Nasty taily flavor in lees?

[Wild Bill]

Long story short I modified my still arrangement to include a thumper using a 15.5 gallon keg same size as boiler. Perfect I thought for running 21 gallons of sweet feed wash. I ran 11 gallons + of clear wash in blr and 9+ dirty in thumper. Ran a fast strip run and things went as planned but I did notice what smelled like tails way early. Did a spirit run with low wines from strip in blr and 1.5 gallons of water in thump. Ran slow and by the 10th 300ml jar I smelled tails which seemed way early. Finished run and collected 2.6 gallons down to 25%. Let air a couple of days and was really taken aback by the nasty taily smell and taste in the whole run including the hearts. Well I decided to run the whole works back through single foot low and slow. Ill be damned if that tails flavor didn’t come through on the entire run as well. The only thing I can think is that those flavors are in the yeast bed and wash in the thumper of the original run. Being I ferment in kegs I decided to just hook the keg up lees and all in the thumper position. I am beginning to think this was a mistake. Any thoughts or experiences on this from the brain trust?

[still_stirrin]

...Being I ferment in kegs I decided to just hook the keg up lees and all in the thumper position. I am beginning to think this was a mistake...

Yep, that probably is your problem. What’s worse...you may have “baked in” the taste, like a scorch. I would NEVER run yeast trub (lees) in a boiler intentionally. I always try to clear the wash as best as I can. Or at least rack off of the yeast into the boiler.
ss

[Wild Bill]

Yep, file it under things not to do. It seemed so perfect in conception but suffered upon execution. The taste is not completely overwhelming bad in the hearts section so I will oak it and call it a long term experiment. Learning all the time I are. The good news is the the thump mod worked great and the runs went quite smooth. I will however siphon off and leave the yeast bed in the fermenter next time.

[Wild Bill]

Well I did another run with only clear wash in thump keg and still got tails smeared in heart section on spirit run. I think from doing research that line size/heat up time, as well as the single inlet outlet approach on my thumper are causing this smearing. A remodel of my thumper setup is already under way. I will run 2” off boiler keg into its own port all the way to bottom of thump and then out the top center with a new 3” column. On the upside, my soldering is getting much better as a result of all this remodeling lol. Stay tuned for thump version 2.0.