Static field route #18932

What do I do when an AHU condensate trap is too shallow and the pan overflows?

Equipment Connections: RTU, AHU, VAV, Fans & Louvers🟨 CHECK FIRSTV189 answer-gap expansion

📖 Verified core answer

A draw-through unit can hold water in the pan if the trap does not overcome negative pressure. Verify unit type/static and rebuild the drain trap per manufacturer detail before water damages the cabinet.

Open in Field Rescue Open category

Field verification checklist

Confirm whether the coil/fan arrangement is draw-through or blow-through.
Check the manufacturer condensate trap detail and required dimensions for the actual unit/static.
Look for shallow trap, missing cleanout, wrong vent location, no slope, blocked drain, or pan outlet issue.
Check for water damage near electrical/control compartments.
Stop/contain water before it damages equipment or ceiling.

Ask foreman

The AHU drain pan is overflowing and the trap looks shallow/wrong at [unit]. I checked drain slope and unit type. Do you want the trap rebuilt per the manufacturer detail before restart?

Text to foreman

Route options

AMake the field correction only if it is within your assignment and the approved method.

BHold and document the condition if the fix affects airflow, access, life safety, pressure class, rated assemblies, equipment, or another trade.

CBring the foreman/detailer the location, what you checked, and what decision you need before cover, startup, or rework.

Do not do this

Do not copy a generic shallow P-trap detail onto every AHU.

Why this matters

A bad condensate trap can flood the unit, damage controls/electrical areas, stain ceilings, and create startup headaches.

Verification basis

Approved drawings/specs, project coordination drawings, manufacturer instructions/submittals, shop standards, foreman/detailer direction, employer policy, and AHJ/code requirements.