What is the purpose of a trap on a condensate drain?

• A. To cool the condensate
• B. To prevent sewer gases from entering the living space while allowing condensate to drain.
• C. To increase drainage rate
• D. To filter debris

Answer: (B)

A condensate drain trap is there to create a water-filled seal that blocks sewer gases from entering the living space while still letting the condensate drain away. The water in the trap acts as a barrier to gases moving up the drain line, so even if pressure changes or backflow occurs, odors and harmful gases are kept out. At the same time, the trap does not hinder the liquid flow—the condensate simply drains through the trap to the building drain or floor drain. This isn’t about cooling the condensate, speeding up drainage, or filtering debris; it’s about preventing sewer gas intrusion while allowing normal drainage. Keep the trap from drying out so the seal remains effective; a dry trap can allow odors to pass.