Why is my Filter Dirty?

The Wrath of Your Dirty Furnace Filters

While the average lifespan of an HVAC system is approximately 20 years, one dirty furnace filter can cut that time in half – or worse. It is crucial to regularly replace your air filters to avoid a catastrophically expensive, potentially dangerous situation.

How Can I Tell If I Have a Dirty Air Filter?

In order to determine whether or not you have a dirty AC filter, you may look for the following signs:

  • More dust has been piling up in your home.
  • Your air filter appears gray in color and seems to be covered in pollutants.
  • You detect unusual increases in your energy bill.
  • The cycles in your HVAC system have increased in length.

Why Can't I Just Live in Filth?

Simply accepting a clogged air filter is never a good idea. Not only can the dust cause health issues due to increased dust and allergens in the air, but your HVAC system and furnace filter can malfunction, decreasing the flow of heat or air in your home or freezing condensation on the cooling coils (also preventing proper air flow). Below are a few specific problems that can occur as a result of a dirty air conditioner filter:

  • Recycling of air filled with pollen, dust, mold, and other allergens trapped in the filter.
  • Rise in allergic reactions like clogged sinuses, headaches, itchy eyes and throat, and more.
  • Inflation of energy bills due to an upsurge of up to 15% energy usage.
  • Growth of bacteria, as a result of frozen coils.
  • Ultimate destruction HVAC system, financially costing you thousands.

So What's Really Clogging up my Filters?

Most homes in the US have a central AC unit that cools the house. In these kinds of systems, air circulates from room to room through ductwork. On its way to the unit, air passes through a filter that removes large particles that could settle on and damage the unit if they don’t get trapped. The question on most people’s mind is - Why does your air filter get so dirty?

Pollutants that Clog Air Filters

  • Dust, dirt, and fibers
  • Indoor smoke
  • Pet dander
  • Pollen
  • Mold spores
Dust, dirt, and fibers - Dead skin cells, dirt tracked in from outside, and fibers from upholstered furniture, carpet, and bedding all contribute to household dust. As these pollutants are whipped up, they enter the ductwork and clog up the furnace filter.
Smoking indoors - Cigarette smoke wafts through the air when you smoke indoors, making its way to the filter and clogging it up faster than if you choose to smoke outside.
Pet dander - Dogs and cats shed, which gets hair everywhere. Much of this hair is swept up into the ductwork, where the furnace filter catches it so it can’t recirculate back into your home.
Pollen - Even though flowers grow outside, it’s possible for pollen to hitch a ride on clothing, shoes, hair, and skin. Furnace filters for allergy season are most effective at trapping pollen particles for cleaner indoor air.
Mold spores - Efficient furnace filters for the home trap mold spores as they travel through the ductwork. If excess humidity dampens the filter, mold could start to grow here if you don’t change the filter frequently enough.

    Other Factors that Clog Up Your Filter Faster & How to Help Prevent a Dirty Furnace Filter

    Cold weather - When the temperature drops, your furnace works harder to keep your home warm. This sends more air flowing through the filter and increases the amount of particles that become trapped there, dirtying your filter faster than normal.
    Thermostat set to on - This setting means the furnace blower runs all the time. Auto is a better setting for energy efficiency and helps your filter last longer as well.
    A home full of contaminants - More pets, people and dust in your home cause more contaminants to fly through the air. If you have multiple pets and people living at home, you should expect your furnace filter to become dirty faster.
    Infrequent air filter replacement - The general guideline is to check your filter once a month and change it if it looks clogged. No filter should be installed longer than three months. Try to change your filter with the changing seasons to keep up with this recommendation, or follow our guide on how often to replace your furnace filter.

      Avoid a Clogged Air Filter, and Replace Yours Today

      Now that you know what causes your air filter to become dirty, it’s time to stock up on replacements. Remember, choosing high-efficiency air filters for extreme seasons can be of great help to keep the air in your home clean.


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