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Mold in Air Ducts? How It Got There & How To Get Rid of It

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mold in air ducts

Noticing signs of mold in your air ducts?

ODORS. An unusual or musty odor is often the first sign of mold in air ducts. In many cases, you’ll smell it before you can see it. If you notice a musty or moldy smell that goes away when you are not using your air conditioning or heating (if they share ducts), that can narrow the cause down to some part of your HVAC system.

Mold can smell wet, rotten, or stale. If you notice a recurring problem, particularly in areas with poor ventilation or a lot of moisture, get it checked out right away.

VISIBLE MOLD. Look for the first signs of mold around AC vents, in the ducts and in the drip pans. Condenser coils pull moisture out of the air and into drip pans, and if these become clogged they create the perfect environment for mold to grow.

Keep in mind that mold spreads through spores, which are tiny particles that are invisible to the naked eye. That means you won’t necessarily see actual patches of mold growth right away. By the time you do see a noticeable amount of mold, infestation can be quite serious. At that point, you need professional help to get rid of the mold and make sure it doesn’t come back.

SYMPTOMS. If people or pets in your home start exhibiting symptoms whenever the AC is on, mold in air ducts might be the cause. If there’s enough mold in or around the vents, it can spread in the air, causing allergy like symptoms such as headaches, nausea, irritated nose and throat, and itchy eyes.

What causes mold to grow in air ducts?

Mold grows in ductwork when two things are present: moisture and warm temperatures. A warm, humid environment has the ideal conditions for mold to form. A humid climate along with poor ventilation, or anything that traps moisture in your walls and causes condensation, can lead to mold in air ducts.

Here are some of the HVAC problems that can contribute to these conditions and ultimately mold growth:

If your AC unit is oversized for the space you have, one of the problems that it can cause is mold in air ducts. Larger units can cool small spaces too quickly and turn off before dehumidifying the air, leading to excess moisture. This moisture can build up in your rooms and ductwork. If you see mold shortly after a new installation, check to make sure you’ve got the proper sized equipment for the space you have.

Setting your AC on a very low temperature can sometimes lead to mold around the vents. When the cool air from the vents meets the warm air in the room, the temperature difference can cause moisture in the air to condense on surfaces in and around the vents. If that moisture builds up and never gets a chance to dry out, it can lead to mold growth. This is called the temperature differential and usually takes about 20 degrees of difference for moisture to form. If you don’t notice it for a while, the moisture can make its way into your air ducts.

However, if your ducts have leaks that let in warm air, this temperature differential can cause the same kind of problem. The difference between the cold air in the ducts and warm air in the walls can cause moisture to condense on the ducts, giving mold a perfect environment to grow. In this case, you’ll need extensive duct cleaning with mold remediation, and you’ll want to make sure to seal up the leaks in the ducts to prevent the problem from returning.

Why you need a professional to remove mold

Hiring a professional to clean may seem like an unnecessary expense, but technicians can take care of mold and help prevent it from coming back more effectively and safely than you can do yourself.

First of all, scrubbing mold with ordinary cleaners won’t make it go away. Regular cleaning products will leave behind enough mold for it to easily grow back. Professionals have the proper equipment to protect themselves and your home or business from not only the mold, but the chemicals they use to clean it.

You could also accidentally damage your HVAC system if you try to clean mold in air ducts yourself. Professionals know what to look for and how to treat your AC with care. Professional ductwork cleaners have HVAC training, so they’ll be familiar with your system and know how to clean it without damaging it. They also use the correct mold growth inhibitor products to prevent it from coming back, and they know how to properly dispose of tools to prevent contaminating other areas.

Learn more about professional duct cleaning services:

Refrigeration Preventative Maintenance Contracts

How to prevent mold in future

Once you’ve taken care of the mold in air ducts, it’s important to make sure it doesn’t happen again. Getting an HVAC preventative maintenance plan is a great way to keep an eye on the mold and keep your HVAC system healthy. It can help prevent the causes of mold by making sure there are no issues that can cause moisture leaks. Regular maintenance prevents breakdowns and keeps your cooling running smoothly.

Another thing you can do to take care of your HVAC is consider a periodic duct cleaning service. Duct cleaning is usually not included in routine preventative maintenance. You’ll definitely need duct cleaning after discovering mold in air ducts, but also consider getting a regularly scheduled cleaning, especially if you live in a humid climate or have trouble with mold that keeps coming back.

If you have issues with mold after taking these steps, it’s time to look into an underlying cause of humidity in your home or business:

  • Keep supply and return vents clean and clear of obstacles to prevent condensation leading to mold in air vents.
  • Consider adding ventilation in rooms with high humidity, such as bathrooms and kitchens.
  • Check for plumbing leaks in the walls. Slow water leaks might not be noticeable right away, but over time they create an ideal breeding ground for mold in air ducts, and also water damage in your space.
  • Use a dehumidifier in a very humid environment, such as an indoor pool room or basement space. A dehumidifier can help keep the air dry enough to prevent mold.