shared condensate drainage

Hey there, I saw a house today which had both primary drain lines tee’d together. (pic attached)

a part of IMC 307.2.2 says “where the drian pipes from more than one unit are manifolded together for condensate drainage, the pipe or tubing shall be sized in accordance with an approved method.”

Does anyone have access or knowledge concerning these sizes and method?



You are not being very clear here I am assuming you are talking about two separate units and connecting two primary drains together if that is the case I personally would not have a problem with the size of the drain line unless perhaps the tonnage was 4 or 5 ton with lots of coil surface smaller tonnage system will not make that much water that one 3/4 inch line could handle it. I would think in AZ with no humidity there would be no problems. Don’t recall what the IRC states never had an occasion to connect two system together usually both coils are too far apart for this to be a concern.