New MLT...Efficiency Suffering

Several brews ago, I finally upgraded my MLT from a 5 gal square beverage cooler to a 10 gal rubbermaid from Home Depot. The copper manifold I created fit perfectly in the 5 gal cooler, but due to the increased area of the 10 gal, it is a bit small for the space in the 10 gal. The manifold also does not site perfectly snug at the base of the new MLT. Regardless, I didn't think this would significantly affect my efficiency considering many just use a braided hose.

With my old system, I would usually max out my mash water around 3.5 gal for 60 min at 154F and then continuous sparge with 170-180F until I reached about 7.2 gal. I was able to achieve efficiencies between 70 and 80 consistently.

With my new setup, I've been struggling with efficiency. First batch, I used the prescriptive approach of mash volume to grain ratio and then did my usual 170-180 continuous sparge until I reached 7.2 gal. There was very little sparge water since I had much more mash volume. Efficiency was terrible.

Next I tried a single batch sparge with the same prescriptive mash volume. Again efficiency was terrible and the sparge volume was minimal.

In my most recent attemp, I cut down my mash volume to about 3.5 gal and then did two batch sparges with near boiling water (190 ish). My efficiency was 61 which was acceptable but still not where I want to be.

I really want to dial my new system in and figure out why my efficiency has suffered. The next things I plan on trying...

1. build a new manifold
2. mash with 3.5 gal then continuous sparge with 170F-180F
3. reduce gap in my mill

Thoughts???

With just mesh braid you might get a channelling effect on the flow of the water with fly sparging. A false bottom for even flow of water will help or batch sparge.

Are you sure you are getting the grains well mixed with the water (do you add water to grain or grain to water)?

What are the volumes/gravity for first and second runnings when you batch sparged?

How are you adding the sparge water when you fly sparged?

Did you change anything else at the same time? (Thermometer, grain source, mill?)

What do you mean by proscriptive approach to mash/grain ratio?


Sorry for all the questions, I am just trying to get a better idea of what is going on.

I typically add about 1 gal of water, then grains, then the rest of the water and mix well.

Volumes for each batch sparge were 3 gal.

When I fly sparged, I used a quart pitcher and made sure there was about 1 in of water over the grain bed.

No other changes.

By prescriptive, I mean 1.5 qt/lb of grain.

*One thing I did notice was that my water grain absortion was pretty minimal. Could that be a sign of improperly milled grains?

What's minimal water absorption? Also, were these high gravity grain bills? What were the grain bills? How much dead space do you have in the MLT?

By absorbtion, I mean the amount of water absorbed by the grains...ie water loss. OGs were 1.060 to 1.075. Not sure on dead space.

Perhaps I should rephrase. Roughly how much absorption did you get per pound?

Low apparent absorption could be a sign of grains that weren't mixed with the water well leading to lower efficiency. That could come from poor mix or bad crush. Did the way you crush your grain change at the same time you got your new MLT? If not it would not make sense to blame the crush.

Do you know the gravity of your first runnings? At a ratio of 1.5qt per pound it should be about 1.082. If your first runnings gravity (FRG) is way below that then crush or mix (conversion efficiency) is your culprit.

If the FRG is about right then problem is in your lauter. That would mean looking at tun dead space or leaving water in the MLT after your kettle is full.

Try 1.25 to 1.5 quarts per pound of grain for your mash. Make sure you have a good crush on the grain. I then measure my collected wort and determine what I need for the boil. I usually take half of that and do a first sparge. I measure again and do a final sparge to get to boil volume.

I have read that it is a problem fly sparging with a manifold or braid.

Another thing to look at: are you leaving liquid behind in deadspace in the tun. I tip my cooler so that I get all the wort out. It took a number of brews for me to dial in all my equipment but I am now pretty much hitting my numbers with my 10 gallon Rubbermaid cooler and water heater braid.

I did not change the way I crush my grains and unfortunately I did not take a FRG reading. I will do that in the future.

OK, so here's an example...

If I have 18 lbs of total grain and I use 1.5 qt per lb, I would have 25.5 qts or 6.38 gal of mash water. If I assume 0.125 x lbs of grain is lost through aborbtion, I would lose about 2.25 gal. If I'm targeting 7 gal of preboil volume, total sparge volume would only be 3 gal. So, I would do two batch sparges with 1.5 gal each. Is that correct?

guitar510 said:

I did not change the way I crush my grains and unfortunately I did not take a FRG reading. I will do that in the future.

OK, so here's an example...

If I have 18 lbs of total grain and I use 1.5 qt per lb, I would have 25.5 qts or 6.38 gal of mash water. If I assume 0.125 x lbs of grain is lost through aborbtion, I would lose about 2.25 gal. If I'm targeting 7 gal of preboil volume, total sparge volume would only be 3 gal. So, I would do two batch sparges with 1.5 gal each. Is that correct?

Click to expand...

I wouldn't try to sparge 18 pounds of grain with 1.5 gallons of water! That would be thick like cement. Instead of two rounds of batch sparging, just use one addition.

I'd probably mash a little thicker, say 1.25-1.33 quarts/pound, so to have more water in the sparging.

Larger grainbills do tend to have lower efficiency due to the reduced sparging amount. That's because you reach your boil volume before you reach the maximum amount of sparge volume. It's ok, just take that into consideration.

For me, with a smaller grainbill I get about 78% efficiency. With a very large grainbill, I may get 70% efficiency. If you know that, you can work with it.

guitar510 said:

I did not change the way I crush my grains and unfortunately I did not take a FRG reading. I will do that in the future.

OK, so here's an example...

If I have 18 lbs of total grain and I use 1.5 qt per lb, I would have 25.5 qts or 6.38 gal of mash water. If I assume 0.125 x lbs of grain is lost through aborbtion, I would lose about 2.25 gal. If I'm targeting 7 gal of preboil volume, total sparge volume would only be 3 gal. So, I would do two batch sparges with 1.5 gal each. Is that correct?

Click to expand...

Use all 3 gallons. You want each run off to be close to the same volume (or as close as possible). Also, if your run off is coming out quickly throughout the entire sparge feel free to tighten the gap on your mill (if you can) a bit. Also, if you have more deadspace in this new MLT you will see a drop in efficiency from that (how much? I don't know).