Can anyone double check the water I need for my BIAB batch?

[Elysium]

I know this is something fairly newbie....but I dont seem to be able to find a definitive answer to my question: How much starting water do I need for my 4 gallon (final amount) batch with 9 lbs of MO (BIAB brewing)?

One site gave me 6.69 gallon and another one gave me 6.13 gallons of water.

I use a water bath to chill the wort...so equip loss wont happen there. My boil of rate is about 1.2 gallon/hour and I'll boil for 1 hour.

 

[mtnagel]

Just need to add up all the places where you lose water:

Grain Absorption: Figure 0.06-0.08 gallons absorbed per lb of grain depending on how you long you let it drain and how much you squeeze it.

So for your 9 lbs, that's 0.54 - 0.72 gal.

Boil Off: You said 1.2 gal/hr.

Cooling Shrinkage: Beer Smith says 4%.

On 4 gals, that is 0.16 gal.

Cooling loss: I know when I cool at home, I lose about 0.3 gal in the time it takes me to cool but that is for 5 gal.

You'd probably lose less with less volume, so maybe 0.25 gal.

So adding all those up, I get 2.33 gal lost (I assumed the 0.08 gal/lb grain absorption), so you'd start with 6.33 gal. Of course you can adjust my numbers up or down depending on what you know/assume.

 

[wilserbrewer]

Loss to trub and yeast cake might be 1/2 gallon as well. The numbers above seem low if you want a full 4 gallons of finished beer. Monitor volume as you go, if you are low after the mash you can pour a quart or two of water through the bag, if you are too high, you can extend the boil a bit...just keep late hop additions the same based on flame out. Work towards a finished volume as well as trying to predict it.

 

[1MadScientist]

Are you making a 1.066 beer?

Start with 5.25 gallons. That will get you at 4 gallons cooled, including the trub.

 

[mtnagel]

Are you saying that's the starting water before mashing?

If so, there is no way that's enough. He already said he's going to boil off 1.2 gal? What am I missing?

 

[1MadScientist]

Okay, I see that now.

Add another half gallon.

 

[mtnagel]

That still wouldn't be enough. See my math above.

 

[wilserbrewer]

That still wouldn't be enough. See my math above.

Which still seems light based on my WAG intuition, cheers!

 

[mtnagel]

Right. And as you said, if you add too much you can boil longer. If you add too little, you can "sparge" with some through the bag.

 

[Forrest-hunters]

https://www.homebrewtalk.com/f36/biab-strike-water-volume-temp-more-413374/

I just created the above link with an excel spreadsheet today and have updated it since I originally posted it. I have add ABV, ABW, calories and more too. I will post it tomorrow. Haven't tried it yet but it is based on numbers I used last summer when brewing. Let me know how it compares to you or if I need to add or delete anything.

 

[Elysium]

https://www.homebrewtalk.com/f36/biab-strike-water-volume-temp-more-413374/

I just created the above link with an excel spreadsheet today and have updated it since I originally posted it. I have add ABV, ABW, calories and more too. I will post it tomorrow. Haven't tried it yet but it is based on numbers I used last summer when brewing. Let me know how it compares to you or if I need to add or delete anything.

I must say I really like the spreadsheet. I am still playing with the numbers in it...but I ended up with 6.25 gallons of water for a 4-gallon batch. Thanks.

 

[el_caro]

My boil of rate is about 1.2 gallon/hour and I'll boil for 1 hour.

That figure seems a little excessive to requirements. Generally I try not to let boil-off exceed 15% tops per hour. Perhaps you could throttle back once you get a good hot break.
Any one else have thoughts on this?

 

[Elysium]

That figure seems a little excessive to requirements. Generally I try not to let boil-off exceed 15% tops per hour. Perhaps you could throttle back once you get a good hot break.
Any one else have thoughts on this?

My boil of rate was 26%. It's crazy, isnt it? I'll try to upload a video of the boiling wort. I think we used too much juice. The main problem is that people here seem to use gas-burners that create a nice rolling boil...because the fire comes from one, centered direction....while I was using 2 portable gas rings that have many small holes and war up the whole surface of the bottom of our pot. So...for my inexperienced eyes, it was difficult to tell when the hotbreak occured or if the boil was a nice, constant boil.