Kegging

Hi I just went out and got my self a kegerator now who can tell me the best way to gas up a 18l keg what psi should I be setting it at.

how many feet of co2 line and what temp are you keeping it at?

It's about 3-4 feet, with temp what is your recommendation

i have around 6' lines with 38 degrees. i keep the co2 at 11 lbs. you can adjust any of these variables, though. you can keep it cooler, have longer lines, different pressure...

At 3.5' of line in a 38F fridge, I'd set it to 20 psi for 2 days (for rapid carbonation) then back it down to 9 psi for a few days before you start serving. Cheers!

CO2 line length is irrelevant. What length and ID are your beverage lines? I'd install 10 feet of 3/16" ID tubing per tap, that way you can carb up a little higher without worrying about foam. In terms of what pressure to set it at, that depends on beer style and your personal preference.

Here's a good chart:
http://www.kegerators.com/carbonation-table.php

Basing your carbonation level off of your existing line length is silly and a completely backwards way of thinking. Why let the quality of your beer suffer because your line lengths are insufficient? Let the style of beer determine the carbonation level, then adjust your system as needed to get you there.