First 5G BIAB - EQ Profile/Mash Volume ?

[4JBrew]

So, I have a bayou classic 36qt (9G) SS kettle that I have been wanting to use for my BIAB sessions. I've done a few 2.5G batches in a similar vessel, but I'm ready to brew a rather simple Cream Ale BIAB style. I setup an EQ profile in Beer Smith, but I am confused about a few things. I'm thinking maybe I didn't set the profile up right, or I don't know how to calculate water volume. My entire grain bill is only 8 LBS. I plan on doing a 90 minute mash @150F. Beer Smith is calculating that I need to add 35qt (8.75G) of 154.4F Water. That leaves me with a wopping 1qt of volume to add my 8LBs of grain. Yeah, that's not going to happen. What I am doing wrong here? Has anyone created an equipment profile for this kettle? Additionally, how much water SHOULD I use to mash 8LBS of grain for this BIAB. So many calculators, so many different results. (part of my problem, I haven't calculated the true boil-off rate of this kettle/burner yet).

Thanks!

 

[LLBeanJ]

I have an 8 gal kettle and boiloff is 1.5g/hr. For an 8 lb grain bill and a 90 min boil, I'd be looking at 8.08 gal mash tun volume (obviously, I'd need to do a sparge, since my kettle is only 8 gal) and 7.45 gal water.

Aside from the boiloff rate given above, my mash tun dead space is zero (I dump it all in the fermenter), grain absorption is set to .3 fl oz/oz (I squeeze the bag to get as much liquid out of it as I can). This yields 5.0 gal total volume into the fermenter.

Edit: I corrected my boiloff setting. It is actually 1.5 gal/hr, not 1.3 as had stated initially.

 

[pricelessbrewing]

Wow. 3 fl oz / oz (.0375 gal/lb) of grain is a pretty tight squeeze. I squeeze pretty hard but have been modelling my calculations off of .08 gal/lb.

He said 90 minute mash not boil just fyi. I have a 30 qt pot, so I too have to sparge. My boil off is roughly 1.15 gallons. It's hard to get the same on my ols propane burner but I try to keep it consistant.

Shameless self promotion in water calculations, try my new one that I just posted. It's based in biabbrewing.coms calculator the one in an article recently. I wanted more details and sparging calculations so I added them myself.

Take a look, leave some feedback and any feature requests.
https://www.homebrewtalk.com/f244/b...r-modifications-now-includes-sparging-485015/

 

[4JBrew]

I have an 8 gal kettle and boiloff is 1.5g/hr. For an 8 lb grain bill and a 90 min boil, I'd be looking at 8.08 gal mash tun volume (obviously, I'd need to do a sparge, since my kettle is only 8 gal) and 7.45 gal water.

So, using the calculator priceless brewing quotes below, I'm about a gallon off of your calculations.
5gal Batch Size
8lb Grain Bill
1oz Hops
90 min boil (also doing a 90 min mash as stated above).....wait...I think I just figured it out (duh!). A 60 min boil = 8.66 gal mash tun volume (7.66 gal water). 90 min boil = 9.41 gal mash tun volume (8.41 gal water). This makes sense.. I'm still a little off from your values with a 60 minute boil, but I assume that's because of sparge (I'm not doing one). With that said, it looks like I can get away with close to 75 min boil if I have to max it out. What's confusing me even more though, is it's calculating the grain is only taking up 1 gal, yet the rackers (Can I mash it?) calculator says 8 lbs takes up over 3 gal of space.

 

[LLBeanJ]

A couple of things...

My numbers that I posted above are a little off. When I realized that the recipe I was using to provide you numbers had the boiloff rate a little off, I changed the boiloff rate but didn't update the total water volume and required mash tun volume, so both are little higher than I had stated.

Unless you have a lot of deadspace in your kettle that will result in a bunch of liquid not making it into the fermenter, you are going to considerably higher on your final volume into the fermenter.

Here is my volumes page from BeerSmith that reflects a recipe with an 8 lb grain bill and a 90 min boil. Boiloff has been corrected for 1.5 g/hr. Use these number for your recipe and you should be pretty close. After you've brewed once using these numbers, you can make any corrections you may need for the next brew. I would bet that these numbers will get you within ± a quart or so.

Edit/Update: I input my recipe/equipment variables into Priceless' spreadsheet and it came out fairly close to BS:
Total water = 7.55 vs 7.75 in BS
Mash volume = 8.55 vx 8.38 in BS

 

[pricelessbrewing]

It's because you have your trub loss set 0 in beersmith. My default value is .25 I think.

 

[LLBeanJ]

It's because you have your trub loss set 0 in beersmith. My default value is .25 I think.

I don't think that's it. I set the "Loss due to Trub" to zero in the spreadsheet to be same-same with BS. I also set Hops absorption to zero since BS doesn't utilize it. Here's a screenshot of the spreadsheet setup for the same recipe that the BS screenshot above is set for...
.
.

 

[pricelessbrewing]

I don't think that's it. I set the "Loss due to Trub" to zero in the spreadsheet to be same-same with BS. I also set Hops absorption to zero since BS doesn't utilize it. Here's a screenshot of the spreadsheet setup for the same recipe that the BS screenshot above is set for...
.
.

Gotcha, my only other guess would be how low your grain absorption value is. (.08-.037)x8=.34 gallons. I'll look into it more but I appreciate the feedback.

Nvm I see your setting for grain absorption in BS. I also noticed my grain volume estimation is a bit aggressive as well. (.0375-.03) x8= .06 gallons

Bs seems to distinguish between trub loss, and fermenter loss. I can only assume that's similar to mashtun dead space. Volume that can't be racked out. This is .5 gallons in your eq profile.

Those two would put you at 7.79 gallons.

 

[LLBeanJ]

Yeah, that's what I'm thinking. In BS, the default for grain volume is 0.652 l/kg, which I haven't changed. Not sure what your spreadsheet is using. That is likely where the discrepancy lies for required mash tun volume.

For the starting water volume, BS is adding in a 4% cooling loss factor. In my recipe, it is .21 gal. I'm assuming that this is to compensate for liquid expansion at mash/mashout temp since it would come into play at the post-mash/pre-boil stage. With a slight rounding error assumed (.01 gal), this would account for the .20 gal discrepancy between the BS and the spreadsheet.

 

[pricelessbrewing]

4% is the percent difference between the volumetric thermal expansion of water at boiling and at 68 degrees. Currently I only use 68 degrees, I'll be adding a temperature dependent volume size tomorrow most likely.

The differences seem to arise with the fermenter/bottling loss and the grain absorption.


It seems BS uses .07875 gal/lb actually. Which is close to my default value for grain absorption of .08 gal/lb with a hard squeeze. Non squeeze is often cited at .125gal/lb on here and other forums which is why I find it surprising bs assumes the volume of the grain is so small.

 

[LLBeanJ]

4% is the percent difference between the volumetric thermal expansion of water at boiling and at 68 degrees. Currently I only use 68 degrees, I'll be adding a temperature dependent volume size tomorrow most likely.

Makes sense.

It seems BS uses .07875 gal/lb actually. Which is close to my default value for grain absorption of .08 gal/lb with a hard squeeze. Non squeeze is often cited at .125gal/lb on here and other forums which is why I find it surprising bs assumes the volume of the grain is so small.

Yep. When I first started brewing I used BeerSmith's default BIAB absorption rate but found that my preboil volumes were a little high. I then essentially cut the absorption rate in half and took care of it.

 

[SlickTX]

Your initial numbers from BS look pretty close.

I did a BIAB of a light-ish ale a few weeks ago in the same kettle you have. BS said I needed 8.2 gal of water to start. Not gonna happen in a 9 gal kettle. I put in 6 gallons and a roughly 10.5 lb grain bill. After a decent squeeze and a 60 min boil I got 4 gal into the fermenter. I topped of with 1.25 gal of water. I bottled exactly 48 bottles and had maybe a 1/2 bottle left in the bottling bucket so my guess of 5.25 gal in the fermenter was right on.

I'm thinking I need ~ 7.25 gal of water to start and I've upped my game to an 11 gal Bayou Classic pot to handle that. It will take some time to dial things in and I'm looking forward to it.