Another impossibly high efficiency

what's wrong with my efficiency calculations?
I pitched 15.5L of wort on top of 2L of yeast cake, from an ipa that finished at 1.011 using mangrove jacks british ale yeast.
Grainbill was 500g maris otter and 500g pale rye malt.
I measured the OG as 1.022. I'm attempting a low alcohol beer, inspired by basicbrewing's latest rye beers.
from my calculations, this has an efficiency of well over 100%

 

Just did a 2 point calibration on my hydrometer. I measured 20g of sucrose and disolved it in 180ml of 20*C water. should read 10*P or 1.040, which I got, exactly. 20*C tap water reads 1.001. So my hydrometer can't be too bad.

Anyone else experiencing this?

 

Show us your efficiency calculations and we'll tell you what's wrong with them.

 

well I've used brewtoad and brewersfriend to work out my efficiency, I'll try others if you can suggest any. Again, I used 500g of maris otter and 500g of rye, assuming ppg of 38 and 29, respectively. 15.5L of wort after the boil, 2L of yeast cake (should that affect the reading? it would lower it if anything, I would have thought) What more do you need? There's clearly something very strange going on here, in a good way I guess. As far as I know, 115% efficiency is impossible.

 

briess and cmc and fawcett all show rye at 80+% dry yield so potential 1.037 as a minimum. You used a large quantity of water for a tiny amount of grain so your going to get max efficiency.
http://www.brewingwithbriess.com/Assets/PDFs/Briess_PISB_RyeMalt.pdf
http://www.countrymaltgroup.com/canadamalting.asp
http://www.countrymaltgroup.com/fawcettmalting.asp

And the malt analysis that shows potential is from a small sample of a large batch, so it can vary.

 

That would just about explain it, if the rye yeald is that high. I might have to assume a brewhouse efficiency of 100% in future, unless I can track down the individual maltsters.

 

Another point to consider; most published malt data is from averages of the product. Different grain growing seasons can and do produce grains with different amounts of sugar. I suspect the maltsters do congress mashes on each season and adjust the published data towards the low end of the range. Any way you can get a malt analysis of the specific grains you used? It might be on the sack. Anyone that purchases grain by the sack want to jump in here?

 

I'm a pretty new to all grain but I think the problem is that it sounds as is you are doing your efficiency calculations after the boil. Check the gravity of your collected wort before the boil.

 

just double checking the numbers...

2.2 lbs grains at 37ppg

2.2 * 37 = 81
81 points / 4 gallons = 20 max ppg
22 points measured gravity / 20 ppg max = 1.1

so i'm also seieng an efficiency of 110%+ using ppg standards

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how did you draw your sample?

 

I've asked my hb shop about who the maltsters are, they haven't got back to me yet. another thought that I've had is that I bought bags of milled grain, I might have got more of the inner bit and less of the husk in the bag.

 

that all sounds like a stretch to me

what was the temperature of the wort when you took the reading? was this a full volume boil?

 

I take every reading at 20*C. it was a full volume boil.

 

Are you looking to compare brewhouse efficiency or pre-boil?

Ive always been under the impression that when most people here talk efficiency they mean pre-boil. Or at least I do lol.

How much water did you boil off? I know when I do small batches I get a higher % of boil off than usual, and that if I didn't plan for it my breehouse efficiency goes way up...but I have less beer.

 

I just realized it was a full size batch. Damn metric system lol

 

how did you measure the volume of wort into the fermenter?

in other words, are you sure it's 15.5 liters?

 

I measure OG after the boil for working out efficiency. I don't think it should matter if you measure the gravity before or after the boil when you're working out efficiency, as long as you use the volume as it was when you took the reading. volume will drop as gravity points increase when you boil.
Not sure If anyone's answered this yet, but does pitching on a yeast cake make a difference to the gravity? If the previous beer finished at 1.011, and I measured gravity after pitching, does that mean that the wort gravity could have been higher? or is that relevant at all?

 

...also, I went by the graduations on the side of my coopers fermentor for the volume, they couldn't be wrong, could they?

 

whether you measure pre or post boil doesn't matter so long as your volume is correct.

regarding the 2L of "yeast cake"

if you add two liters of 1.011 beer to 15.5 liters of 1.022 wort, that would measurably lower the gravity, i think by 11% in this case because 2 / (15.5+2) = 0.11. however the 2L would be reduced by whatever portion of that volume was yeast and trub solids. if we assume it was 1L solids and 1L water, then that would have lowered the gravity by 1 / (15.5+1) = 0.06 or 6%.

if it is 2L of solids, which is not very likely, then it would have no effect on the gravity.

 

Let's work in points per kilogram per liter.

total_gravity_points = (1.022 - 1.0) x 1,000 x 15.5 / 1 = 341 points per kilogram per liter

While not out of the question, I personally have never received a malt analysis sheet with a hot water extract (HWE) rating of 341 points per kilogram per liter (more in the 300 to 315 range) from a British maltster or a dry basis, fine grind (DBFG) extract rating of 88.8% from a European or American maltster, which leads me to believe that something is out of calibration. You need to verify the accuracy of the graduations on your fermentation vessel as well as the accuracy of your scale when weighing mass amounts less than or equal to one kilogram.

For those of us who still work with English units of measure, 341 points per kilogram per liter equates to 341 / 8.35 = 40.84 points per pound per gallon, which is kind of unbelievable.

Note: The figure 8.35 was derived from the fact that there are 2.20462 pounds in a kilogram and 3.78541 liters in a gallon.

 

great post EAZ. i agree - i think it is likely that either the volume or grain weight is inaccurate.

 

I will test my scales with a measured volume of water. I will have to measure the fermenter with 1L jugs, though it will allow for cumulative error.

I am starting to think that this has to do with buying pre milled grain. when you shake a bag of pre milled grain, you will see the hulls rise to the top and the endosperm fall to the bottom. My bags may have more endosperm than hull, I'm assuming that the endosperm is the starchy bit.