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General Category => All Grain Brewing => Topic started by: bobjohnson on April 13, 2011, 06:06:29 PM

Title: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: bobjohnson on April 13, 2011, 06:06:29 PM
90% of the time I do 5 gal batches and batch sparge using a 52qrt extreme cooler as mash tun and a keggle to boil.    But, my last to beers were 10 gal batches on this equipment of moderate (1.050 - 1.060) OG's. 

When I do my 5 gal batches, I am consistantly in the 70 % range (+- couple percent.)    On these last 2 each 10 gal batches, I came in between 80 % and 85 %.

I crush my malt myself, and did not change anything regarding that.   I believe my volume measurements are accurate.   

I don't stress out about this too much.  If anything, would prefer to expect higher gravity and get lower, so I can adjust with extract if needed.   On a 10 gal batch, I didn't want to add water before the boil to dilute due to the limited space in the kettle, so I just went with it.

Has anyone else seen an improvement in efficiency by just doing larger volumes?

Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: weithman5 on April 13, 2011, 06:14:44 PM
if you use the same tun in both cases the amount of sugar lost in dead space will likely be the same no matter if it is a 1 gallon, 5, or 10 gallon batch.  this makes up a larger percentage of total sugar in a small batch compared to a larger batch.  thus a drop in efficiency.  i don't know if this accounts for all of your numbers but it may represent a substantial part.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: dmtaylor on April 13, 2011, 07:30:01 PM
weithman5 has an excellent point, and might be the biggest factor for 10-gallon batches or for certain systems.  But for me, I actually find the opposite to be true -- I get better efficiency with SMALLER batches, based on a completely different effect -- Whether I'm making 2.5 gallons or 5 gallons, I am always boiling off a little over 1 gallon per hour.  Boiloff rate is a constant assuming you use the same kettle for making both size batches.  So as an example, percentage-wise, I am squeezing a lot more sugars out of my grain when I collect a pre-boil volume of 3.5 gallons of sweet wort to end up with 2.5 gallons post-boil, compared to when I collect 6 gallons to end up with 5 gallons after the boil.  In both cases, I'll boil off a gallon, but percentage-wise, I know that I have to sparge a heck of a lot more on the smaller batches to get the final volume that I want.  The result?  On 2.5-gallon batches, I can easily hit 90% efficiency every time, boom boom boom.  On 3.5-gallon batches (which yes I have done on occasion), it's more in the mid 80s.  On 5-gallon batches, maybe the low 80s.  It makes a difference, at least to a point.  But eventually the effect might wear off with bigger batch sizes, or even out with the dead space effect.  I've never made a 10-gallon batch, don't have the equipment for it, but it might make for an interesting experiment for someone else.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: Will's Swill on April 14, 2011, 12:16:32 AM
I'd buy either of these two as possible contributors and I'll throw out another one, though perhaps it's less likely.  Given that you're using the same mash tun for both size batches, is your temperature less stable on the small batch?  The larger mash would provide more thermal mass and may lose less heat in a given tun over a given period of time.  Perhaps you're dropping to a suboptimal conversion temperature?  I use different size tuns for different size batches, but that's mainly for ease of use.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: ccarlson on April 14, 2011, 01:15:38 AM
Quote
If anything, would prefer to expect higher gravity and get lower, so I can adjust with extract if needed. 

I can't see why you'd prefer lower efficiency. Just adjust your hops and dilute it with water, What's wrong with more beer?

If your fermenter is too small, then take some of the wort and use it for starters next time around. Either way it's win-win.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: jwaldner on April 14, 2011, 01:37:29 AM
I experience the same thing.  When I do a 5.25 gallon batch I get about 50% efficiency on my system (using a 26-gal stainless pot).  However, when I do a 10.5 gallon batch I get about 76% efficiency.  I've also noticed that if I do a stir about every 15 minutes I get better efficiency.

I think it has something to do with the depth of the grain bed but haven't researched it.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: Hokerer on April 14, 2011, 02:16:23 PM
I experience the same thing.  When I do a 5.25 gallon batch I get about 50% efficiency on my system (using a 26-gal stainless pot).  However, when I do a 10.5 gallon batch I get about 76% efficiency. 

Wow, only getting 50% would have me seriously looking for problems.  That's pitiful :(
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: jwaldner on April 15, 2011, 02:43:39 AM
I experience the same thing.  When I do a 5.25 gallon batch I get about 50% efficiency on my system (using a 26-gal stainless pot).  However, when I do a 10.5 gallon batch I get about 76% efficiency. 

Wow, only getting 50% would have me seriously looking for problems.  That's pitiful :(

Sure is, but when I do the 10.5 batch of the same beer it jumps.  Since I'm using such large pots for my mash tun and kettle the only conclusion I draw it's due to the depth of the grain bed.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: tschmidlin on April 15, 2011, 02:44:54 AM
I experience the same thing.  When I do a 5.25 gallon batch I get about 50% efficiency on my system (using a 26-gal stainless pot).  However, when I do a 10.5 gallon batch I get about 76% efficiency. 

Wow, only getting 50% would have me seriously looking for problems.  That's pitiful :(

Sure is, but when I do the 10.5 batch of the same beer it jumps.  Since I'm using such large pots for my mash tun and kettle the only conclusion I draw it's due to the depth of the grain bed.
Are you batch sparging like the OP?
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: jwaldner on April 15, 2011, 01:23:59 PM
I experience the same thing.  When I do a 5.25 gallon batch I get about 50% efficiency on my system (using a 26-gal stainless pot).  However, when I do a 10.5 gallon batch I get about 76% efficiency. 

Wow, only getting 50% would have me seriously looking for problems.  That's pitiful :(

Sure is, but when I do the 10.5 batch of the same beer it jumps.  Since I'm using such large pots for my mash tun and kettle the only conclusion I draw it's due to the depth of the grain bed.
Are you batch sparging like the OP?
I'm fly sparging.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: tschmidlin on April 15, 2011, 03:55:34 PM
Then I agree, bed depth is probably the problem.  You might think about batch sparging for the smaller batches, just for fun.  It can't get much worse than 50%, can it? 
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: jwaldner on April 15, 2011, 11:52:29 PM
Thanks Tom, I'll give it a shot. I've also considered just using a smaller mash tun and see if that works any better next time.

Cheers!
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: Will's Swill on April 16, 2011, 12:38:26 AM
Then I agree, bed depth is probably the problem. 

Bed depth impacts efficiency?
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: jwaldner on April 16, 2011, 02:40:16 AM
Then I agree, bed depth is probably the problem. 

Bed depth impacts efficiency?

It was my understanding that if the mash bed wasn't deep enough that when sparging the water would move through to quickly and not extract the sugars as efficiently.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: tschmidlin on April 16, 2011, 05:20:19 AM
Then I agree, bed depth is probably the problem. 

Bed depth impacts efficiency?
Under the right (or should I say wrong?) conditions, bed depth can affect efficiency.  You can mitigate it by having enough water over the bed, running off slower, or probably by batch sparging.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: denny on April 16, 2011, 03:34:08 PM
Then I agree, bed depth is probably the problem. 

Bed depth impacts efficiency?

In fly sparging, yes.  In batch sparging, very little to not at all.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: Will's Swill on April 16, 2011, 05:39:46 PM

It was my understanding that if the mash bed wasn't deep enough that when sparging the water would move through to quickly and not extract the sugars as efficiently.

Huh.  But flow rate can be controlled, so I don't think this would be a problem.  I could maybe see that if you put the same amount of grist into two mash tuns, one that is wider than the other so that the grain bed depth is less, maybe the wider tun would have less efficiency since not as much sparge water flows past any particular grain.  Maybe.  I doubt it, but maybe.

On the other hand reducing the amount of grist in a particular tun would also reduce grain depth, like in the OP's case.  But that would mean that the sparge water flowing past any particular grain on the bottom of the tun would have a lower concentration of sugar, since it hasn't passed through as much grist.  I bet that would increase efficiency if anything.

I suspect the grain bed depth thing is one of those homebrewing urban legends like recirculating the mash until clear, trub removal, and CO2 blankets...  ;D
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: denny on April 16, 2011, 06:06:04 PM
Again, keep in mind that only applies if you fly sparge, not if you batch sparge.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: tschmidlin on April 16, 2011, 06:12:21 PM
I suspect the grain bed depth thing is one of those homebrewing urban legends like recirculating the mash until clear, trub removal, and CO2 blankets...  ;D
Test it ;)
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: Will's Swill on April 16, 2011, 06:17:32 PM
Indeed!  Whaddaya think, IPA vs. IIPA?  Or perhaps same beer, but different batch sizes?  Hmm, with the different batch sizes I could finally do that blow-off vs no blow-off side-by-side that I've been meaning to do...

I also bought some long matches to mess around with the CO2 and see if it stays put.  But not until after taxes. 

This *$(^(*# forum can really provide a lot of procrastination opportunity.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: tschmidlin on April 16, 2011, 06:41:46 PM
I think 5 gallons of pale ale and 10 gallons of IIPA, go for a big difference.  Same grist composition, mill setting, length of mash, etc.  The runoff speed is an interesting variable, do you run off at the same volume per time, or go for the same time for run off?

As for your match experiment, I doubt it will work.  It depends on how you do it, but keep in mind that there needs to be about 13%+ O2 in the air you're testing to maintain a flame.  I don't think anyone is saying that CO2 blankets are complete BS, there is some effect, especially if there isn't a lot of air currents.  But it's not rock solid like some people seem to think, and it will dissipate over time, if not from air currents then from diffusion.  If this didn't happen you'd suffocate in Death Valley.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: Will's Swill on May 31, 2011, 05:11:45 AM
OK, the results are in.  12# grist v. 6# grist for two IPAs that are otherwise identical.  1 qt/# strike water plus 3 qts for foundation water.  1.75 qt/# at 167F for fly sparging.  The mash tun used for both was an insulated 5 gallon bucket with a false bottom, so the bed depth was approximately halved by going from 12# to 6#, and the depth difference was bigger than if I had used my rectangular cooler.  Each mash was three hours at 145F with an additional infusion of .25 qt/# boiling water at the 2:15 mark (stirred to return back down to 145F - iodine test on both was positive at 2 hours; figured I mashed too thick so I added water to thin it down; each showed fully converted at the 2:45 mark - and I know iodine shouldn't be trusted, but oh well).  I used the same flow rate for each sparge.

12# grist - 81% efficiency to kettle
6# grist - 84% efficiency to kettle

While the smaller bed depth apparently had a slightly higher efficiency, the difference is small and could be due to measurement or process error, or the simplistic way I calculate efficiency (points * volume/extract potential).  An interesting data point is that I lost .21 gal/# to the grist in the 12# mash, but only .14 gal/# in the 6# mash.  That by itself could account for the difference (there's virtually no deadspace in the mash tun)

A highly non-scientific test, but there ya go.
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: richardt on May 31, 2011, 02:04:57 PM
...  It depends on how you do it, but keep in mind that there needs to be about 13%+ O2 in the air you're testing to maintain a flame.  I don't think anyone is saying that CO2 blankets are complete BS, there is some effect, especially if there isn't a lot of air currents.  But it's not rock solid like some people seem to think, and it will dissipate over time, if not from air currents then from diffusion.  If this didn't happen you'd suffocate in Death Valley.

In nature, while rare, CO2 blankets can and do exist.  And the results are quite deadly.
http://vulcan.wr.usgs.gov/Glossary/Lakes/description_volcanic_lakes_gas_release.html (http://vulcan.wr.usgs.gov/Glossary/Lakes/description_volcanic_lakes_gas_release.html)
http://volcanoes.usgs.gov/hazards/gas/index.php (http://volcanoes.usgs.gov/hazards/gas/index.php)

In homebrewing, CO2 blankets pose a great and invisible threat to homebrewers who brew in unventilated areas and/or in basements with propane burners. 
Be smart and brew outdoors and/or in well-ventilated areas.  Give that toxic gas somewhere to go.
CO2 in fermentation vats also can be lethal
http://www.brewsnews.com.au/2010/02/death-by-beer/ (http://www.brewsnews.com.au/2010/02/death-by-beer/)
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: tschmidlin on May 31, 2011, 04:10:51 PM
...  It depends on how you do it, but keep in mind that there needs to be about 13%+ O2 in the air you're testing to maintain a flame.  I don't think anyone is saying that CO2 blankets are complete BS, there is some effect, especially if there isn't a lot of air currents.  But it's not rock solid like some people seem to think, and it will dissipate over time, if not from air currents then from diffusion.  If this didn't happen you'd suffocate in Death Valley.

In nature, while rare, CO2 blankets can and do exist.  And the results are quite deadly.
http://vulcan.wr.usgs.gov/Glossary/Lakes/description_volcanic_lakes_gas_release.html (http://vulcan.wr.usgs.gov/Glossary/Lakes/description_volcanic_lakes_gas_release.html)
http://volcanoes.usgs.gov/hazards/gas/index.php (http://volcanoes.usgs.gov/hazards/gas/index.php)
I've heard about those instances, but this isn't the same.  You want 100% CO2 (really 0% O2) over your beer to protect it, but relatively low levels of CO2 in the air can cause health problems for people.  From your second link:
Quote
Air with 5% CO2 causes perceptible increased respiration; 6-10% results in shortness of breath, headaches, dizziness, sweating, and general restlessness; 10-15% causes impaired coordination and abrupt muscle contractions; 20-30% causes loss of consciousness and convulsions; over 30% can cause death



In homebrewing, CO2 blankets pose a great and invisible threat to homebrewers who brew in unventilated areas and/or in basements with propane burners. 
Be smart and brew outdoors and/or in well-ventilated areas.  Give that toxic gas somewhere to go.
CO2 in fermentation vats also can be lethal
http://www.brewsnews.com.au/2010/02/death-by-beer/ (http://www.brewsnews.com.au/2010/02/death-by-beer/)
There is a big difference in the amount of CO2 generated on a homebrew level compared to a commercial brewery.  I'm not saying there is no risk, but it is low risk.  I fermented 10 gallons in a closed bathroom recently, and whenever I went in there there was enough CO2 concentrated to burn my nostrils a little bit.  I wouldn't want to do more than that actively fermenting in a closed space.

Also, the larger danger from propane burners is carbon monoxide, CO.  CO binds very tightly to hemoglobin, much more so than O2.  There's more to it, but the end result is that your body doesn't get the oxygen it needs.  And that's bad. ;)
Title: Re: higher efficency w/ 10 gal batch than on a 5 gal ?
Post by: 52mgtd on June 05, 2011, 08:33:47 PM
yes, I suspect there's more mass to hold the heat.  I love doing 5 gal reciped & getting 9 gallons of wort!