run the hose along all sides of the ductwork to collect dust. Use an extension to get as far into the ductwork as possible.
Step 5 - Use a Chimney Brush
The brushes from a chimney cleaner also work well on ductwork. Of course, you may not want to move directly from cleaning the chimney to the ducts since the dirt will be transferred to the ducts you are trying to clean. Either thoroughly clean the heads or use a different attachment.
Using your electric drill, attach the chimney cleaning head so you can power the rotation of the brush.
Use the flexible nylon rods to extend the brush further into the ductwork. You should be able to get at least 10 feet of distance by connecting the rods together.
Insert the end of the brush into a register opening and allow it to rotate along the sides back and forth and as deep as you can reach.
Note: Operate the drill in the regular or tightening direction. Do not rotate it in the left/loosening direction. This can cause the rods to unscrew from each other and you’ll have to retrieve your attachments from the ductwork.
Repeat the process with each register opening.
Step 6 - Examine Your Ducts
Use a quality flashlight to look inside each register opening after cleaning. In addition, to ensure the removal of debris, look for any gaps or openings where air may be able to leak out of the ductwork.
If you find any needed repairs, call in an HVAC specialist or repair the HVAC ducts yourself.
Step 7 - Vacuum Again
If the chimney sweep left behind noticeable debris, grab the household vacuum or wet/dry vac to suck it up. You want to avoid sending additional debris through the ductwork as much as possible.
In the supply air ducts, this debris will be blown into the room when the air is turned on, so remove any particles you can to avoid the mess and inconvenience.
Step 8 - Reinstall the Vent Registers
Once your registers are clean and dry, put them back into place.
Step 9 - Return Power to the HVAC System
If you previously flipped the circuit breaker or turned off the thermostat, turn it back on. Crank up the heat or drop the AC temp until the furnace kicks on. Then let it run for 15-30 minutes to blow things out of the system.
Step 10 - Replace Your Furnace Filter
At this point, your furnace filter has likely collected a lot of dust and debris. Take a look at it and replace it if necessary.
A note from the Environmental Protection Agency (EPA). In a report released in March of 2022, the EPA pointed out there is little evidence that regular dust build-up in the ductwork escapes at a level that is dangerous to human health.
Furthermore, it warns that regular ductwork cleaning is not necessary as a preventative measure.
However, it does surmise cleaning is critical if there is mold in the system, rodents are present, or ducts are clogged. It also recommends cleaning when debris is being pushed against the registers, such as when build-up occurs on your vents, or you can see particles blowing into the room.
Primarily though, the report offers advice on hiring professionals if you do decide to have the system cleaned. Use caution when hiring any professional to ensure they are licensed and bonded.
Additionally, be cautious in accepting all recommendations from HVAC cleaning companies. While some chemicals may occasionally be required (to get rid of mold for example), a regular coating of toxic chemicals is not recommended.
The EPA summarizes, saying “air duct cleaning service providers may tell you that they need to apply chemical biocide to the inside of your ducts as a means to kill bacteria (germs) and fungi (mold) and prevent future biological growth.
They may also propose the application of a "sealant" to prevent dust and dirt particles from being released into the air or to seal air leaks. You should fully understand the pros and cons of permitting the application of chemical biocides or sealants.
While the targeted use of chemical biocides and sealants may be appropriate under specific circumstances, research has not demonstrated their effectiveness in duct cleaning or their potential adverse health effects. No chemical biocides are currently registered by EPA for use in internally-insulated air duct systems.”
If you’re doing work on your HVAC system, look into Home Ducting Options and Choosing the Best Insulating Duct Materials for Your Air Ducts before you get started.