I have been brewing with a converted keg as my kettle for a couple years now. I really enjoy the size of it and sturdiness. One thing that chronically plagues me is my draining process. I have a weldless bulkhead fitting through the side. I used to just make a 7 gallon final batch size so I could drain out of it 5 gallons. But I got tired of leaving ~28% of my batch behind. So I have worked with several types of dip tubes. I have used a copper tube to the center of the kegs base. That set up works, but I am also pulling all the cold break and hop debris into the fermentor. I have tried a copper dip tub that suck from the side of the kettle, but you still leave about 15% of the batch behind, and pull some break and hop debris.
I am also considering upgrading to a plate chiller. Mainly to save time. Many friends of mine have them and it cuts a good 30-40minutes out of the brew session. I need that with the family situation making it tough to find time to brew. But to use one of those you really need to clear your wort of most all the hop debris.
I was using a small 9 inch false bottom and a centered stainless dip tube for a few batches. That worked great when using whole hops. But the thing seems to twist sometimes under the weight of my immersion chiller, so you end up sucking hops again.
There is also the issue of losing siphon when the wort falls below the level of the ball valve in the kettle. I used to have a polysulphone disconnect system on the valve and a piece of tubing running into the kettle. But the tubing had an ID of 3/4inch. As wort flow slowed toward the end of the batch, air would sneak up the tube and break the siphon and stopping the flow. I think I fixed that by going to a brass 1/2inch ID barb fitting with 1/2inch tubing. (Which I actually like better for sanitation issues behind the disconnect in the valve port).
On my last batch I used a homemade hop-stopper. Similar to one of these:
That worked well but I still pulled some air from somewhere and lost flow prematurely.
So why am I putting this long post up? Well I was wondering how others are separating their wort from their hop debris. More importantly, am I the only idiot with siphon issues out the dip tube in the kettle?