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Pilotpip · 08-23-2012, 04:20 AM

Just switched to BIAB and on the last two brews I've managed to get only 4.5 gallons into the fermenter. I've been pretty close on my numbers and had good efficiency so I have good beer, just not as much.

When extract brewing I started with 6.5 gallons of water and had just over 5 after an hour boil. I figured the boil rate would be the same but apparently it is not. Any ideas? Should I simply adjust to have more wort at the start of the boil?

**fifelee** · 08-23-2012, 04:26 AM

The boil off rate won't be any different as long as you are using the same pot. If you are hitting your numbers and getting the efficiency you want then you need more grain.

**RM-MN** · 08-23-2012, 11:30 AM

Did you squeeze all the wort you could out of the bag? You could be losing 1/2 gallon right there. If that isn't the case, try doing a dunk sparge with your bag of grain to get more sugars and liquid into your boil kettle.

**chally** · 08-23-2012, 11:38 AM

Are you accounting for increased grain absorption? If you are putting 10+ pounds of grain into 6.5 gallons of water, the spent grain takes a lot with it when you pull it. Or did you mean you are starting with 6.5 gallons post-mash? I agree with the above poster that your boil off rate should be the same as before.

Either way, the solution is to add more water at the front end and add more grain if you need it to hit your numbers in the larger volume.

**T-Dan** · 08-23-2012, 11:38 AM

What I have noticed from doing partial mashes is that the LME and Dme take up some space in the kettle during the boil. So if you use more grain, and less extract, you will seem to have more boil off.

In other words, based on the marks i have on my stir paddle, my boil volume will go up as i add extract, as much as half a gallon if adding LME and DME.

**wilserbrewer** · 08-23-2012, 12:20 PM

Yes! start w/ more water, and measure your pre boil volume....if low, you can trickle some sparge water through the grainbag to reach req'd volume.

Pilotpip · 08-23-2012, 03:01 PM

That's where I'm confused. I am measuring my volume and starting with the exact same pre-boil volume as I was when doing extract. I guess I'll up my strike water to compensate. So far I'm getting good (70-75%) efficiency out of no sparge so I'll hold off on that and maybe add a bit more to the strike water.

Thanks

**chally** · 08-23-2012, 03:27 PM

Quote:

Originally Posted by Pilotpip

That's where I'm confused. I am measuring my volume and starting with the exact same pre-boil volume as I was when doing extract. I guess I'll up my strike water to compensate. So far I'm getting good (70-75%) efficiency out of no sparge so I'll hold off on that and maybe add a bit more to the strike water.

Thanks

Interesting. If your pre-boil volume is the same, there are only a few places where the loss could be occuring.

1. Pre-boil measurement. If you measured your extract water at 6.5 gallons cold and your all-grain water at 6.5 gallons hot, then you would actually have more extract water (hot water expands).

2. Boil length and intensity. Assuming you are boiling for the same amount of time in the same pot, you might be getting more boil off with all grain because you are not taking the pot off the boil to add the extract (which also cools down the wort).

3. Trub. If you are using Irish Moss or Whirlfloc in the boil, you might be leaving more protein and hops trub in your boil kettle with your all grain brews than you were with extract.

Assuming all of your equipment and techniques are otherwise the same, those are about the only things I can think of to account for the loss.

Pilotpip · 08-27-2012, 02:29 PM

I'm thinking 2 is the culprit. Most extract kits that I did had 1/2 gallon lme in them.

Oh well, the next couple batches will only have about 40 bottles of good beer instead of 50

ReverseApacheMaster · 08-27-2012, 02:43 PM

Sounds like you are not accounting for grain absorption.