Brew In a Bag - What Efficiency Can I Expect?

I really don't have much experience with BIAB, but I would say figure about .7 or .8 Gal/hr boil off. Also your water measurements seem off (unless I'm missing something). I would mash with about 3.2 gal and sparge with about 4.4gal.
I'm not sure what your pre-boil og should be, but you can just take a hydrometer reading after mashing, before boiling (remember to adjust for temp). You could try plugging the pre-boil water volume into you calculator as the final volume (or batch size), then see what it says the FG should be. That should be pretty close to the pre-boil gravity. The only variable there would be the mash efficiency. I would use about 70% efficiency to figure your recipe the first time.
As for higher or lower, I think it would vary for everyone. But if you have a big enough bag, and the mash and sparge water can flow through the grains easily I don't see why there would be a difference. IOW, done properly, it should be pretty damn close. It's my understanding that the bag only replaces the screen or the false bottom of the mash tun.

 

I think 70% is a good starting point. I did one BIAB batch and got 69% (and squeezed the bag like it owed me money.)

 

I have gotten as high as 85%, but average around 70/75%. I am not a fan of bag squeezing, if gravity can pull it out while it rests it goes into the kettle, otherwise it goes to compost.

 

I get about 65. I'm not very good about insulating though

 

10/15 minutes while the kettle comes to boil.

 

The OP stated that they intend to brew via the Brew in a Bag (BIAB) method. My understanding of the BIAB method is that you mash the grains (in the bag) and then simply remove the bag.

The OP then stated: “Modified 'sparge' with 3 gallons (depending on future, better boil-off prediction)”. So, a sparge is intended? If that is the case then based upon my understanding of the BIAB method (as detailed above) the OP will not be mashing as per the BIAB method.

I am uncertain what the terminology of “Modified ‘sparge’” means. Is the intention to conduct a fly sparge? Is the intention to conduct a batch sparge?

Cheers!

 

I think in BIAB a dunk sparge would be the batch sparge equivalent and Fly sparge would be exactly the same but rinsing the grains through the bag.

 

I have done a modified brew in the bag (essentially) with batch sparging. Mind you, this is not my normal mode of brewing. I ended up using a biab to lauter a couple sparges that stuck because of adjunct grains. I scooped out the mash tun and strained the contents through the bag, directing the liquid to the boil kettle. I then put the biab with semi-spent grain in the mash tun and added my sparge water. I swriled the bag in the water to simulate stirring the batchsparge, but was careful to keep the grain in the bag so I didn't have to scoop stuff up again. These were not the most elegant brew days!

 

In the OP: “And what seems to be the most common outcome for BIAB - slightly higher or slightly lower efficiency?”

Since sjverla appears to be doing something different than BIAB (since: modified sparge) it seems that the proper question should be what kind of efficiency can he expect from his BIAB plus modified sparge method?

I personally do not know the answer to the above question but maybe somebody else can opine on this topic.

Cheers!

 

Some people swear by it, so it can't hurt to try. Be very careful or you'll end up with grains in your wort like I've done before and you'll have to filter all over again.

 

“I don't know if this has any real benefit, but it might, at least in my head.” Rinsing your grains will most definitely have a benefit. You are essentially conducting a fly sparge. The ‘challenge’ is quantifying your overall method with an accurate estimate of efficiency.

Brewers who conduct a ‘conscientious’ fly sparge are capable of obtaining very high efficiencies. A ‘conscientious’ fly sparge means that you maintain a small amount of hot water on top of the grain bed and maintain this small amount of hot water via slowly adding small amounts of sparge water to maintain this low amount. A ‘conscientious’ fly sparge could take something like 45 minutes. If you rinse your grains over a shorter time period (let’s say 10-15 minutes for discussion purposes) you will obtain a lower efficiency then a conscientious fly sparge brewer would.

Cheers!

 

I've been doing BIAB when brewing on a tight schedule (e.g. trying to get 4 batches in during a brewing session instead of 2) and have had great luck with it.

My efficiency is consistently around 82% (n=4, SD ~1%), however I've only brewed beers in the O.G. range of 1.048-1.065, so nothing big (1.075+), which I think is where BIAB efficiency may really drop off (Completely speculation).

Regarding process, my efficiency may be high due to extensive recirculation of the BIAB mash (when mashing in, while maintaining mash temp and heating up to mash out). I haven't "sparged" my BIAB mashes, although I do take the mash bag and place it on a large metal double colander on top of a Homer's bucket to drain (no squeezing, just gravity), and then add the drainage back to the kettle.

If just doing a 2-row and Simcoe SMaSH, just keep it simple and stick with your schedule, even if efficiency goes up or down. You'll already be doing something new, so why add another variable or more hassle to the brew day. If its not as hoppy as you want, you can always up the dry hop amount.

Your boil off amount will be the same as your normal boil off amount (e.g. x gallons per 1 hour). I've had a little bit of an issue calculating the mash water volumes due to the amount of water absorption by the grains, but just keep good notes and adjust future batches.

 

I was getting ~65% when I did BIAB. I dont have a mill so i didnt have control of my crush, so I think a finer grind is best for the BIAB method if you have an adjustable mill.

 

Ball valve of kettle open, out to march pump, back up into kettle recirculation fitting. I noticed above you have no kettle valve, so that obviously won't work for you. Best thing I can say to do would be to stir very well and add a little bit of grain at a time when adding grain to the mash water. The first time started recirculating after mashing in, my efficiency went up about 10%.

To each his own. I've started backing off the hops a bit on my hoppy beers as I felt I've been going overboard on the late hops and dry hops and as a result my beers were suffering (Coming off a little muddled). My previous comment was more about not switching it up on brew day, as its just another variable to deal with, but if you're comfortable, go for it.