[bobjohnson]

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?

[weithman5]

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.

[dmtaylor]

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.

[Will's Swill]

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.

[ccarlson]

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.

[jwaldner]

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.

[Hokerer]

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

[jwaldner]

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.

[tschmidlin]

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?

[jwaldner]

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.

[tschmidlin]

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? 

[jwaldner]

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!

[Will's Swill]

Then I agree, bed depth is probably the problem. 

Bed depth impacts efficiency?

[jwaldner]

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.

[tschmidlin]

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.