Working on old Capitol Hill homes, I commonly find problems with condensate discharge lines in many HVAC systems. Even when I find them currently functioning properly, they are often built out of code. The common code problems I find with HVAC condensate discharge lines are as follows:
1. Sizing — the building code requires 3/4″-minimum diameter piping to be used.
2. Materials — the building code allows for copper, CPVC, PVC, and polyethylene pipe to be used for condensate discharge drains.
3. Interference with other systems — condensate discharge drains are not permitted to enter into overflow pans, or drains for other systems.
Following the code allows pipes to discharge with lower tendency for backup and destruction from flooding caused by backups.
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