finding drain pipe under basement floor
I'd like to tap into the drain pipe under my basement floor to provide a drain for the condensate and a humidifier on my furnace, being one to trust gravity much more than pumps. Any good hints as to how to map out the locations? I was once told that the cleanout was set to face in the direction that the pipe runs, is that reliably true? Also wondered whether an infrared camera could see them after running hot water through. The logic of how the various standpipes might be connected is ambiguous.