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-   -   mash temp confusion (http://www.homebrewtalk.com/f36/mash-temp-confusion-399421/)

tomas77 03-21-2013 02:28 PM

mash temp confusion
 
I mashed in at 164degrees waited till it hit 152degrees then shut lid and waited an hour. Opened lid temp was at 160degrees but went down to 152 right away. Was I mashing at 160 or 152? At the start I did have to stir a bit to bring temp down. This ever happen to anyone?

duboman 03-21-2013 02:47 PM

Sounds like your thermometer either needs to be calibrated or it is not reading the temperature instantly. If your strike water was in fact 164 and you stirred well it should have settled at 152 or so once the grain was stirred in and settled, i'd RDWHAHB but be sure to calibrate your thermometer:)

mo_feezy 03-21-2013 02:51 PM

you'll usually need to check the temp in a few spots in the mashtun. Yesterday I was shooting for 150, and had some areas in the mlt that were 154 and some that were 148. There were more that were 148 than 154, but even with stirring ever 10-15 minutes the temp varied throughout the tun.

billl 03-21-2013 03:04 PM

"Was I mashing at 160 or 152?"

Both - and more temps too. Heat rises, so if you let it sit there a while, the top is hotter than the bottom. That is one of the many advantages to stirring, stirring, and stirring some more - keeping a uniform temp.

tomas77 03-21-2013 03:49 PM

adding dme
 
Hi me again, After mashing took a reading and had a 1.069 instead of the 1.083 I was supposed to have. How much dme would I have to add to achieve this gravity. I really don't want to boil down to it either. Thanks.

rklinck 03-21-2013 04:02 PM

DME will add 40 total points of gravity per pound to your brew. So if you are doing a 5 gallon batch, each pound of DME will at 8 points to your OG. So about 2 pounds.

EDIT: Agree with abrix below. My response was based upon a final adjustment. If 1.083 is supposed to be your OG and 1.069 is your preboil, it is a different question. I have a higher boil off rate than abrix. A preboil gravity of 1.069 would get me above the 1.083 OG. If I was you, I would not mess with it. If your OG ends up off a bit, it is not a big deal.

abrix 03-21-2013 04:09 PM

1.069 is your pre-boil gravity, correct?

Then the answer depends on how long your boil is and what your evaporation rate is. For me, with my usual 90 minute boil, if my target original gravity is 1.083, I need to be at 1.071 at the start of the boil. For a 60 minute boil, I'd need to be at 1.074.

Which would mean you're looking at 0.25 - 0.63 lbs of DME at 40 points per pound per gallon. (40 ppg is at the low end for DMEs, so it makes for a safe estimate.)

RmikeVT 03-21-2013 04:13 PM

^^ If thats your Pre-Boil don't add any DME.

billl 03-21-2013 05:23 PM

Just for reference, you can estimate your OG based on the pre-boil gravity by multiplying by the ratio of the volumes. eg if you have 7 gallons and plan to boil down to 5.5, then you would do 69 x 7/5.5 = 87 or 1.087. You'll lose a little wort to hop absorption etc, but that is the ballpark.

Mithranbeer 03-21-2013 05:55 PM

Quote:

Originally Posted by billl
Heat rises, so if you let it sit there a while, the top is hotter than the bottom

Just being a pedant, but no. Heat radiates and or conducts - "moves" from hotter things to colder things to reach equilibrium. Hot air or fluid appears to rise due to cold air being denser and sinking. I doubt there's convection happening in your mash tun unless it's very very wet and you're heating the bottom.


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