How to Know if Your Ducts Are Clean (and Keep Them Clean)

Wondering how to know if your ducts are clean? Well, there's a simple answer and a slightly more complicated answer. Here's the simple one:

Grab a flashlight and look inside your return ductwork. If you see a layer of gunk, your ducts are dirty.

If you're thinking, "Ok, that sounds a little too simple," you're onto something! While it's easy to visibly confirm whether your ducts are dirty simply by looking inside the return or glancing at the blower wheel, you don't just want to know if the ducts are dirty. You want to know whether you should clean them - and how to make them stay clean.

And that is a whole other conversation.

Why clean your ducts in the first place?

Before we talk about whether you should clean your ducts (and how), let's consider why you might want to. In some homes, ducts stay pretty clean on their own. Typically, these are homes with well designed, properly installed, well sealed ducts and a properly sized, well functioning HVAC system. The homeowners use a quality air filter. They also either don't have pets or they clean up after them very well.

If you were to wipe your finger inside the return ducts in one of these homes, you might lift up a thin layer of dust. That's normal and isn't cause for duct cleaning.

However, air duct cleaning is needed when your ducts contain any of the following:

  • Thick layers of caked on dust and/or debris
  • Pet dander
  • Droppings from insects or other pests

These contaminants can enter your indoor air any time the HVAC system is running. They may aggravate allergies or asthma and make you feel sick. In many cases, they also just stink.

When you can verify that your ducts are gunky - and your home's air is making you feel unwell - duct cleaning may very well help you. Here's how to clean them properly and make sure they stay clean.

1. Have a professional clean your ducts.

This isn't a DIY project. Properly cleaning your ducts requires specialized equipment that isn't readily available to consumers. Pros use truck-mounted or large portable vacuums with special extension attachments. They'll also run a HEPA filter during the cleaning process to prevent contaminants from entering your home after they've been stirred up by the equipment.

When you hire a duct cleaning company, make sure you choose one that:

  • Owns and maintains specialized duct cleaning equipment
  • Will also clean the blower motor and indoor coil when needed
  • Replaces your air filter as part of the service
  • Offers the option to inspect your ducts for leaks and seal the leaks after the cleaning

Note that duct cleaning is more effective for hard pipe ducts than for flex ducts. It's the difference between scrubbing a dirty plate and scrubbing a towel that's flapping in the breeze. It's just… harder. If you have flex ducts, they can still be cleaned; however, replacing them might be a better option since even the most effective duct cleaning equipment (and service provider) faces limitations.

2. Seal your ducts after cleaning them.

This factor, more than anything else, will help prevent your ducts from getting dirty again in the future. Not all duct cleaning companies seal ducts after cleaning them, but they should! Here's why:

Duct leaks are often the cause of dirty ductwork.

It's really that simple. When your return ducts are leaky, a lot of the air entering the ducts doesn't come from inside your home. It's being sucked in from your attic, crawlspace, or wherever your return ductwork runs.

Think about what's inside your attic air: dust, fiberglass bits, insect and rodent dross. And let's not forget crawlspaces: mold, mildew, more dust, more fiberglass bits, more insect and rodent dross. It's pretty gross.

When ducts are leaky, that stuff gets sucked inside your HVAC system, coats the inside of your ducts, and circulates throughout your indoor air. You breathe it in all the time. Cleaning your ducts will get rid of what's already there, but it won't prevent the leaks from making your ducts dirty again.

That's why we strongly recommend having your ducts sealed after you have them cleaned. Otherwise, you'll just have to clean them again and again. Yes, it's an additional service, but in the long run it's a cost effective, preventative measure.

Oh, and we know how to get your duct leakage down to 4%. If you know someone who can get it even lower, let us know.

3. Install a media filter.

Even with duct sealing, ducts can keep getting dirty. If you have kids or pets, they'll get dirty sooner. Ditto for homes where the return grilles are at the floor. For this reason, it's a good idea to get a high quality air filter. Even as more gunk starts to coat your ducts, less of it will get into your indoor air when you've got a good air filter to capture it.

Media filters are the way to go. Unlike the throwaway 1" filters you get at big box stores, these high-MERV filters barely restrict airflow and do a better job filtering air. They also only need to be replaced twice per year.

4. Consider replacing your ducts.

When your ducts are really old, poorly designed, and/or improperly installed, replacing them can make more sense than cleaning them. Paying for duct cleaning when your ducts are in poor shape is kind of like getting a new transmission for your 1995 Dodge Stratus. Sometimes, you just have to play taps and let it go.

When we install new ductwork, we do it right. You get a proper duct design for your home and HVAC system (we follow the ACCA's Manual D for ductwork design). Your ducts will be sized to suit, installed properly, and sealed as tightly as possible.

You'll benefit from clean, sealed ducts and better HVAC performance.

Speaking of HVAC performance, consider having your ducts replaced if you're already planning to replace your HVAC system. This can be a good way to get cleaner, better designed ducts at the same time.

Think you need duct cleaning?

Give us a shout! Our team serves all of Metro Atlanta. We'll visit your home, listen to your concerns, and examine your ductwork. Sometimes, duct cleaning makes sense and is likely to solve your problems. But not always.

We'll find the best possible solution, whatever that is. Our team always works with you to determine the smartest fix for your indoor air quality issues.