Odd gravity readings on new system

[pretzelb]

I'm not the best at keeping track of the numbers but I do a decent job but I can't seem to figure out what is going on with my new system. At first I suspected my refractometer but I started double checking with my hydrometer and I don't understand why my gravity readings are off after boil. Here is a sample from the last brew.


Start 16g @ 15" height
Boil Start 14.45g @ 13.5" height - temp 207 - temp adjusted 13.87g - 1042
Boil End 12.58g @ 11.75" height - temp 207 - temp adjusted 12.07g - 1047

I boiled about 1.8 gallons but my gravity only went from 1042 to 1047. I've trusted both pieces of equipment before but now I'm wondering if I need a third piece to verify the other two. Any ideas of what I might be doing wrong?

 

[billl]

Not sure what you think the problem is. 42 x 13.87 / 12.58 = 48 or 1.048. You are measuring 1.047. That's about as close as you can get.

 

[doug293cz]

Not sure what you think the problem is. 42 x 13.87 / 12.58 = 48 or 1.048. You are measuring 1.047. That's about as close as you can get.

You can't use one temp corrected volume and the other uncorrected. Either use both uncorrected (since they were measured at the same temp), or use both corrected volumes. Using the corrected volumes, the OG should have been:

1 + 0.042 * 13.87 / 12.07 = 1.048​

But somehow you got the right OG (and conclusion) even with your math mistakes (the equation you show gives an OG of 1.046.)

Brew on

 

[billl]

Sorry - typo. Typed 12.58 on the screen and 12.07 in the calculator.

Projected OG is 1.048 +/- whatever margin of error is in the original measurements. Certainly more than 0.001.

 

[1MadScientist]

I'm not the best at keeping track of the numbers but I do a decent job but I can't seem to figure out what is going on with my new system. At first I suspected my refractometer but I started double checking with my hydrometer and I don't understand why my gravity readings are off after boil. Here is a sample from the last brew.


Start 16g @ 15" height
Boil Start 14.45g @ 13.5" height - temp 207 - temp adjusted 13.87g - 1042
Boil End 12.58g @ 11.75" height - temp 207 - temp adjusted 12.07g - 1047

I boiled about 1.8 gallons but my gravity only went from 1042 to 1047. I've trusted both pieces of equipment before but now I'm wondering if I need a third piece to verify the other two. Any ideas of what I might be doing wrong?

Very nice tight sets of numbers With the two at boil volumes there is no need to adjust temperatures.

14.45 x 42
12.58 x 47

 

[pretzelb]

Maybe Beersmith is throwing me off, but it seemed to work for me in the past. Entering this into BS it tells me to expect 1050 for the OG. The estimate for evaporation matches so I'm not sure where the difference is coming from.

Is there a "more" accurate way to measure gravity for pre-boil? I will cool my sample enough to not break my hydrometer, but not all the way to 60. Instead I will read the temp and adjust the reading. Maybe my starting point is off because of that?

 

[1MadScientist]

Maybe Beersmith is throwing me off, but it seemed to work for me in the past. Entering this into BS it tells me to expect 1050 for the OG. The estimate for evaporation matches so I'm not sure where the difference is coming from.

Is there a "more" accurate way to measure gravity for pre-boil? I will cool my sample enough to not break my hydrometer, but not all the way to 60. Instead I will read the temp and adjust the reading. Maybe my starting point is off because of that?

Around + or - 5° of the calibrated temperature is recommended.