A VAV discharge is necked down right after the box
An immediate neck-down after a VAV can choke airflow, raise static, and cause heat/reheat or noise problems. Keep discharge transitions approved and preserve airflow area where possible.
VAV [tag] is necked down immediately after discharge to clear [obstacle]. I checked available space and downstream run. Do you want a longer transition, flatter equivalent-area duct, box shift, or detailer direction?
Watch out
Do not slam a small neck-down directly onto a VAV discharge just to clear another trade.
Check
Confirm VAV tag, discharge size, downstream duct size, and obstacle causing the neck-down.
Check VAV manufacturer/submittal and project detail for discharge requirements.
Look for reheat coil, noise, high static, or TAB concerns downstream.
Measure space for a longer transition or wide/flat duct shape.
Ask before changing size/shape at equipment discharge.
Steps
Confirm VAV tag, discharge size, downstream duct size, and obstacle causing the neck-down.
Check VAV manufacturer/submittal and project detail for discharge requirements.
Look for reheat coil, noise, high static, or TAB concerns downstream.
Measure space for a longer transition or wide/flat duct shape.
Ask before changing size/shape at equipment discharge.
Say this to your foreman
VAV [tag] is necked down immediately after discharge to clear [obstacle]. I checked available space and downstream run. Do you want a longer transition, flatter equivalent-area duct, box shift, or detailer direction?