Gravity problem

[Bruinpilot]

I was looking for some help. I am brewing my 3rd batch, a hefeweizen. I constructed the recipe on beersmith2. It is all grain. I wanted to mash at 153. I mashed for 90 minutes. I opened my mash tun at the end of 90 minutes and I found the thermometer at 156. So a little warm. Beer smith predicted a preboil gravity of 1.034. I measured a corrected hydrometer reading of 1.033. I boiled one hour and hit the target boil off. I may have had a little extra, so a little dilution was possible, but I boiled off over 2 gallons, from 8.3 to about 6.something. However I took a post boil hydrometer reading and got only 1.038. Beer smith predicted 1.047 based on my grain bill, equipment, etc... I am just perplexed by the low gravity reading. It was the first flow out of the keggle. I don't know if this could have made a difference and I didn't take subsequent readings... Anyways I was just a little concerned about the lower gravity than expected. Thanks for the input.


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[Double_D]

I'm guessing beersmith expected you to boil down to 5.5 gal or somewhere in that neighborhood. It's the only guess I can come up with.

 

[rlonardo]

Sounds like a measurement error. I'm calculating that if you boiled off 2 gallons you should be sitting around 1.044.


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[Yooper]

If you used a hydrometer for your preboil reading, that sample has to be cooled to under about 100 degrees, and then adjustments can be made. Any reading over 100 degrees or so is notoriously in accurate.

If you took the preboil reading, was the volume 6+ gallons at that time? I'm unclear what the actual volume and preboil reading was. If that was the SG of the first runnings, did you sparge and add that to the brewpot? I'm just trying to picture your procedure to see if we can troubleshoot where the error is.

 

[Bruinpilot]

The preboil reading was taken after combining all of my runnings. I batch sparged in three steps and collected approximately 8.2 gallons. The temperature at the time I took that reading was approximately 155. The final reading was taken after boiling down to about 6.4 gallons at a temp of about 78.

It has been in my fermentation chamber now about 36 hours and it bubbling furiously even at 64 degrees. I'm glad I put on a blow off tube... I'm just bummed I missed my gravity. Except for this issue, this was my smoothest batch to date as far as hitting snags goes...


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[Bruinpilot]

Rlonardo, I hope you are right because that puts me right about where I wanted to be! Hoping it was just operator error!


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