First BIAB brew - calculating Boil Volume

[BrewJas]

Hi

I'm planning on doing my first BIAB brew this weekend and wanted to check how I work out the volume of water needed for the mash

I have a 19L pot and I am looking to adapt the following receipt posted by Clibit a while back

Batch Size (L): 10.0
Original Gravity (OG): 1.046
Final Gravity (FG): 1.012
Alcohol by Volume (ABV): 4.52 %
Colour (SRM): 3.4 (EBC): 6.7
Bitterness (IBU): 33.9 (Average)

2.000 kg Pale Malt (100%)

15.0 g Cascade Leaf (6% Alpha) @ 60 Minutes
10.0 g Amarillo Leaf (8% Alpha) @ 10 Minutes
10.0 g Cascade Leaf (6% Alpha) @ 10 Minutes
10.0 g Amarillo Leaf (8% Alpha) @ 0 Minutes
10.0 g Cascade Leaf (6% Alpha) @ 0 Minutes
Plus a dry hop of maybe 10-15g each for extra aroma

Mash at 66-67ðC for 60 Minutes.

I want to be able to bottle 10L, so I'm trying to reverse calc the water I need. So if I want to bottle 10L, I need (working back)

+1L loss in the fermentor for trub (my estimate)
+2L loss for boil evaporation (my estimate)
+1L loss for grain absorption (John Palmer suggests 0.5L / kg)
=14L mash

Does this seem right? If I mash 14L, do I need to increase the Malt by 40% (i.e. 2.4kg) in order to hit the same target gravity?

Any help appreciated!

Thanks
Jason

 

[Scrattajack]

I'm interested in answers to this too as working out water does my head in, to the point where I wing it. I'd suggest that grain would only go up by 20% though, based on your figures, as you'd lose no sugars etc from the boiling stage.

 

[cushyno]

Water loss from grain absorption suggested in BrewersFriend windows app is 0.9L/kg. This usually works out right for me. It depends how hard you squeeze the bag, and I squeeze pretty hard.

On a 23L batch my losses from boil are around 2.4L for a 60min boil (works out around 10%). Boil losses can depend on vigour of boil and cross sectional area of your kettle - you'll lose more from a short wide vessel than from a tall narrow one.

1L is a good estimate for trub loss.

Trying to solve this for you...
I've run this through the BrewersFriend app for you. I plugged in Safale US-05 as the yeast. Considering you've accounted for 1L of trub in the FV, I used a batch size of 11L. This also means upping your hops to get the same IBU

You'd have to hit 80% brewhouse efficiency to get that OG of 1.046 with 2kg of grain. Typically a good number to start at for your first BIAB is 65% efficiency, which would either:

1. Give you 1.037 OG and a possible 3.9% ABV
2. Or, require 2.400kg of pale malt to give you 1.045 OG and 4.8% ABV

This all gets a bit tricky to predict. The yeast you use and the success of your fermentation will influence your FG. US-05 is listed as 81% attenuation, so it may get you lower than your listed 1.012 FG. Other yeast will give you different mileage, S-04 may be closer to 1.012 but wouldn't suit the style (american hops) as well as US-05.

Here's what you get with US-05 and 2.4kg of pale malt:

Total water 14.89L for that weight of grain.

I hope that helps

 

[BrewJas]

Hi cushyno, thanks so much for taking the time to plug the numbers in, that’s really helped and gives me more confidence for my first brew! And as it happens I am using US-05!

I need to get the brewers friend app, looks invaluable and straight forward to use.

 

[MyQul]

The way to work out losses through boil off (well how I did it any way):

-Put 5L of water in your pot
-boil it for 30 mins
-measure how much is left
-minus this from 5L
-Double it gives you boil off for your 60 min boil