Everything You Need to Know About Ductwork Chemical Treatments

You’re in your home and you start to notice a sort of musty smell, but you can’t quite tell where it’s coming from. After some detective work, you realize it’s coming from your HVAC system, and you make arrangements to have it cleaned. Here are the different types of cleaning processes and the safe chemicals that duct cleaners use.

Consider the Source...Removal

“Source removal” is defined by the National Air Duct Cleaners Association (NADCA) as the physical removal of contaminants and debris from internal HVAC system surfaces. Those contaminants and debris are referred to as solid matter.

Source removal of solid matter (or, in other terms, gunk) from your HVAC system doesn’t necessarily require any chemicals. Think of it like the dusting you might do with a feather duster or cloth before applying disinfectant.

Sometimes It’s Okay to Be Anti

Antimicrobial, that is. Once an HVAC technician has done source removal on your system, the next thing to consider is antimicrobials. These are chemicals that take care of molds, fungi, and bacteria that build up in your ducts. There are different types of antimicrobials, including:

• Sanitizers

• Disinfectants

• Fungicides

• Antimicrobial pesticides

• Bacteriostat

• Algaestat

Any chemicals that a local HVAC technician uses during the process are required to be registered by the Environmental Protection Agency (EPA). These antimicrobials are typically used on the coils, blower, and duct pipes and are designed to prevent the spread of illness and get rid of all those nasty organisms that could be living in your ductwork.

The danger with antimicrobials is if they’re applied incorrectly by the technician, exposure to them can cause health hazards. Make sure you hire a local duct cleaning professional so you know the job is getting done right.

Angi Tip

Air duct cleaning takes an average of five to seven hours for most households. You can make the job go quicker by removing any obstacles around your HVAC entry points, like furniture.

Kassidy Barber

Content Editor, Angi

Beneath The (Re)Surface

Resurfacing agents are usually the next step after an antimicrobial has been applied. They’re applied to coat the pipes, protect the system from exposure to moisture, and eliminate odors. Resurfacing protects against wear and tear, essentially, so it’s a good idea if you want your ducts to be a) more efficient and b) last longer.

These chemicals are applied after cleaning and will typically require you and any other living beings (family members, pets) to leave the home during application and drying time. The chemicals must be registered with the EPA, but can be hazardous if you’re there while they’re being applied.

Coil Cleaning Compounds

A subset of general cleaning substances, coil cleaners are designed to get the buildup off of your HVAC system’s coils. They’re usually found in one of these formulations:

• Acid, which causes a chemical reaction that releases the soil on coils

• Alkaline, which basically does the same thing as acids, causes a chemical reaction to remove soils, but at the other end of the pH spectrum

• Detergents, which are more complex and fall in the “neutral” area of the pH scale

Dirt on coils is difficult to remove, which is why it requires a special chemical compound. These aren’t heavy-duty cleaners, and the only thing notable about them is the odor. As with any type of cleaner, your technician should make sure all of the chemicals are removed after the cleaning process.

Grease Is the Word

Degreasers are used in the ductwork in places like kitchens where cooking fumes are commonly present or oil is being used. Though these chemicals have a strong odor, as long as they’re used in a well-ventilated area they don’t pose any serious health threats.

Deodorizers

Deodorizers either mask or remove icky odors from your ductwork. They’re generally used if there’s been smoke damage in the home, dead animals, or mold/mildew smells. HVAC technicians will either spray them or put a solid one in the ducts to evaporate over time. 

The problem with deodorizers is because they have a strong scent, if someone in the home is allergic or has a sensitivity to perfumes, they may have a reaction. People with asthma also sometimes have a problem with deodorizers, so if you have those health issues, you may want to skip this one.

Catherine Falls Commercial / Moment via Getty Images

The good news is, regular old duct cleaning is usually enough. You only need to have your ducts sanitized if you have:

• Pets

• Health concerns such as allergies or asthma

• An unpleasant odor in the ducts

• Water leaks/suspected mold

Otherwise, it’s best to have your ducts simply cleaned out every six months to keep your HVAC system in good working order and check for any problems.