Sunday, June 28, 2020

BIAB - guesstimates

What's the OG?

Base malt |   OG    |   FG    | mash temps | ABV
     8            1.036    1.009     155 - 145      3.5%
     9.5         1.042    1.004     152 - 140      5.0%

I'm losing 8 - 10f over a 60 min. mash, that's not good.
this is during summer brewing. ( temps 75- 80 f. )
9lbs Rahr pale ale malt.
7 lbs Rahr Pale Ale, 1 lb brown malt
West Yorkshire Ale @ 78f ( a bit hot, 64/72 )

Heat loss to grain 

about 0.5 f / lb

(5 gal. batch size, full volume mash, 60 min biol)


Running the numbers in BIAB calculator, you start to get an idea of how grain affects the heat loss of the strike water. Assuming that your grain is room temp (70f) and you loose 0.3 gallons to the trube when transferring the wort to the fermenter.

Baseline wort:

5 gal. | 150 f mash | 60 min. boil

lbs. of grain | strike water volume | strike water temp

lbs. | SWV | SWT | loss
 7      6.8       154      4
 8      6.9       155      5
 9      7.0       155      5
10     7.0       156      6
11     7.1       156      6
12     7.1       157      7
13     7.2       157      7
14     7.2       158      8
15     7.2       158      8
16     7.3       159      9

And my measured results:

0.4f / lb of grain

Grain temp may have been 80f
Air temp was 75 - 80 f (summer, outside)
So, about a degree less than the above chart when brewing in the summer in a thick walled, 10 gal. Mega Pot.

lbs. | SWV | SWT | MT | loss
 8       7.0      158    155     3
9.5     7.0      156    152     4

Buy the ticket. Take the ride.


- BrewNorth

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