Author Topic: Help me tweak my BIAB equipment profile -- need more volume post-mash  (Read 2009 times)

Offline Horseflesh

  • BeerSmith Apprentice Brewer
  • **
  • Posts: 7
  • BeerSmith 2 Rocks!
I could use a hand tweaking my equipment profile.

I am using a single-vessel BIAB system, and the way I currently have it set up, after the mash I always need to add about 1/2 gallon of water to the kettle to hit the right pre-boil volume. I have been doing a quick and dirty cold water pour-over sparge to make up the missing volume.

This works OK, but I think I will get better results if my calculated water volume is a half gallon more than it is now. I would also like to skip the sparge step entirely.

I know I could just add a half gallon of water to my batches, but I would prefer that the Beersmith math is correct instead. What is the best way to accomplish this?

Here are some of my settings.

MASH TUN ADDITION is 4 gallons. This is equal to the approximate recoverable space under my mash screen.

LAUTER TUN LOSSES is set to 0 since I am doing BIAB, and the only water lost is whatever the grain absorbs. If I increase this number, so does Beersmith's total volume needed increase, but then my volume isn't tied as much to my grain amount.

LOSS TO TRUB AND CHILLER is set to 0.4 gal. This is about the amount of wort left in the kettle after pumping into the fermenter--the pump pickup is just above the bottom of the kettle.

BIAB GRAIN ABSORB is set to .496 fl oz/oz instead of the default .586. I did this long ago after I set up my current system, but maybe this needs to be tweaked. To get an extra 1/2 gal in the kettle I need to increase this value FAR above the default .586 though, so I don't think this is the way forward?

BOIL OFF is a very reliable 1.33 gal/hr.

Any ideas? Thanks for the help!

Offline Oginme

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 3104
  • Goats, guitars, and a home brew; Life is good!
    • Longvu LaManchas
Re: Help me tweak my BIAB equipment profile -- need more volume post-mash
« Reply #1 on: January 24, 2018, 05:55:56 AM »
OK,  Since you are doing full volume BIAB, set your mash tun addition to zero, as it does not really matter for your set up.  The purpose of it is to compensate for those people who do a traditional thick mash infusion and sparge steps to make sure they have enough water still with the grains to perform adequate conversion.  For those of us who do full volume BIAB, it really doesn't matter much since we a re doing a pretty think mash anyway.

You seem to have a good handle on your boil off rate, so you can leave that where it is.

The next step to tackle is your grain absorption.  If you measure your water going in and your pre-boil volume, then the difference is the amount of water which was removed with the grains.  Track this over a couple of brews and calculate the grain absorption rate by dividing this number by the weight of the grain for each of the brews you track.  You can update this number and it should bring you closer to balance for your water volumes. 

If you make this measurement a habit, it can help you in identifying and fixing any issues which may come up even before you finish a brew. 
Recycle your grains, feed them to a goat!

Offline Horseflesh

  • BeerSmith Apprentice Brewer
  • **
  • Posts: 7
  • BeerSmith 2 Rocks!
Re: Help me tweak my BIAB equipment profile -- need more volume post-mash
« Reply #2 on: January 24, 2018, 04:51:09 PM »
Thanks for the help. The grain absorption figure seemed like the key but the changes needed match what I am seeing were so far away from the default I got gunshy.