I have a straight braided line as a manifold in my mash tun and usually batch sparge. I recently used this setup and did a fly sparge and got horrible efficiency. Is it because of my manifold? I would think fly would give better results then batch on a given tun design, but maybe that’s not the case? Maybe I’m just barking up the wrong tree?
Yeah, a straight braided line will promote channeling, allowing the water to “drill down” in one spot and only extract the sugars from that one location, leading to lowered efficiency. If you want to fly sparge, you need a more evenly distributed lautering system. One of the great things about batch sparging is that it eliminates lauter design as a variable in efficiency. FWIW, fly sparging is not necessarily more efficient than batch sparging.
Nope, but it’s definitely going to attract more women. 
(Ok, that’s my bad pun for the day)
Hi, thanks for the reply.
I understand the principal of channeling and good manifold design for maximal efficiency, but why would batch sparging yield higher efficiency than fly sparging using the same “poor” manifold design? Wouldn’t I get the same channeling no matter which way I sparged?
Channeling doesn’t matter when batch sparging since the runoff is homogeneous. You get the same concentration of sugars with batch sparging in a single draining of the tun from first drop to last. What is of upmost importance with batch sparging is crush. If one has a substandard crush then efficiency will be lower. With fly sparging the most important aspect IMO is mash tun manifold followed by crush.
You might get the same channeling but with batch it doesn’t really matter. When you fly sparge, if all of your sparge water is “channeling”, then it never actually rinses the sugars out of that portion of the grist that it doesn’t touch. With batch, since you’re going to drain all of the water, you’ll drain (and rinse) the water from the non-channeled areas of the grist too.
Ok, that makes sense (I think. ;-).
However, it seems that a better manifold design would benefit both batch and fly sparging alike. Right?
Not necessarily for efficiency but maybe for run-off speed.
What matters in batch sparging more than in fly sparging is the amount of wort that is left in the MLT after each run-off. The more you leave behind the worse your efficiency will be since you leave more extract behind. Most of it will be caused by grain absorption and you can’t do much about it unless you squeeze the grain. But some may be caused by dead spaces that you cannot drain fully. That might be the case if your pick-up is above the MLT floor.
Here are a few batch lauter tun designs. A and B are false bottoms. C - E are braids or pipe manifolds:
A is best since you don’t have any dead space. E is worst if you stop the run-off as soon as bubbles appear. The case E may happen when the braid floats up.
But don’t fret out about it either. If the dead space contributes to less than a pint additional wort absorption it won’t make much difference. And in the end, batch sparging lauter efficiency lost is good for the beer since it keeps you from oversparging.
Fly sparging is different because of the channeling problem. There you can have low efficiency and still extract excessive tannins in the channel that formed. And if you don’t drain all the wort either you may never give the extract rich wort outside the channels a chance to “fall” into the channel and towards the manifold.
John Palmer did a lot of work on evaluating manifold designs for fly sparging and he dedicated a chapter in How To Brew to that. I did work on evaluating what matters for batch sparging (Batch Sparging Analysis - German brewing and more) and for what it’s worth you could batch sparge through a hole in the bottom of a bucket and it can still give you 80+ % efficiency for most beers. But it may take so long that the wort will sour before you are done.
Kai
So long as you can fully drain the tun, then the efficiency of your batch sparge is what it is. The only way you can lower it is by not completely draining the tun. What that says, in a nutshell, is you could theoretically find the lowest point of a tun and drain from that point. So a SS scrubbie covering that point would work - IF - it didn’t suck everything to that point and create a very slow flow - stuck mash. As was pointed out, you may speed the flow using a manifold or other method.
Kai,
D looks like the best braid technique. A Colman extreme 70 qt happens to be that profile.
Yes, that is correct. But keep in mind that lautering is not necessarily the best place to chase efficiency. If you are batch sparging and are seeing poor efficiency it is most likely due to incomplete conversion of the mash. The beauty of batch sparging is that its efficiency is not determined by dynamic difficult to control factors but only by static parameters like: wort let in the tun after run-off, number of run-offs and size of run-offs.
Fly sparging doesn’t have the theoretical efficiency limits of batch sparging, which are actually well in the 80s for most beers, but takes more skill and better equipment to be done right. It’s not as easily modeled as batch sparging. John took a stab at it in his book and I assume that there is much more data out there since big brewhouse manufacturers are concerned about that. They want their mash tuns to lauter as efficiently as possible.
Here is a little piece of information that I found a while back. Did you know that the swan-neck design seen on the faucets feeding old lauter grants are there to reduce suction on the grain bed? They are designed such that the opening of the faucet will be at the same level as the false bottom. As a result the wort that is below the false bottom and in the pipes leading to the grant cannot suck on the grain bed since it has to travel up the swan-neck where it looses all that energy. Modern tun designs monitor the pressure in each of these drain pipes and use that to regulate the pump speed as well as the cut depth of the rakes. The latter is also controlled by the clarity of the wort.
Yes, that is true. But don’t expect big gains from that difference. Maybe 1-2% would be my guess.
You can check for dead spaces and in efficiencies by calculating the grain absorption A after draining completely:
A = (total water volume used – temp corrected wort volume collected) / grist weight.
It is generally between 0.1 – 0.12 gal/lb. If you’re in that ball park there is not much you can improve. I have had a few cases where the grain retained more and I don’t exactly know why.
Note that A is what I call apparent grain absorption. The true grain absorption is higher since dissolved sugars also contribute to wort volume. But you only have to consider that if you need to know the actual volume left in the grain and not just what appears to be left in the grain. Here is some info on that: True vs. Apparent Grain Absorption
Kai
Thanks Kaiser for putting so much thought and effort into documenting brewing processes and providing a resource for those of us who can’t reference the German texts.
So, if I were to compare Batch to Fly sparging, I come up with the following:
-
Assuming a simple tun manifold with no dead space (Figure D), batch sparging can result in higher efficiency than fly sparging.
-
Assuming a false bottom with no dead space (Figure A), fly sparging will always yield better efficiency than batch sparging.
Is that correct?
Brian
Nope, not necessarily…at least not in my experience. There are other variables involved.
Yes. Even with dead space batch sparging can give higher efficiency. Important here is “can” which makes the statement fuzzy again.
No. And that is b/c you used “always”. When we compare efficiencies between the two we have to make sure we talk only about lauter efficiency. This is the efficiency with which soluble extract created in the mash is transferred into the boil kettle. You can make the statement though that the lauter efficiency of a perfect fly sparge (i.e. all wort concentration gradients are always pointing downward) will always be equal or better than a batch sparge (including no sparge). I had to use complicated language about concentration gradients to make that statement. “all wort concentration gradients are always pointing downward” essentially means that there is no channeling and no pockets that don’t get sparged.
In practice these two conditions: same level of mash conversion and completely even draining are not necessarily given and explain why there are many cases where batch sparging outperforms fly sparging in efficiency into the kettle. One controversial statement I have made in the past is this:
“Because there is no concern about channelling in batch sparging batch spargers might be able to mill their grist finer which may give them a more complete conversion in the mash. This additional mash conversion can lead to a greater efficiency into the kettle even if the actual lauter efficiency of the batch sparge is lower than that of the fly sparge”
And I’m standing to this even though it is easily misinterpreted and the becomes rather volitile fuel for the batch vs. fly debate. BTW, I’m so glad that we are over that and are now able to look at both thechniques with a more objective eye.
Kai
Kai,
I believe that by agitating the sparge one may acheive a better lautering efficiency. The only concern would be allowing fines to get into the kettle. If the trapped sugars (in solution) inside the grains were able to be mechanically extracted, one would acheive better efficiency. That’s assuming there is a significant amount of available sugars to extract which I believe to be true.
I don’t think that there are actually a lot of sugars trapped inside the grain. When I mean indide the grain I mean inside the grits. The mash gives enough time for those sugars to leach into the mash liquid. A fact that can be verified by testing the mash gravity. Once that is done it is all about whashing the sugar rich wort off the outside of the pieces that are the spent grain. There might be some diffusion happening from inside the grits into the sparge water but I deem that effect to be minimal. If it was true that a significant amount of sugar has to be extracted from the grits during the spare the rest time during batch sparges would matter.
Agitation during mash helps by providing some mechanical force that helps distibute enzymes, product and substrate. It helps during lautering b/c it breaks up channels that may have formed.
Kai
For instance…stirring and/or some other mechanical means during the mash would facilitate the transport of sugar into solution. This action would make for a more homogenous wort which would enable or encourage more gelatinization thereby enhancing lautering efficieny.
Getting more starch gelatenized should affect conversion efficiency but not so much lauter efficiency. The latter assumes that conversion has stopped and that there is no additional creation of soluble sugars during the lauter. An assumption that may not always be true and might be the explanation why some brewers see an impact of the sparge water temp on their efficiency.
Kai
Ok, so can I revise my conclusions as follows?
-
The lauter efficiency of a perfect fly sparge will always be equal to or greater than a perfect batch sparge for a perfectly designed lauter tun (such as Figure A.)
-
The lauter efficiency of a perfect fly sparge will be negatively impacted by a sub-optimal lauter tun design (such as Figure D) such that batch sparging may provide higher lauter efficiency.
On the subject of stirring, would stirring during lautering nulify the negative effects of a sub-optimal lauter tun design when fly sparging such that lauter efficiency of fly sparging again exceeds that of batch sparging?
Brian
Some breweries actually use a plate and frame filter to “squeeze” out the mash to get every last drop of liquid and the highest possible yield.
Here is said beast at Rodenbach