My CFC was with 20' of 3/8 tubing, but I already had the tubing. Used a $15 el cheapo garden hose from home depot, two 1/2" T's and a couple of 3/8" to 1/2" reducers, plus a 1/2" copper union to connect it to hose from the kettle.
20' is plenty. Gravity fed (15+ minutes for a 5 gallon batch). JohnQ has a good thread in the equipment forum...