TinnerFlow™2nd YearEquipment ConnectionsGREEN · Standard Correction
A fan coil or fan-connected unit hard-piped to duct can transmit motor vibration. Add the approved flexible connector/isolation detail and make sure the duct is independently supported.
Rotating equipment can send vibration straight into rigid ductwork if there is no break between the unit and the metal duct. That hum can travel into the ceiling grid and occupied space.
The fix is to install the project-approved flexible connector/canvas/isolation detail at the equipment connection, with enough slack and proper clamping/fastening. The duct still needs its own support; the flex connector should not carry weight or be stretched tight.
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.