Low Eff. From incomplete mash or sparge?

[sj90]

Hi there,

I recently switched from batch to fly sparge. Partial to see if I could increase efficiency and part just wanting to try it. Batch sparging I regularly was at 68-70% going pre-boil. This is lower than what I've see most listing, so I figured I'd see if it could be improved.

I've only done two batches with my fly sparge setup, but I'm getting roughly the same efficiency. Last batch I took a few gravity readings to try and figure out what is going on. I've listed them below, if you see anything that would show if it is my mash not getting the sugars out, or the sparge leaving too much behind, please let me know.


System:
5 Gal THD cooler
8" diameter "manifold" with ~30 1/16" holes
Gravity fed sparge with arm
1-2" of water above bed
flow ~.75 quart per minute

Gravity:
Start of sparge: 1.083
End of sparge: 1.012
Pre-Boil: 1.051
OG: 1.057
I mixed the mash after sparging, Vourlof: 1.030

Recipe:
7.5 lb American - Pilsner 37 1.8 62%
2.65 lb American - Wheat 38 1.8 21.9%
1.75 lb Flaked Wheat 34 2 14.5%
3 oz Rice Hulls 0 0 1.6%
Mash @152F, 1.2 qt/lb
Sparge @166F

Any insight would be helpful. The beer I'm making is still good, I just like improving things.

Thanks,
Spencer

 

[jalc6927]

Shoot for good beer from improving your consistency and forget about efficiency. There is no correlation between good beer and efficiency, unless of course you’re brewing 1000’s of gallons per year, than you’ll save a few $$$

 

[friarsmith]

68-70% isn't bad. If the beer is good and reproducible, run with it. (1) Decreasing the flow rate into the kettle a little bit from your stated 0.75 qt/min, (2) stirring the mash once or twice mid-way through (before recirc/sparge) and (3) bumping up the sparge water to 170* should help a bit.

You may also find that grists heavy with flaked ingredients run a few points lower than all barley grists, no matter what you do.

 

[doug293cz]

At a mash thickness of 1.2 qt/lb, your initial runnings SG should have been about 1.098 - 1.099 if you had gotten 100% conversion during your mash. Your conversion efficiency is somewhere around 0.83/0.99 = 0.84 or 84%. This is quite a bit lower than the readily achievable ~95%. If your mash efficiency was 70%, then that would make your lauter efficiency about 70/0.84 = 83%. A good fly sparge should result in about 90 - 95% lauter efficiency for normal OG beers.

You can improve your conversion efficiency primarily by crushing your grain finer. Extending mash time may help as well.

The lower than optimal lauter efficiency may be due to use of a manifold rather than a false bottom in your MLT.

But, as previously noted, consistency is more important than high efficiency.

Brew on

 

[sj90]

Thank for the responses. The beer is most definitely good, I'm just a tinkerer and enjoy that part of homebrewing almost as much as the beer. It's fun to try new things and see how they effect the brew days and final product. I had done around 20 batches with batch sparging with fairly consistent results. If I can improve something by fly sparging I'd like to try, even if just for $#!ts and giggles.

Doug, thanks for that post, that's exactly what I was looking for. The crush is currently out of my control, but I will monitor initial runnings SG for the next few batches and see if I'm consistently low. I've been contemplating getting my own mill for a while, so this might just be the justification I need. But I'll try extending the mash to 90 min? first. Also, how do you calculate the initial running SG? I tried to figure that out before posting and came up empty.

On the lauter efficiency, I'll try a slower and more consistent flow rate and higher temp first. I think it got a bit high flow around the mid point of both batches and I had to slow it down. Not sure if it's changing due to the lower SG or what.

Thanks again!

 

[doug293cz]

The info on initial runnings SG can be found here, including a nice table so you don't have to calculate anything.

Yes, as the sparge proceeds, the SG as well as the viscosity of the runnings drop. The lower viscosity will result in higher flow rates, so some adjustment during fly sparging may be needed. Slower sparging rates should help mitigate the flow issues caused by a manifold.

Brew on

 

[sj90]

Awesome, thanks! I thought it would need to be calculated based on the recipe, but that is much easier.