So I built a Keggle. Now I need to know what tubing...

is best to use to drain it into my fermentation bucket. I have a 3/8 hose barb on the ball valve.

Since the wort will be cold by the time you drain, it doesn't really matter. I use silicone tubing for mine. But, it isn't really necessary. Just make sure it's something food grade.

That is, assuming you use an immersion chiller. If you're using a CFC or plate chiller, the wort will be hot, and silicon's probably best, at least between the keggle and the chiller.

Did you use/install a 1/2" ball valve and then use a 3/8" barb fitting in it? All my valves, fittings, and hoses are 1/2" (ID for valves and hoses). I use silicone tubing between the keggle and plate chiller, then back again to the keggle (recirculate) before running into the fermenting vessel (also the same 1/2" ID silicone tubing). Using the same tubing makes it easier to put it all together since you don't need to keep the low temp side separate from the high temp side.

Even if the OP uses an IC, I think silicone tubing is the better route to take. It will last a loooong time and you can boil it if it gets nasty inside (if you don't clean it well after use). Plus, it tends to be more flexible than the vinyl tubing of the same size.

For now I just have a 3/8 copper wort chiller that I will be using to cool the wort.

Yes, I have a 1/2 BV with a 3/8 hose barb. I may swap it out for 1/2 depending on how I feel after my first brew with the keggle.

Flow rate will be much better if you have a 1/2" barb on that valve. I never understand why people would put restrictions, intentionally, in their systems like that. It's not like it's a huge cost difference between the two barb fitting sizes. :cross:

Not too worried about flow rate right now. If it takes an extra 15 minutes, so be it. If I decide to switch to the 1/2", I can do it at a later date. My main concern is getting the keggle up and running.

if you have to switch it, you also need to switch hose. 1/2" is the standard, and a 5/8" barb will let the 1/2" silicone tube stretch it over and flow even better

Thanks slakwhere I will keep that in mind.