TinnerFlow™3rd YearAirflow / TABYELLOW · Check First
Zero CFM with open dampers usually means a real blockage, closed/tripped device, wrong connection, or disconnected path. Trace the branch before blaming the balancer.
If the unit is running and dampers are open but a branch reads zero, something is stopping the air. It may be internal packing/shipping material, a closed fire/smoke damper, blocked VAV inlet, crushed flex, disconnected duct, wrong tap, or a damper blade not actually moving.
The field move is to trace the air path from main to outlet and inspect at each choke point. Use existing access, registers, camera/mirror, pressure/noise clues, and photos. Cut access only with approval and patch it correctly.
Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.