Interesting, the copper chiller I use is basically a miniaturized version of that cascade chiller. Does the beer flow through the pipes or down over them? Mine has only 4 tiers so it isn't very efficient and I have to recirculate the hot wort for about 45 minutes to get it down to pitching temps. The extended recirculating is what makes me suspect aeration and copper exposure as a potential source of the issues I'm having.
On a side note, in my setup the hot wort flows from top to bottom while the cooling water flows the opposite direction to maximize the temperature differential at the point of exit.
View attachment 690346
Question, if you are recirculating in a closed system essentially, where would the aeration take place? I can't see clearly from the picture where the output hose extends to, but I assume it is not just splashing back down into the pot, correct? Probably submerged or running down the side.
I would examine how you rack into the fermenter, pitching temp, what you ferment in, material wise, do you leave the co2 blanket undisturbed during fermentation, how are you controlling your fermentation temperature, have you tried leaving in the primary an extra week, how you rack into your keg, are you exposing your beer to sunlight at any point, purging the headspace in the keg before burst carbonating, etc.
The wort chilling at some point crosses over to a temperature where you want to aerate the wort before pitching anyway, so I guess I am still skeptical it is your chiller oxidizing the wort right out of the gate when it might be the yeast aren't happy enough in their ideal temp range or initial cell count (too high perhaps). I also have to say the character of my beers have improved when I started saving and repitching yeast, compared to first gen out of the package. The Hefeweizen batch I posted above was a fifth generation repitch of s-04 that had previously gone through making different styles (english bitter, stout). Seems to make better beer in subsequent batches, but you need to measure the slurry and not overpitch or you'll be stuck with the lack of fermentation character.
One more thought, I think a lot of emphasis is placed on the yeast alone in a Hefeweizen for developing characteristic aroma and flavor when I believe it also has a lot to do with a quality pale wheat malt, properly crushed. I got a very good results with s-04 after all, but I used a german malster for both my pale wheat and pils malt. I have found domestic malsters lack roundness of flavors so I just prefer imported malts. Maybe the reason 62F worked well for me was it allowed the wheat malt aroma and flavor to be prominent, aided by low IBU (10) and high chlorides in the mash water.
It would be easier to examine these things than change your brewing equipment, and you could always borrow an immersion chiller just to rule out your suspicion.
Whoo Hoo!! 
![Craft A Brew - Safale S-04 Dry Yeast - Fermentis - English Ale Dry Yeast - For English and American Ales and Hard Apple Ciders - Ingredients for Home Brewing - Beer Making Supplies - [1 Pack]](https://m.media-amazon.com/images/I/41fVGNh6JfL._SL500_.jpg)
