Why Your New AC Needs More Return Air Than Your Old One
What Is Return Air – and Why Does It Matter?
Your AC system works like a pair of lungs. Supply vents blow air out, and return vents pull air back in so the system can cool it again. If the system can’t pull in enough air, it can’t push out enough cool air.
Why Older Systems Seemed to Work Fine
Older systems had looser coils, weaker blowers, and lower filtration. They could muscle through bad ductwork. New systems are efficient but require proper airflow.
A Simple Example: Why Your Current Return Is Too Small
Common setup: one 20×25 return and one 12×12 return. Using the rule: grille area x 2 ~ CFM. 20×25 = 500 sq in -> 1000 CFM. 12×12 = 144 sq in -> 288 CFM. Total ~ 1288 CFM. A 5-ton system needs ~2000 CFM. The system is short by 700+ CFM.
What Happens When Return Air Is Undersized
Hot/cold spots, humidity issues, long run times, noise, reduced cooling, higher bills.
The Fix: Give the System the Airflow It Was Designed For
Add return vents, upsize existing returns, ensure proper airflow. Improves cooling, humidity, noise, efficiency, and lifespan.
Analogy
Your old AC was like an old pickup truck. Your new AC is like a modern turbo engine. It’s efficient, but it needs to breathe. Right now, your system is trying to inhale through a straw.