Troubleshooting center
Duct Design & Sizing
Whether the duct system was ever sized for the air the equipment is trying to move.
Each guide answers the question first, then explains the likely causes in order — duct leakage only where the evidence actually supports it, and a licensed HVAC contractor where it doesn’t.
5 guides in this category
Undersized ducts
Trunks and branches too small for the equipment's airflow will restrict delivery no matter how tight they are.
Read the answerOversized ducts
Ducts sized larger than the airflow they carry can lose velocity, throw and even comfort — bigger is not automatically better.
Read the answerDuctwork sizing check
Correct sizing is confirmed with Manual J/S/D calculations and static-pressure measurement — not by eye.
Read the answerNew AC, old ducts
Not automatically — but the existing duct system needs to be evaluated against the new equipment's airflow, not just reused.
Read the answerExisting ducts vs. new AC
Handling capacity comes down to measured static pressure and physical condition, not the ductwork's age alone.
Read the answer
Find out what your duct system is actually doing.
Schedule a duct leakage evaluation and get measured numbers for your home — not a guess.