Really good conversion eff., really bad lauter eff.

[VanHolton]

Reading through some posts recently by The Pol and Kaiser about separating conversion and lauter efficiencies, I thought I'd give it a shot to start troubleshooting my efficiency problems. Yesterday I brewed an imperial brown and had 99.6% conversion efficiency (based on Kaiser's spreadsheet) but my efficiency into the kettle was only 65%. Something must have gone badly in my sparge.

Now I have a 9.5 gallon kettle and was trying a thinner than usual mash (1.6qt/lb) and with a 16.25 lb grain bill, that put my strike water volume at 6.5 gal. With just a hair over 2 gal absorbtion, that leaves me with 4.5 gal first runnings. I'm shooting for 5 gal into the fermentor (a six gallon carboy) so I single batch sparge with only two gallons. I know, I know, I should've used more sparge water, but I didn't think it practical to try to boil off three gallons or something in the boil. To try to get the most for my money with the thick sparge, I vorlaufed 2 quarts twenty times. The gravity of the second runnings was 1.043. First runnings was 1.072. My target post-boil gravity was 1.081, assuming 75% efficiency, but I got 1.077. Not too bad, but I'd like to do better. As it stands, it's fermenting vigorously so that's good news!

How would you guys have approached this situation?

 

[Bobby_M]

Well, you can't use imperial beers as an efficiency benchmark. As you saw, the thinner mash left you with very little sparge and that is where lauter efficiency suffers. Mash a lot thicker and retest for conversion efficiency. If you're still in the high 98-99%, then you're fine. If you stuck with say 1.25qt/lb, you'd strike with 5 gal, runoff 3, and sparge with 3.5. Again, if your conversion stays good at 1.25qt/lb thickness, your lauter efficiency will go up by a few points.

The only other remaining thing is to test for lauter dead space. How much wort stays behind after you fully drain?

 

[mummasan]

Kaiser describes a way to determine what eff was left in the spent grain. I think the instructions are to dump 1qt/lb of cold water into your spent grain, stir, then drain and take a hydro sample. Use the reading with his chart - it can give you a better idea about what happened with your eff. (I plan to do this on my next brew.)

For five gallon batches, I think it is important to tweak your process slightly for big grain bills (over 14 lbs). Whether you plan to do a longer boil, mash thicker to be able to have a bigger sparge or something else.

 

[sudbuster]

Reading through some posts recently by The Pol and Kaiser.........
<SNIP>
How would you guys have approached this situation?

Personally, I'm quite tired of it all, and will continue to follow Noonan's advice. I achieve 92 % brewhouse effiiciecy. Noonaan's recipes are given assuming no less than 90% brewhouse efficiency. To each his own....