P Trap Condensate Drain

There is a major difference between using p traps on sanitary applications and condensate removal from an ac unit and that is.

P trap condensate drain.

A central air system routes condensation through a u shaped trap located in the drain line just outside the air handler. P traps have to be installed on a suction system so a p trap was added. The ac equipment is set on the slab floor or curb and it is the mechanical contractor s job to install a p trap. A p trap is needed to block air and allow condensate to drain properly.

See below for an image of a sink p trap which works the same way. If fan is located before the coil in the system the fan will push small amount of air and water down condensate drain. Trap failures due to freeze up drying out breakage blockage and or improper installation can compromise the seal against air ingestion through the condensate drain line. Air conditioning units are shipped from the factory to the job site without a condensate drain trap.

See water won t flow up hill so the 180 degree turn in the drain causes water to get trapped in the bottom of. Traps with insufficient height between the inlet and outlet design deficiency on draw through systems can cause the drain to back up when the fan is on possibly causing. Air was coming in from the outside and creating a dam which was preventing the con. If fan is located upstream of coil fan will pull water up drain line counter to water flowing down drain.

What is a p trap.