related question:
I've just installed a whirlpool port on my blichmann kettle (that was a scary hole to cut). I've been looking to just dump pellet hops into the boil and not have to worry about dealing with the bags.
So from the BK it goes to march pump back into whirlpool port for...
First off, what was your FG reading? Don't rely on airlock activity to determine when a beer is done.
Did you get this flavor before dry hopping? I like to try the beers all thru the process to be able to determine how the flavors are changing (hopefully no off flavors/oxidation/etc...).
14...
Sweetness should not mellow like hop flavor.
Are you sure you pitched proper amount of yeast and/or aerated the wort properly after cooling?
I have also heard that the caramelization of DME can product unfermentable sugars and adding late in the boil can help.
Another reason to quickly move...
If you using a Brutus system, you don't need really need to recirculate the entire time. I've got 3-20 gallon Blichmanns using a heat exchanger in HLT to keep mash temps within 1-2 degrees for entire conversion time (like you). Vorlaufing doesn't need to be done the entire time. Try insulating...