Installing new dishwasher

Well, my 20 year old dishwasher finally bit the dust - no not my wife LOL. So I get to install a new one soon. I need to add an air gap vent on my sink as the old dishwasher just used a looped drain line. I'll need to drill a hole to install the vent (stainless sink). Does anyone know the hole size for these air gap vents? I'd like to buy a step drill bit except they're pretty expensive so I'll have to use some bits I've got or borrow a step bit. I guess it doesn't matter which side of the sink I drill the hole as long as it doesn't interfere with the dish sprayer hose. Also, I'm going to rent a drill powered drain snake to clean everything out before the new dishwasher goes in - any tips on using the snake? Thanks.

 

V8 - I recently installed a new dishwasher (Whirlpool). The installation instructions that came it required an air gap only if the drain hose is connected to house plumbing lower than 20" minimum above the floor or subfloor.

 

You can also plumb the drain without an above-the-sink air gap, by making yourself literally a trapped stand pipe from 1 1/2 inch pvc. You make the top of the stand pipe go up fairly high up under your sink, to the left or right of your sink basins. This trapped stand pipe would then be connected up with the kitchen sink drain. Then you simply stick the diswasher drain hose into the stand pipe some, and secure it, so it can't come flying out of the standpipe, upon discharge.

Not that you might want to do this method, but it is a legal option. I work on condos that have employed this method.

 

Thanks for the replies. I have an uncut cabinet panel in the dishwsher space because the old dishwasher had a drain pipe that exited low so the previous homeowner drilled the hole near the floor. On the new one, the instructions say to route the drain hose through a hole in the side cabinet panel a minimum of 32" above the floor and route it back down to the disposal. I can drill a hole up to about 33" high. I guess I can forget about installing the air gap vent. 32" seems a bit high but I guess the higher the better for backflow prevention.