February 28, 2023
If a return air duct is undersized, your HVAC system can behave as if it’s breathing through a straw. The strain can cause your heating and cooling system to work harder and inefficiently. Your energy bills may increase and you may face expensive repairs and system breakdowns. Improperly sized ductwork can even shorten the life of HVAC components. To help avoid such situations, take action when you recognize these symptoms of an undersized return air duct.
If there’s not enough return air, your living room can be 10℉+ warmer or cooler than, for example, the bedrooms. Not enough return air in summer can cause rooms close to the central unit to be cooler and those farther from it to be warmer. In winter, rooms farther from the furnace can be too cool. An improperly sized return duct is one of the most common reasons for this (another being an AC or furnace issue).
A telltale symptom of an undersized return air duct is if the room closest to the air conditioner has more airflow than rooms farther away from it. That’s because air pressure is high near the unit. But the farther you go, the lower it is.
It can be difficult to tell if the air pressure in one room is different from that in another. You can use a barometer to determine if this is the case. While not a common item in homes, a barometer can be purchased from many retailers online. Sometimes, you can feel pressure imbalances in your ears; if they hurt in one room and not in another, you may have a ductwork problem.
Lick your finger and place it near a vent that’s producing airflow. While this won’t measure airflow as a quantity, it can help determine air velocity. If the return air doesn’t feel sufficient, have the system evaluated by a professional.
Undersized return ducts can cause up to 20% of the conditioned air in your home to escape. This occurs due to air pressure and not a hole in a duct. The excess pressure is caused by exhaust air staying in a room longer. The room may become uncomfortable and stuffy. In extreme cases, the air duct can collapse.
Poorly installed ductwork is a common reason for frequent HVAC repairs. It can cause unexpected breakdowns. Jumper ducts above doors (or walls near doors) and undercut vents can boost airflow but are only a temporary fix. The system won’t maintain proper airflow and will be strained if undersized ductwork isn’t replaced.
Reduced airflow isn’t always a sign of an undersized duct. Other reasons include blocked supply registers; keep furniture and drapes away from vents so the air has a place to go. A dirty air filter can restrict airflow as well; therefore, clean or replace the filter regularly. An air duct leak is another potential cause; it can significantly decrease efficiency, so call a professional for a ductwork inspection.
Your HVAC ductwork is what allows the system to breathe. It cannot work properly if any ducts are undersized. At Service Champions, our experienced technicians replace improperly sized ducts and perform detailed calculations before installation. This ensures all ducts and components are carefully selected based on the needs of your home. To learn more, schedule your visit online or call 833-600-0991.