How to Know If You Should Clean, Repair, or Replace Air Ducts

Lawrence Bonk
Written by Lawrence Bonk
Updated October 27, 2021
A HVAC system in front of a brick wall
Thelma Lanteigne / EyeEm/EyeEm via Getty Images

Know when it may be time to get your ducts cleaned or kiss them goodbye

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An air duct is the last stop before the cold or hot air created by an HVAC system hits your home. In other words, it is the last chance to filter out dust, allergens, and other airborne impurities before it is breathed in by friends and loved ones. There are a number of factors that determine whether you can clean an air duct or if you will have to hire a local HVAC repair pro. In some cases, you should even throw out an unusable duct and replace it with a new one.

But how do you figure out your best course of action? Here is everything you need to understand about when to clean an air duct, when to replace it, and when to get rid of it and start over.

When to Clean an Air Duct

Knowing how often you should clean your air ducts isn’t so cut and dry. The National Air Duct Cleaners Association recommends hiring a pro to clean your ducts every three to five years, while the EPA says you can typically skip cleanings unless you notice signs of visible mold or excessive dust. However, this decision will vary depending on how often you use your HVAC system, what type of ductwork you have, and if you are experiencing an influx of allergens in the home. 

Here are scenarios in which you should clean your ducts rather than repair or replace them.

Metal Ductwork

If your ductwork is metal and features no interior liner, a thorough and professional cleaning is often the answer. Metal ducts are the standard for newly built homes, so your ductwork is likely eligible for a good cleaning. Flimsier ducts, such as those made from fiberboard or plastic, may not stand up to an intense cleaning.

Improper HVAC Installation

If someone didn’t install your HVAC system properly, it might lack a good seal. In other words, air will leak throughout the system and, then, into the home. This allows an accumulation of dust and other debris into the atmosphere. 

This solution could require cleaning as well as a repair of sorts. Hire a local energy consultant to conduct a blower door test to help you determine exactly where any leaks could be occurring. If a bad air seal is the culprit behind dirty ducts, clean the ducts and hire a pro to reseal the HVAC system.

When to Repair an Air Duct

A professional repairing an air conditioning duct
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There are times when a simple cleaning won’t cut it, as the problem lies with the internal mechanisms of your air duct or somewhere else in the HVAC system.

Leaky Ducts

If you notice hot and cold spots in your home or pay higher-than-average utility bills, you could have a duct leak. A technician has an arsenal of tests at their disposal to check for leaks. 

If your air ducts are leaky but are otherwise in good condition, there is no need to replace them. Save some money by hiring a pro to plug up those leaks instead. On the other hand, cleaning a leaky air duct will do nothing to fix the leaks. Professional repair is your best bet.

Poorly Sealed Registers and Grills

Sometimes the problem lies not with the duct itself but with how it connects to your wall and the rest of the HVAC system. If your ducts aren’t properly sealed via the register or the grills are loose, dust, and related debris will accumulate throughout your HVAC system and home. Additionally, poorly sealed ducts lead to insects and other critters. Don’t fret, though. Calling a contractor to reseal your ducts will fix the problem and, as a bonus, positively impact energy efficiency.

When to Replace an Air Duct

A man adjusting an air duct
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Sometimes, the problem is so severe that you should scrap the ducts entirely, buy some new ones, and have them professionally replaced. Your local HVAC installation pro will have specific answers regarding duct replacement, but here are some scenarios in which that might be your best option.

Mold Overgrowth

Ah, the dreaded “M” word. Mold is the worst, and if your ducts have become heavily contaminated with the nasty fungi, it could be time to replace and move on. Though the EPA says cleaning the ducts is sufficient for mild bouts of mold, severe outgrowths typically require replacement, especially if the ducts have rusted. Of course, don’t replace it until you have removed the mold at the source, or it will just pop up again. Call in a professional mold removal expert before replacing the ducts.

Twisted or Broken Ducts

Flexible plastic air ducts, otherwise known as flex ducts, are common in homes and are often found in the attic. Flex ductwork is typically a wire coil covered by a thin, flexible plastic wall and wrapped in insulation and foil backing. They are easy to install and generally come pre-insulated, making for happy homeowners. The problem? Flex ducts can easily twist, tear, or break. A twisted duct will need a replacement.

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