10 Signs that the Filters in Your Furnace Are Clogged

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Clogged furnace filters can cause a wide variety of issues that affect the furnace’s health and the people living in the home. Recognizing the signs and symptoms of clogged furnace filters can help homeowners avoid costly HVAC system repairs and health conditions.

All HVAC units bear filters that condition the air you breathe and keep indoor air quality at adequate levels. These filters stop dust, dirt, mold spores, pollen, pet dander, and other debris from circulating the air by filtering them out during the filtration process. Understanding the signs and symptoms of a clogged filter can save time, money, and even good health. 

Warning Signs of a Clogged Air Filter

1. Increased Energy Consumption

When home air filters are clogged, furnaces have to work harder to meet the desired temperature of the thermostat. Fans within the furnace have to work overtime because air can’t flow or be distributed throughout the home as quickly, limiting the efficiency of your air conditioning system.

2. Higher Electric Bills

Due to build-up on air filters, increased energy consumption often translates into higher energy bills. Spikes in electric bill costs, especially in the winter, usually indicate that your furnace filter needs to be cleaned. Be sure to double-check your electric bill and note higher energy usage, as this may mean a clogged air filter.

3. Uneven or Poor Heating

Heat can’t flow or be distributed through ducts as easily when air filters are clogged. Even the best filters are susceptible to becoming clogged due to all of the debris they process. The damage caused by a dirty air filter can make it extremely hard for furnaces to meet the required thermostat temperature.

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4. Short On/Off Cycles

Dirty air filters in furnaces can cause excessive heat to build in the heat exchanger component. Furnaces are designed to shut off when the desired indoor temperature has been reached automatically, turning off the burners and causing the furnace to cool down. Once it has cooled down, the furnace will turn back on. Poor air circulation from a dirty air filter could cause a unit to short cycle.

Infographic ten common signs furnace filters are clogged. First five.

5. Indoor Air Pollution

More allergens can pass through an HVAC air filter that has been clogged, and this can cause a significant impact on air quality and can exacerbate the symptoms of asthma and allergies. One of the reasons your filter gets clogged is that it can’t handle a large number of allergens, dust, and pet dander. This can cause a significant impact on air quality and contribute to poor indoor air quality.

6. Dust

One key indicator of a clogged air filter is an accumulation of dust around your home. In addition to causing indoor air pollution, a clogged air filter can result in an influx of dust and debris in your living space, particularly near vents. If you’re spending more time cleaning and vacuuming during the winter months, a dirty furnace filter could be to blame. 

Infographic 10 signs furnace filters are clogged second half

7. Burning Smells

A burning smell is typical for those who have just turned on their furnace for the first time in several months. However, if you notice a consistent burning smell circulating throughout your home, you could have a clogged air filter. Furnaces require a certain amount of airflow to prevent overheating. If your filters are clogged, the system can’t pull in the necessary air, resulting in a constant burning smell. 

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8. Getting Sick

Poor air quality not only exacerbates the symptoms of those with allergies and asthma, but it can also affect healthy individuals without diagnosed respiratory conditions or allergies. In short, poor air quality can get anyone sick. Dirty furnace filters circulate allergens and contaminants throughout the air and can even cause chronic health problems if inhaled.

9. Adjusting the Thermostat More Often

If you find yourself adjusting the thermostat more often because it’s too hot or too cold, a clogged air filter could be the culprit. When air filters are clogged, they can’t evenly distribute air, resulting in overheating the system or even a colder home.

10. Failed "White Sheet" Test

A white sheet test involves hanging a white bed sheet a couple of inches away from your heating vents. As the heated air blows from the ductwork and vents to the sheet, it will also blow whatever debris is in the system. If the sheet turns brown, gray, or black, it’s time for a new filter. Keep excess debris out of your heating system will extend the lifespan of your furnace.

Do You Require HVAC Maintenance?

Even the best furnace filters can get clogged from time to time; it’s completely normal. However, an unchecked or unchanged filter may result in significant damage to your furnace. For HVAC repairs, maintenance, installation, a tune-up, or any questions concerning your furnace, contact Home Comfort USA today! One of our experienced and highly-qualified technicians would be more than happy to assist you.

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