What is the requirement for condensate drain lines?

The requirement for condensate drain lines is that they must directly drain into a trapped drain. This is vital because a trapped drain helps prevent sewer gases from entering the HVAC system and the occupied space, ensuring that the indoor air quality remains safe and healthy. A trapped drain also allows for the proper drainage of condensate, which is crucial for the efficiency and longevity of the air conditioning system.

Proper drainage is important to avoid water damage and mold growth from stagnant water, and the trap acts as a barrier against any reverse flow of sewer gases. The design of the trap is critical to maintain the siphon effect that keeps the sewer gases at bay without obstructing the flow of condensate. This requirement aligns with local plumbing codes and best practices in HVAC system installation and maintenance.

In contrast, draining into open air does not provide any backflow prevention and could lead to water accumulation or air quality issues. Direct connection to the sewer line may lead to similar problems as it doesn't include the necessary trap. Insulating the drain lines may provide some benefits, but it is not a primary requirement for their function.