Brew 8+ gallons in a 9 gallons kettle? BIAB.

[Cynapse]

Hey all,

So I want to brew 8 or more gallons in my 9 gallon pot. I'm a BIABer. Is there a way I can just use the scaled amount of grain for an 8 gallon batch, soak the grains and after pulling the bag add in the remaining water before the boil?

This seems like it'd work, but someone check my math.

Thanks!

 

[DirtyOldDuck]

I don't do math, or BIAB for that matter, but I do know that water expands as you heat it. So, even if you could mash enough grain in that pot for a 10 gallon batch, that 8 gallons at room temperature is going to be 8 plus as you approach boiling, at which point the hot break will most likely take you over the top. What is your boil off rate? Mine is two gallons an hour, so if I wanted 8 gallons in the fermentor I would need a boil of 10 gallons (actually closer to 11 because I leave the trub in the BK). Personally, I would get a bigger brew pot before trying 10 gallon batches.

 

[daksin]

No, you're still going to have to boil at least 9 gallons (probably closer to 10) down to get 8 gallons of beer, which won't work. You need to have at least 25% of your preboil volume in headspace to avoid a nasty boilover.

 

[lebucheron]

I think he means he'd boil let's say 5 gal of water with the sugars from the grains that would be the equivalent of an 8gal batch, then after that's in his fermentor he'd top up with water to dilute it back to a 5% beer or so?
I made a DIPA 5gal batch in my 9gal pot and DAAaaMN, that thing was full even with a very very thick mash. The idea here would be instead of a 5gal 8% batch I could have taken the resulting wort and split it between 2 fermentors and topped up both to let's say around 4 gal each for a regular ol'IPA (depending how strong you want it).
I believe you lose hop power this way as that water you're topping up with hasn't been boiling with hops for an hour, so you'd need to play around with it. For myself, I'm just going to wait on anything over 6gal batches until I get a new pot.

 

[Cynapse]

Lebucheron is correct in what I'm trying to do. My boil off is really only about 0.5 gallons per batch or so right now btw.

I was thinking I could wait for the hot break to happen and boil a couple gallons of water in various other pots to add in after its over so all the water ending in fermenters is with the wort most of the boil. I'm hoping this keeps my bitterness and favors the same.

I basically just got set up for kegging and I have a 5 gallon and 3 gallon keg to fill and I don't want to brew twice to fill them both up. I'm just searching for the best way to fill both and am open to all ideas and suggestions.

 

[Epimetheus]

Others have reported maxing out various sized vessels and keeping a close watch for boil overs, so I think it is OK.

You could do it by a modified BIAB process - mash with however much water will fit, dunk sparge and return it all to the pot, boil what you have and add makeup water afterwards. That is what I do for 5.5 gallon batches in an 8 gallon pot. I have a little more leeway, but same idea. I still get boil overs on the hot break 'cuz I get bored and don't watch it closely.

It also depends how much grain you are using. A heavy beer with more than 12 pounds per 5 gallons would be difficult to scale to 8 gallons and fit all the mash in a 9 gallon pot.

Here is a mash calculator. Scroll down to see "Can I mash it?" Say 10 lbs per 5 gallon batch, so 16 lb for 8 gallons. Assume 1.5 quarts per lb of grain. The calculator says the total mash volume is 7.3 gallons. Assume water absorption is 1.3 gal/lb by this source . Your 16 lbs retains 2 gallons, so now you are down to 5. Dunk sparge with 3 gallons and back up to 8. Expansion at boiling is 4% so that is 8.3 gallons. Might keep a water spray bottle handy. Might try some Fermcap-S foam inhibitor. I would not add hops until after the hot break.

Boil it down to 7 gallons and after cooling to about 80F, add a gallon block of ice to bring it down to 65F.

The Magic 8 ball says "As I see it yes"