What is the minimum diameter for A/C condensate drainage?

The minimum diameter for A/C condensate drainage is 3/4 inch inside diameter (I.D.). This size is commonly specified in HVAC codes and standards because it provides an adequate flow capacity to ensure that condensate is efficiently drained away from the air conditioning unit. If the diameter is too small, it can lead to issues such as blockage or backup of water, which can cause damage to the system or the surrounding area.

Using a 3/4 inch I.D. ensures that there is sufficient space for the water to flow freely, especially during periods of heavy condensation, such as when the A/C is operating in high humidity conditions. This size strikes a balance between effective drainage and the physical constraints that may exist in residential or commercial installations. Larger diameters, while capable of handling more flow, are often unnecessary for standard residential A/C systems and could lead to increased costs and more complex installation requirements.