Serving the Chippewa Valley and the North Central Areas of Wisconsin
Tuesday 23 March 2021

Mold in Your Air Ducts

Posted by at 1:18 AM

Mold is a relatively common household problem.  Mold is found virtually everywhere, but when it begins to proliferate beyond reasonable standards it can cause problems ranging from structural damage to health issues.  One place in the home that mold can be found is within the HVAC system and ductwork. 

What Causes It?

Mold growth, in general, occurs in the presence of warmth, moisture, and an organic food source.  This means that any warm and humid environment is the perfect breeding ground for mold.  While a perfectly functioning HVAC system shouldn’t have mold issues, there are some common problems that can cause mold growth in your air ducts. 

  • Leaking Ducts: Ducts that are leaking let in air that is a different temperature than the air being pushed through the ducts.  For example, if you’re running the air conditioner, your leaky ductwork will let in warm air.  This temperature differential can result in condensation and a buildup of moisture on the ductwork, allowing mold to grow.
  • Oversized AC Unit: You’ll want to make sure that the air conditioning unit you’re using is the correct size for the space you’re cooling.  A unit that is too large for the space will cool too quickly, causing it to turn off before dehumidifying the air.  This, once again, leads to excess moisture buildup both in your home and ductwork.
  • AC Set Too Low: Very cold air from the vents meeting very warm air in your home can cause condensation buildup on and around your vents.  This moisture can make its way into the ductwork if it goes unnoticed, leading to mold growth both around the vents and inside the ducts. 

Is it Dangerous?

As mentioned, mold is present virtually everywhere.  There is a particular threshold for determining how much mold is too much mold.  Also, depending on the species of mold, spores can cause various respiratory and other health issues.  Because of this, mold is typically only a health concern when it begins to proliferate out of control and when the spores are disturbed.  This makes it particularly tricky when it’s found in your HVAC system.  Mold spores travel with airflow, so if mold has taken hold in your ductwork, it will travel throughout your home every time you turn on your heat or air conditioning.  If you think you have a mold issue in your HVAC system, it needs to be addressed right away. 

Warning Signs

Knowing the signs of mold growth within your ductwork can help you determine if you have a problem or not.  The following are three of the most common signs that there is mold in your HVAC system.

  1. Visible Mold

Visible is clearly the most obvious sign of a mold problem in your ductwork.Common places to find visible mold are on your covers, on the vents, and inside or on your furnace or air conditioner.

  1. Musty Odor

A musty odor when your run your heat or air conditioner is a sure sign that there is mold somewhere within the system.Your HVAC system will disperse mold spores throughout the home, and, with them, their distinctive earthy smell.

  1. Illness and Allergies

Breathing in mold spores can cause allergy symptoms as well as exacerbate pre-existing conditions like asthma.  If you’ve noticed that you have itchy, watery eyes, a scratchy throat, or trouble breathing since turning on your HVAC system, it’s a good idea to have it inspected and treated for mold.