Heating / January 25, 2022

How Your Furnace Affects Your Indoor Air Quality

The type of furnace you have, its efficiency, and its operation affect your indoor air quality (IAQ). Specifically, furnace conditions and operations will affect the levels of humidity, temperature, and air pollution in your house. Below is an overview of how some of these effects occur.

Extreme Humidity Levels

Both high and low humidity levels affect your IAQ. Low humidity dries out your airways, irritates your eyes, and leaves your skin dry and itchy. High humidity makes your skin clammy and uncomfortable. High humidity also encourages mold growth, which can trigger respiratory health issues.

Your furnace’s operation determines whether it can cause low or high humidity. For example, a combustion furnace in a conditioned space can indirectly lower your home’s humidity. As the furnace burns indoor air, your house will admit makeup air from outside, which might be drier than your indoor air. The dry makeup air lowers your indoor humidity.

You might experience the opposite problem with a high-efficiency furnace. Such a furnace has a second heat exchanger that extracts heat from the exhaust gases and cools them into a liquid. The furnace has a condensate drain to get rid of the liquid. The condensate can increase indoor humidity if something blocks its drainage and the water accumulates or leaks in the house.

Combustion Emissions

Combustion furnaces produce different byproducts of combustion, such as carbon monoxide (CO) and carbon dioxide (CO2). Both gases are dangerous: CO is poisonous and can lead to fatal accidents, while CO2 causes suffocation by displacing oxygen in the air.

Ordinarily, these combustion byproducts do not infiltrate your indoor air but safely flow out of the house through the flue vents. However, they can affect your IAQ if:

  • The heat exchanger cracks, for example, due to overheating, and allows combustion gases to mix with the heated air
  • The flue vent suffers damage and allows spent gases to leak in the house
  • Something blocks the flue vent and forces spent gases to backdraft into the house

Anything that blocks the normal flow of spent gases can release combustion gases in your home.

Extreme Temperatures

A malfunctioning furnace can affect your IAQ by overheating your house or leaving you in the cold. For example, the furnace might overheat your house if:

  • The thermostat malfunctions and sends wrong signals to the furnace control board
  • Someone accidentally sets the temperature unusually high
  • The thermostat reads an incorrect temperature (for example, a low temperature due to a draft)

On the other hand, your furnace might leave your house cold if:

  • The ignition system malfunctions and the burners cannot light
  • The furnace does not get adequate combustion air to produce enough heat
  • The thermostat malfunctions or reads erroneously high temperatures

Anything that interferes with the furnace’s normal heating cycles can lead to temperature extremes. Note that extreme temperatures are uncomfortable and can affect your health (for example, by interfering with your sleep quality).

Debris Circulation

Lastly, your furnace’s operation can also increase the amount of dust circulating in your home. Discover some ways your furnace can contribute to dirty indoor air:

  • Low-efficiency air filters can allow moderately sized particles to pass through and circulate in your home
  • Dusty air can infiltrate leaky ductwork and pass through the supply vents
  • Dirty filters can contribute to pollution if some particles dislodge and circulate with the heated air

You might experience allergic reactions and respiratory problems, such as asthma flare-ups, depending on the particles and your health.

Don’t suffer poor IAQ in silence. Mauzy Heating, Air & Solar can diagnose and solve your IAQ problems to allow you to enjoy comfortable environments. We have over 50 years of HVAC experience. Contact us for a quote for all your HVAC services.

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