Fan Performance Curve Basics
Understanding fan curves helps troubleshoot airflow problems.
What You Might Be Looking At
graph showing CFM vs static pressure for specific fan model
Apprentice words: fan chart, blower curve, airflow chart, pressure vs flow
Trade terms: fan performance curve, fan curve, system curve, operating point
Check First
What Not To Do
Don't assume catalog CFM achievable in all conditions. Don't increase fan speed without checking motor capacity. Don't ignore high static pressure readings.
What can go wrong: Underperforming system, occupant complaints, excessive energy use, fan overload and failure
Better Foreman Question
System showing higher static than design. Check for closed dampers or fan operating off curve?
Verify With
Reference type: manufacturer data, ASHRAE
Source to verify: Fan manufacturer performance data, ASHRAE Fundamentals Handbook
Safe wording: Fan curves are manufacturer-specific. System curves depend on actual installed conditions.