What is the minimum vertical drop from the outlet of the condensate drain pan to the inlet of the P trap?

What is the minimum vertical drop from the outlet of the condensate drain pan to the inlet of the P trap?

• A. 1 inch
• B. 2 inches
• C. 4 inches
• D. 3 inches

Answer: (D)

The nitrogen of this question is about ensuring a proper gravity-fed condensate drain into the P-trap and keeping the trap sealed. The outlet of the condensate drain pan must drop far enough to feed water smoothly into the trap inlet and allow room for the trap arm and the trap itself to be installed below the pan. A minimum vertical drop of three inches gives enough clearance for the fittings and ensures the trap remains primed, so water stays in the trap to block sewer gases and prevent backflow or siphoning when the system is operating. If the drop were smaller, the connection could be too shallow for reliable drainage and trap protection, which is why three inches is the standard minimum.

The nitrogen of this question is about ensuring a proper gravity-fed condensate drain into the P-trap and keeping the trap sealed. The outlet of the condensate drain pan must drop far enough to feed water smoothly into the trap inlet and allow room for the trap arm and the trap itself to be installed below the pan. A minimum vertical drop of three inches gives enough clearance for the fittings and ensures the trap remains primed, so water stays in the trap to block sewer gases and prevent backflow or siphoning when the system is operating. If the drop were smaller, the connection could be too shallow for reliable drainage and trap protection, which is why three inches is the standard minimum.