I'm setting up this machine, well trying to and am wondering how much room the 7800 dn really needs. It's calling for almost 6 feet off of one side and around 7 feet around another side. Is this clearance due to heat or just service needs? Will it void a warrranty if it is located in a spot without this amount of space?
I don't know where you got those numbers but they are not even similar to the Install guide.
You seem to be using the room size numbers.
The room needs to be at about 7 feet by 5 feet in size to accommodate distance from the wall (3.9 inches for the right side and back)
Front side needs about 4 feet(50.5 inches), left side about a foot and a half (15.4 inches) Those numbers are in the install guide linked above, the screenshot below is from the user guide
No they would not just up and void your warranty for no reason, but they certainly would if they found it in a smaller room, no ventilation, door closed and a printer that clearly over-heated.