mold in hvac

What mold is? what are reasons for mold growth inside air ducts? and can we prevent it? in this article we will cover everything about mold in HVAC.

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what mold is?

Mold is a fungus that grows in the form of multicellular filaments called hyphae. there is thousands of mold fungus species and they are all require moisture for growth. Of course the mold is an important part of our ecological system considering his decay abilities. It can also grow on food and in a lot of cases it makes it toxic and dangerous to eat. In this article we will focus on mold in HVAC and air ducts systems.

Mold on bread

what causes the mold in hvac system?

In fact, mold and mildew needs moist to establish and grow. In areas that humidity is very high, it provides perfect environment for the fungus to grow and spread fast. Now you may ask where the water coming from? it’s quite simple, what happens when hot air coming in contact with cold surface? it’s creates ‘condensation’. Condensation is the process where water vapor becomes liquid, like to take a water bottle out of the fridge. In this case, the most of the year the AC systems are on ‘cool’ mode compare the attic’s temperature which is high. the result of this contact is condensation inside air ducts, vents and furnace.

can mold in hvac make you sick?

Even tough mold has an important part for our ecological system, for humans mold can be extremely dangerous. The term spore is often associated with diseases caused by bacteria, but most of the health problems caused by mold can be for people with weak immune systems and people with respiratory problems. In addition, as mentioned, various molds produce toxins that can be dangerous to humans and live by ingestion and respiration. Not all mold types are toxic, and the term “toxic mold” refers to specific spices only.

few signs for mold inside my hvac system

Odor – Musty odor from your ductwork can be a serious sign for mold inside your system, especially while you run the system.

 Visible – Visible mold on the ‘vent grilles’ or on the ceiling can point on the fact there is a mold colony inside the system. In this case you can open the covers and check it out or either call to an expert to inspect it.

Illness – Mold can cause some serious problems as itchy eyes, headaches, red eyes, itchy nose and even respiratory problems. If someone feeling one of these symptoms you should call an expert for an inspection.

Water leaks – if there is a water leak near the air ducts – call to professional to inspect and fix it, or, to ensure that no damage was caused.

Mold on air vent

can i remove mold myself?

it is important to note, in order to get results that meets the requirements – Air duct cleaning is not a DIY project. Only professional equipment can remove the mold completely and safely from the AC system.
To eliminate the fungus it’s necessary to clean it with chemicals approved by the EPA related to HVAC and air ducts.


  1. According to the Applied and Environmental Biology UV light has been proven to prevent mold fungus inside HVAC systems (for further reference press Here).
  2.  Inspections – it’s recommended to inspect the system every 2-3 years to check the Plenum box and ductwork.
  3.  Replace filters – every 3 month replace your Return’s air filters or in the attic unit.
  4.  Attic fan – attic fans are used to reduce the heat in the attic and to minimize condensation inside the ductwork.
  5.  Life Expectancy – air ducts are effective for 30-40 years. The insulation around it wear and no matter how good you’re gonna clean it the mold will comeback again and again. If your ductwork is over 30-40 you should seriously consider to replace the air ducts.
UV Lights

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