Liam, Last night I emailed your post to Pat Hollingdale to see if he had suggestions for your reduced efficiency with BIAB and his response is below. He's just going into summer down under (Australia), as we are heading into winter, so takes the opportunity to rub it in, the bugger!CorneliusAlphonse wrote:Re: guingesrock- your statement regarding BIAB not being any less efficient - I use my bag as my grain filter both when I do biab and a more traditional cooler mash. I experience a definite efficiency drop doing biab compared to single batch sparge - drops from 75 down to ~67.
As mentioned he is one of the main BIAB pioneers, has an international BIAB site and is the author of BIABacus, so he should be the guy to know about this: http://beersmith.com/blog/2011/02/24/br ... odcast-10/" onclick="window.open(this.href);return false; (that interview with him also deals with efficiency)
Howdy Mark,
Hope all is well at your end........(personal stuff omitted)
As for a short answer on this, it’s very hard but I have done side by sides on batch and BIAB and achieved about 5% higher with BIAB. To do proper tests you have to do the same recipe side by side. The other thing you have to do is measure mash efficiency. Your friend has measured fermentor efficiency which just distorts things even more.
Anyway, I don’t encourage fine grinding at all, That is just as likely to cause problems – see: http://www.biabrewer.info/viewtopic.php?f=41&t=28" onclick="window.open(this.href);return false;. Heavy squeezing is not necessary unless your bag was far too fine. If it is good, a quick squeeze before pulling and another one just before the boil starts is all you need. A small false bottom shouldn’t cause any problems, not like a small bag can. As for the mash-out...
This is where we will begin to find an answer and that main answer we will find is time. You can’t do a 60 minute BIAB mash and expect the same efficiency as if you do a traditional mash followed by a good half hour or more of sparging. However if you pulled your BIAB bag at the same time as you were finishing your final traditional sparge, then you will find the BIAB will exceed the traditional brew.
So, time is the usual culprit. I have just added this as point number 10 of this post: http://www.biabrewer.info/viewtopic.php ... 9207#p9207" onclick="window.open(this.href);return false;. That post will find most inefficiency culprits. Many apply to all types of all-grain methods.
Hope this helps you Mark and keep warm!
Pat