Tell someone or document it before you close it up.
Mixed systems tied to wrong equipment
A wrong equipment tie-in sends the right duct to the wrong place. Verify the equipment tag, system tag, and airflow path before the connection is sealed or insulated.
I want to confirm I am connecting the right duct to the right unit. I have [duct/system tag] going to [unit tag], and the drawing shows [confirm/conflict]. Can you verify this before I make the final connection?
Watch out
Do not tie duct into equipment until the system and airflow path match the drawings.
Check
Verify the equipment tag on the unit against the duct system tag on the drawing. Do not connect based on location alone when multiple units are nearby.
Trace the airflow path on the drawing: supply to supply, return to return, exhaust to exhaust, outside air to outside air. Confirm the duct run belongs to that equipment.
Physically check the tag or label on the equipment before final connection, especially in mechanical rooms with similar units next to each other.
If you suspect a wrong tie-in, stop before sealing. Trace back from the unit and from the duct run until the tags match.
Document the tag conflict with a photo of the equipment tag and the drawing callout.
Steps
Verify the equipment tag on the unit against the duct system tag on the drawing. Do not connect based on location alone when multiple units are nearby.
Trace the airflow path on the drawing: supply to supply, return to return, exhaust to exhaust, outside air to outside air. Confirm the duct run belongs to that equipment.
Physically check the tag or label on the equipment before final connection, especially in mechanical rooms with similar units next to each other.
If you suspect a wrong tie-in, stop before sealing. Trace back from the unit and from the duct run until the tags match.
Document the tag conflict with a photo of the equipment tag and the drawing callout.
Say this to your foreman
I want to confirm I am connecting the right duct to the right unit. I have [duct/system tag] going to [unit tag], and the drawing shows [confirm/conflict]. Can you verify this before I make the final connection?