When to Have Air Ducts Cleaned: A Complete Guide

Do you know the condition of your home’s air ducts? If you’re like most homeowners, probably not – and that’s OK. After all, air ducts are typically hidden behind walls, under floors, or in hard-to-reach areas like basements, attics, or crawlspaces.

While duct cleaning isn’t something you need to do on a regular basis, there are certain situations where it becomes necessary. HVAC.com explains when it’s time to consider duct cleaning, and when it may even be time to replace your ductwork entirely.

When to Consider Air Duct Cleaning

According to the U.S. Environmental Protection Agency (EPA), air duct cleaning should only be performed when necessary. Here are a few of the most common reasons to have your ducts professionally cleaned:

Visible Mold Growth

Mold thrives in dark, damp environments. Your HVAC system can offer the perfect conditions, especially during humid summer months. If mold begins to grow inside your ductwork, it can worsen allergies, asthma, and other respiratory issues.

Obvious signs of mold in your air ducts include:

• A musty or mildewy odor coming from your vents
• Visible mold growth around supply registers or return vents
• Increased allergy symptoms or breathing difficulties indoors

Because most ductwork isn’t easily visible, consider hiring a professional HVAC technician or indoor air quality specialist to perform an inspection. They can identify mold and offer options for remediation.

If mold is found on hard surfaces like sheet metal ducts, it can usually be cleaned. However, if your ducts are insulated and become moldy, the insulation can’t be effectively cleaned and should be replaced, according to the EPA.

Rodent or Insect Infestations

If the thought of rodents or insects making a home in your air ducts makes your skin crawl, you’re not alone. Unfortunately, it happens more often than you’d think. Mice, squirrels, and insects can chew their way into your air ducts and create nests. Unfortunately, they often bring more than just an unwelcome presence.

Rodents and insects can leave behind:

• Droppings and urine
• Nesting materials
• Foul odors
• Bacteria and allergens

When these contaminants are found in your ducts, they can circulate throughout your home, worsening your air quality and potentially making you sick. You may also notice chewed-up materials near vents or hear scratching sounds in the walls.

In severe cases, an infestation can even damage your ductwork and HVAC system, causing reduced efficiency and higher utility bills. If you suspect vermin in your ducts, you’ll need both pest control and professional duct cleaning, and potentially repairs or replacements if the damage is extensive.

Excessive Dust and Debris

Have you noticed a thick layer of dust building up on your furniture shortly after cleaning? Or maybe puffs of dust coming from your vents when the HVAC system kicks on? These are red flags that your ductwork might be clogged.

Over time, ducts can accumulate dust, pet dander, and construction debris, if your vents aren’t well sealed. When these materials build up to excessive levels, they can:

• Restrict airflow
• Make your HVAC system work harder
• Decrease system efficiency
• Spread allergens throughout your home

According to the EPA, you should consider having your ducts cleaned if you see visible dust buildup or particles being released from supply registers. Regularly changing your HVAC air filter can help prevent this issue, but if it’s already a problem, a professional cleaning may be the best solution.

Tips to Keep Your Ducts (and Air) Clean

Even if you don’t currently need duct cleaning, there are several proactive steps you can take to maintain a cleaner, healthier HVAC system and avoid issues down the line like unwanted mold and pests.

1. Consider a Whole-House Dehumidifier

High indoor humidity levels can lead to mold and mildew growth, especially when relative humidity levels climb past 60%. A whole-house dehumidifier keeps moisture levels balanced year-round, making it harder for mold to thrive in your ductwork or around your HVAC equipment.

2. Upgrade to a Variable-Speed Air Conditioner

Variable-speed air conditioners don’t just improve comfort and efficiency; they also run more frequently at lower speeds, helping to filter and circulate air more consistently. This can reduce humidity and help prevent airborne particles from settling in your ducts.

3. Seal Gaps and Entry Points

Rodents and insects can find their way into your ductwork through tiny gaps or unsealed access points. Consider having a professional seal your ducts and inspect them for vulnerable areas, especially in attics, crawlspaces, and basements. Sealing these gaps also improves energy efficiency by preventing conditioned air from leaking out.

4. Stay on Top of HVAC Maintenance

Routine HVAC maintenance is key to clean, healthy ducts. Change your air filter every 1-3 months, depending on usage and indoor air quality. Schedule seasonal tune-ups to catch minor issues before they turn into major repairs.

5. Install an Air Purification System

If your home has allergy sufferers or pets, or if you’re sensitive to indoor air quality issues, a whole-home air purifier can be installed directly into your HVAC system to help remove dust, dander, and even some airborne pathogens.