How Does a Poorly Maintained Duct System Affect Indoor Air Quality?

If your home is equipped with an HVAC system, it may seem like you no longer need to worry about the Indoor Air Quality (IAQ). IAQ is affected by a wide range of factors, an improperly maintained HVAC and ventilation duct systems are typically at the top of the list.

Poor air quality can cause a wide range of health issues, right from headaches or congestion to asthma and other breathing disorders. It’s essential to keep the air duct and ventilation system in great shape, since its maintenance and upkeep has a direct connection to the quality of air you and your loved ones are breathing!

Let’s look at the top 5 effects of leaky or damaged air duct systems:

  1. They Pull In Bad Air – Pollutants from outside your home can get into the ventilation system if there are any leaks or gaps in the HVAC return ducts. When you’re running your air conditioner or heating, the system could be pulling in and distributing contaminants throughout the house!
    Since return ducts pull air into the unit and then supply it through the system after conditioning, it’s crucial to check for contaminants around them. Bad air doesn’t just come in from outdoors. It can also be pulled into leaky ducts from rarely-used, musty spaces like attics, basements and crawl spaces.
  2. They Create Negative Pressure – It’s not just leaky return ducts that increase the intake of bad air. From the supply side of the HVAC system, duct leakage leads to its own set of IAQ concerns by creating negative air pressure inside your home. This increases infiltration of outside air, as the system tries to balance the air pressure.
    If the amount of air being supplied through the ducts (after conditioning) is less than the amount that went into it, the negative pressure will cause more air to leak into the house through attics, crawl spaces, basements, windows and doors. Since this is unfiltered air, it can raise pollutant levels indoors.
  3. They Raise the Risk of Back drafting–When you use a combustion appliance (water heater, cooking range, oven, etc.) the harmful gases emitted by it exit your house through a flue or chimney. However, if there’s negative pressure in the air around these appliances, these gases can get pulled back into the house (back drafting).
    Back drafting poses a serious risk to IAQ, especially in terms of carbon monoxide poisoning. It’s more likely to be an issue if you run multiple combustion appliances in the same room, like a clothes dryer and a furnace. Leaking return ducts and even closed room doors near the central return vent can create pressure imbalances.
  4. They Reduce Humidity Control – Humidity is often the main culprit to blame for diminished IAQ, since it encourages the growth of mold. Mold spores thrive in a moist, warm environment, which may be found within certain sections of a leaky duct system.
    Most HVAC systems have built-in moisture control, but if humid air is entering the house from outside or inside sources (damp basements, for instance), this functionality may be affected.
  5. They Affect HVAC Performance – While bad air is typically filtered out by the HVAC, excessive leaks can put more pressure on these systems than they’re designed to handle. This can lead to performance or efficiency issues, increasing energy consumption in addition to affecting IAQ and comfort.

In addition to return and supply ducts, make sure you check the air handler cabinets, filters and filter housings for leaks. If any of these are damaged, the HVAC system may not be filtering the air inside your house at all.

If you want to improve the indoor air quality for your home, get your heating and air conditioning installed and maintained by a licensed HVAC company like Service Champions. Set up a regular service schedule with us today!

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