Originally Posted by Bobby_M
You need to talk to the guy with usernam kal. He's messed with this for some time now. The biggest problem you're going to have is all the beer that sits in the lines is going to foul if a few days go between pours.
See my experiences here: http://www.homebrewtalk.com/showthread.php?t=37060
I was going to do approx 15' lines but then changed it all up as that would have been hard to do. You'll need to cool the beer otherwise you'll get massive foaming as it'll have warmed up. With 25-30 feet of length you'd be losing half a pint of beer otherwise for each first pour.
There's no max length really. Bars will go 100's of feet at times but they use glycol loops to chill the beer, pumps to push the beer if it gets too far, and 1/4" or 5/16" poly line with barrier tubing like this: http://www.micromatic.com/draft-keg-beer-edu/keg-beer-trunk-line-cid-1789.html
This is essentially what I ended up doing too, but I only have 4-5 feet outside my freezer.
The other catch is that bars can crank up their PSI as they're only using the Co2 to dispense (not carbonate) and they go through kegs fast enough so that the beer doesn't get over carb'ed by being forced with higher pressures.