I’ve read many posts concerning A/C drain lines. Some folks say it is not legal to run the drain lines into a sewer vent line in the attic. Lots of folks post that their lines are running into a vent line. I know what the pro’s and con’s are but the plumbing codes must vary between states. Here in Louisiana the codes must allow the drain to go into a vent line. How many other southern states allow this? I know that it may only be allowed in the north with a certain type of heater and that the p-trap water evaporates but what do the codes say?
For special provisions in your area check www.municode.com and your local AHJ.