TinnerFlow™3rd YearFCU / CondensateYELLOW · Check First
A condensate drain has to overcome unit pressure and maintain drainage. Prime/check the trap, venting, slope, and manufacturer trap detail before water damages ceilings or equipment.
A fan coil or AHU drain may not drain just because PVC is connected. Unit pressure can hold water in the pan if the trap is dry, shallow, unvented, or piped wrong.
Check the manufacturer trap detail, pressure condition, slope, cleanout, vent arrangement, and whether the trap has water seal. Prime and correct the drain only with the approved layout, then watch the pan drain under actual fan operation.
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.