Whay am I missing OG by so much?

[Iceman6409]

First off I am a BIAB brewer but I don't think that makes a difference as I have made a handful of BIAB beers and been very close to OG. However the last 2-3 have been way off. Today I made Yoopers Haus Pale Ale. Mashed at 155 and it ended up at about 151-152 for some reason. 6.5 gallons pre-boil. I did not take pre-boil reading. Everything else seemed to go fine in the boil. Chilled with wort chiller and took the reading at 70 degrees. I did do the reading in the kettle this time. It showed 1.041.

What are some possible reasons this happened? Is there anything I can do fix it when I do brews in the future if it happens again?

 

[eadavis80]

How much volume did you end with? If you lose 1 gallon / hour (pretty average) you might have ended with 5.5 gallons in the fermenter, thus the lower OG. I aim for 6 gallons pre-boil to net 5. Also, were these grains crushed the same way as your other batches that had a more desireable OG? Double crushed grains help BIAB, so I wondered if there was a difference in your grains.

 

[pricelessbrewing]

Didn't provide enough info to determine what the issue is.

Could be volume, as they said above.

Could be conversion efficiency, which requires first running gravity reading (if you sparge). If you don't sparge, then we can do the math and work this out from the preboil or postboil.

Could be natural variation in mash efficiency as a function of changing grain bills.

Could be different lauter efficiency not being accounted for. This is particularly true for big brews, and sparging setups

 

[Iceman6409]

Ok here is what I remember. Recipe called for 10.5lbs grain. I mashed 3.5 gallons water at 165 to settle at 155 for one hours. End mash temp was around 151-152. That part is a true mystery to me in itself as I had this in a 5 gallon round cooler AND I put it right in front of me heat vent. Anyways I drew out 2.75 gals. Mashed with another 4.5 to get a total pre boil volume of 6.5 gals. I measure my liquids religiously. Boiled for 60 minutes. Made my hop additions on schedule. Chilled with my wort chiller right at flame out. Got down to 70. Put hydrometer in kettle and tool reading. I thought initially it was right on 1.051 so I looked again and it said 1.041, for sure. I crushed grains only once at LHBS. I have done twice before but this time I was on a bit of a time schedule.

 

[Stillraining]

I think you found your own answer..

 

[beernutz]

Ok here is what I remember. Recipe called for 10.5lbs grain. I mashed 3.5 gallons water at 165 to settle at 155 for one hours. End mash temp was around 151-152. That part is a true mystery to me in itself as I had this in a 5 gallon round cooler AND I put it right in front of me heat vent. Anyways I drew out 2.75 gals. Mashed with another 4.5 to get a total pre boil volume of 6.5 gals. I measure my liquids religiously. Boiled for 60 minutes. Made my hop additions on schedule. Chilled with my wort chiller right at flame out. Got down to 70. Put hydrometer in kettle and tool reading. I thought initially it was right on 1.051 so I looked again and it said 1.041, for sure. I crushed grains only once at LHBS. I have done twice before but this time I was on a bit of a time schedule.

I am not a BIABer but is this another mash or a sparge/rince?

 

[Iceman6409]

I mashed at 155 for one hour. End temp was 152. I drew out 2.75 gallons wort. Sparged with 4.5 gallons to get a pre-boil volume of 6.50 gallons to get dow to 5.25 after boil.

 

[pricelessbrewing]

How did you sparge though? Did you stir it all together, pour it over? Use a sparge arm or something?

 

[Nagorg]

On crushing twice... seems to make a case for having your own mill. I've read many comments about improved efficiency when using your own mill that you can calibrate at will.
I'm considering a mill myself for that very reason.

 

[Iceman6409]

For sparge I put bag and grain back in cooler, dmped water in, stirred and waited 10 minutes and drained

 

[harry_the_face]

First I would text your thermometer in boiling water and make sure it is accurate. I had had a few batches off for this reason and in a wet environment they get off a lot.

Second the reason your mash temp dropped so much is because you put it in front of your heater vent. No heater outs out air at or above 155 deg unless it is a jet heater you use in a garage with with an open flame. Most heaters don't put out air hotter than 90 deg.

 

[doug293cz]

I mashed at 155 for one hour. End temp was 152. I drew out 2.75 gallons wort. Sparged with 4.5 gallons to get a pre-boil volume of 6.50 gallons to get dow to 5.25 after boil.

Your volumes don't add up. Since the grain is saturated when sparge water is added, you should recover the total volume of sparge water. Your pre-boil volume should have been 2.75 + 4.5 = 7.25 gal. You're missing 3/4 of a gal somewhere.

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