Improving Mash Efficiency?

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Improving Mash Efficiency?

Postby Suthrncomfrt1884 » Mon Jul 27, 2009 5:17 pm

Bare with me, this could be a long post.

I've brewed around 10 all-grain batches so far. All of these batches have been consistantly low efficiencies. I average around 60%. I buy my grains pre-crushed from the LHBS (not somthing they crush themselves), so I don't think it has much to do with my grains. The crush looks to be extremely good.

I use a Gott-like cooler from Home Depot to Mash in. It's got a homemade copper manifold on it for a drain. There's one slit every half inch on the manifold and it sits about 2 inches from the sides of the cooler.

Currently I'm batch sparging until I get my RIMS system fixed. I built a system with 3 kegs and got to use it twice before I realized it needed some more work.

I almost always mash at around 152-156 depending on what I'm brewing and mash for one hour. My sparges have been somewhat fast, so I'm going to attempt to slow it down significantly when I brew today. Hopefully that will help some. As for my sparge technique...I'm not quite sure I'm doing it right. Here's what I do....

I heat sparge water to 185. Slowly add the entire batch of water to my mash. Stir msh well. Allow mash to sit for 20 minutes and then drain after vorlauf (sp?). I then boil for usually 1-2 hours.

Is this about right? The main thing I'm concerned with is my sparge water temp. Should it be raised like this so that the mash is at 170? Or should the water itself be 170? When I was fly sparging, I used 170 degree water, so I'm confused about that.

Thanks in advance for the help.
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RE:Improving Mash Efficiency?

Postby Legman » Mon Jul 27, 2009 8:30 pm

Suthrn,
You'd be surprised at how important the grain crush is. It's probably the #1 factor effecting efficiency.
Before I bought my own mill, I was getting my grains crushed at my LHBS. My efficiency was all over the place (40-72%) and I had a hard time predicting any values consistently at all. Once I started crushing my own grains, everything stabilized out and my efficiency when up to about 78-80%.

After I've been watching my volumes a little closer, controlling my boil rate and fiddling with the mash pH, I'm hitting 84-85% consistently (except for my very dark porters and stouts. I'm still in the 70's on those.)

As far as your batch sparge goes, you want to heat the sparge water high enough to raise the mash temp. to 168-170. Stir thoroughly, vorlauf and drain. You don't really need to let it set for 20 min. I usually just go about 10 min. to let the grains set up again.
The speed at which you drain the mash does not make a difference (that I'm aware of). This is the one of the benefits of batch sparging over fly sparging. Batch sparging is faster. Open 'er up and let 'er drain.

Hope this helps.
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Postby Suthrncomfrt1884 » Mon Jul 27, 2009 10:38 pm

The grains I bought were actually crushed by the company who supplies grain to my LHBS. The crush is always great when it comes like this. I have to pay an extra few cents per pound, but it's worth it. When I've used the mill at the LHBS, it gives me a horrible crush, so I stopped using it.

Anyway...I think the slower sparge may have actually helped. I brought my mash up to 169.8 degrees with the sparge... almost perfect. I let it settle for 20 minutes just to be safe. I sparged very slowly. Took about 32 minutes to collect 6.5 gallons. Boiled for one hour and ended up with 5.5 gallons. My pre-boil efficiency was coming out at 30.6 ppg. I think that yielded me around 80% efficiency. But after the boil, beertools is calculating my efficiency at 76.6%. Not too shabby concidering I made at least a 15% jump over my past batches.

Good brew day.
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Postby Legman » Tue Jul 28, 2009 5:20 am

Hey good deal man. :)
If you can repeat that on a consistent basis, you're on to something.

The grains I bought were actually crushed by the company who supplies grain to my LHBS. The crush is always great when it comes like this. I have to pay an extra few cents per pound, but it's worth it. When I've used the mill at the LHBS, it gives me a horrible crush, so I stopped using it.

You should think about buying your own grain mill. You'll have control of the crush and since you're already paying someone to crush it for you, it will pay for itself.
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efficiency

Postby slothrob » Tue Jul 28, 2009 6:34 am

Suthrncomfrt1884 wrote:Anyway...I think the slower sparge may have actually helped. I brought my mash up to 169.8 degrees with the sparge... almost perfect. I let it settle for 20 minutes just to be safe. I sparged very slowly. Took about 32 minutes to collect 6.5 gallons. Boiled for one hour and ended up with 5.5 gallons. My pre-boil efficiency was coming out at 30.6 ppg. I think that yielded me around 80% efficiency. But after the boil, beertools is calculating my efficiency at 76.6%.

When you get efficiency gains from a sparge rest and/or slow batch sparge runnoff, it probably means that you weren't fully converted at the end of your mash rest. Allowing the grain to sit longer allows conversion to complete.

You can test this by testing the gravity of the wort from your sacc rest and calculating the total points based on your strike water volume.. This value, the conversion efficiency, should be high, like 95-100%. If it's lower, you should extend the rest or bump the temperature up to 155-162°F to speed up conversion without increasing the fermentability further, if that's your preference.

A side note, mash efficiency can't change from before the boil to after the boil, since only water is lost during the boil. Is the post-boil value lower because of wort lost due to transferring out of the kettle? You shouldn't include those losses in mash efficiency considerations. That's part of Brewhouse Efficiency, which is another issue.
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Postby Suthrncomfrt1884 » Tue Jul 28, 2009 8:16 am

I poured my wort through a strainer into the fermenter, so I wouldn't this the little bit trapped in the hop debris would make a huge difference.

I also though efficiency should be the same. I have a horrible hydrometer though and intend on buying something nicer. Mine doesn't like to read well when it's going into 160-170 degree water. I think that may be why I had the difference between pre and post boil.
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Postby slothrob » Tue Jul 28, 2009 5:59 pm

Suthrncomfrt1884 wrote:I poured my wort through a strainer into the fermenter, so I wouldn't this the little bit trapped in the hop debris would make a huge difference.

I also though efficiency should be the same. I have a horrible hydrometer though and intend on buying something nicer. Mine doesn't like to read well when it's going into 160-170 degree water. I think that may be why I had the difference between pre and post boil.

I measure volume in the kettle and ignore the hop volume, which might be cheating a bit.

I have the same problem with my hydrometer and high temperatures. I find that I need to cool the wort down to at least 100-110F to get a good reading (even after correcting for the temperature). I'm not sure why this is the case, but it seems to be the way it is.
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Re: efficiency

Postby slothrob » Tue Jul 28, 2009 6:11 pm

slothrob wrote:You can test conversion efficiency by testing the gravity of the wort from your sacc rest and calculating the total points based on your strike water volume.. This value, the conversion efficiency, should be high, like 95-100%.

Someone pointed out that I left out the contribution of the dissolved sugar to the wort volume. Conversion Efficiency is calculated from the First Runnings Gravity and the total volume in the mash.

The total volume in the mash can be calculated with this formula, to a tenth of a gallon:

S x (1 + A + A^2)

S = strike volume in gallons
A = additional volume per gallon correction factor = (gravity) x (0.078 gal/pound of sugar) / (46 points per pound of sugar) = gravity x 0.0017.
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Re: efficiency

Postby Suthrncomfrt1884 » Tue Jul 28, 2009 7:38 pm

slothrob wrote:Someone pointed out that I left out the contribution of the dissolved sugar to the wort volume. Conversion Efficiency is calculated from the First Runnings Gravity and the total volume in the mash.

The total volume in the mash can be calculated with this formula, to a tenth of a gallon:

S x (1 + A + A^2)

S = strike volume in gallons
A = additional volume per gallon correction factor = (gravity) x (0.078 gal/pound of sugar) / (46 points per pound of sugar) = gravity x 0.0017.


Maybe that's a different way of explaining this... not sure. I figure my efficiency by taking the preboil gravity reading and multiplying it by how many gallons of water I collected. So, yesterday my gravity was 1.046. I multiplied by 6 gallons and got 276. I then divide that number by the amount of grain used in lbs. So 276 divided by 9 = 30.66.

Not sure if this is right or now...that's the way I learned though.
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Efficiency

Postby slothrob » Tue Jul 28, 2009 8:14 pm

Efficiency is a lot of different things.
The one we care about the most is mash efficiency, which your formula is getting at. There are a number of ways to get that number, but basically it is volume in the kettle times gravity divided by total points available from your grain bill. I use a slightly different formula than you but you can get the same information from them:
(gravity x volume) ÷ (#s of grain x 36) x 100 = mash efficiency
The 36 is the expected points per pound per gallon expected from the grain, which can vary, but 36 is typical.

Mash efficiency, however, is made of two things: Conversion Efficiency, or how much of the starch gets converted to sugar, and Lauter Efficiency, or how well you get that sugar out of the mash tun.

If you measure the gravity of the first runnings alone, and use my formula to calculate the total volume of liquid in your mash tun, you can get the total points of converted sugar and calculate your conversion efficiency.

Then, if you use your formula to calculate Mash Efficiency, you can use that and the Conversion Efficiency to determine your Lauter Efficiency. All of these numbers, considered together will tell you what aspect of your mash you need to work on to increase your efficiency.
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Postby Suthrncomfrt1884 » Tue Jul 28, 2009 9:24 pm

Sounds good. I'll test it all out on my next batch. I think I'll be brewing another this weekend. Thanks for the help.
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efficiency

Postby slothrob » Tue Jul 28, 2009 10:22 pm

Good luck!

Just deal with each issue as you isolate it, and you'll get your efficiency up.

While waiting to check your conversion efficiency, you can measure your dead volume by putting some water in your tun and seeing how much remains undrainable. This is a weak link in lauter efficiency that can be fixed with good tun design.
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Postby Suthrncomfrt1884 » Tue Jul 28, 2009 11:31 pm

I beat you to the punch. Just measured tonight.
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Postby dougms46 » Thu Dec 24, 2009 9:16 am

slothrob: would this calculation work for cool wort before yeast is added?
My last batch I used 47 lbs. of grain and collected 17 gal. then boiled
down to 16gal. My fermenter holds 15gal. and at that point the wort weighed
in at 1.072 . So my efficiency seemed higher than I would have expected!
Unless I did the formula wrong
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efficiency

Postby slothrob » Thu Dec 24, 2009 5:21 pm

The mash efficiency formula? Sure. It doesn't matter if the measurements are taken before or after the boil, as long as you use the gravity and volume from before the boil or the gravity and the volume from after the boil.

I come up with about 68% mash efficiency. That's pretty respectable for such a big batch.
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