Porridge! (rolled oats)

[beanstalk]

Aye cool. Well I ended up at eleven litres cus I thought that's what batch size meant but maybe that means after bottling?

This is the one thing I need to get my head around big time. How to correct with gravity readings with temp adjustments by by diluting or boiling for longer etc in order to get consistent brews...any good sites or.books that go into this in greeat detail? Thanks for all your help folks, this site is a great resource!

[biertourist]

Cheers folks. I'm still getting used to beersmith, but it was saying no sparge just 18 litres mash water to end up with eleven after boil. I did fly sparge with one litre just to rinse the  bag and bring the pre-boil up to 16litres as it suggested in beersmith but I don't understand how I got such a high gravity. Maybe it was the oats or something. I used lidle jumbo oats, but I would have thought smaller oats would be more efficient?

No sparge should keep the efficiency quite low and using just whole uncrushed rolled oats should be less efficient, as you guessed.  65% efficiency actually sounds about right for no sparge brewing given the rest of your information so far, let me keep looking.

Adam

[biertourist]

Aye cool. Well I ended up at eleven litres cus I thought that's what batch size meant but maybe that means after bottling?

This is the one thing I need to get my head around big time. How to correct with gravity readings with temp adjustments by by diluting or boiling for longer etc in order to get consistent brews...any good sites or.books that go into this in greeat detail? Thanks for all your help folks, this site is a great resource!

You ended up with 11 liters when / where?  -Going into the fermenter or in your boil kettle after the boil?  Or coming out of your fermenter going into your bottling bucket?

-If you were supposed to end up with 13.47 liters post boil in the kettle and you ended up with 11 that would explain why your OG came in so high. (Either your boil off rate is way higher than you estimated or you didn't add as much water as you were supposed to.)


Adam

[biertourist]

You appear to have a BIAB system so getting accuracy and understanding your volumes is a bit trickier; I know how to do it for 3 vessel AG systems very easily; let me take a stab at it.

1. Calibrate your vessel volumes -if you have a site glass calibrate it by filling with 1 liter at time (or 2.5 liters -that will be faster) and making a mark / adding a vinyl sticker.  -If a site glass isn't in the cards, then just use a white plastic mash paddle and mark the liquid level as you fill the vessel with each 1 or 2.5 liters of water -use a knife to mark the liquid level and then write over it with a black permanent marker.  -Now you can accurately determine that you have the right amount of strike water.   You can also use this same mash paddle to tell your pre-boil and post boil volumes because you have a single vessel BIAB system -this part is way easier on BIAB.

2. Calculate the amount of water that will be absorbed by the grain ahead of time and account for this; in a typical mash tun the absorption rate is (sorry I don't have the metric absorption rate calculation but you can get there from here by converting): 0.125 gallons per lb of grist weight.  You'll probably end up with a tiny bit less absorption than this with BIAB because the grain is getting a bit compressed just by lifting the bag out of the vessel.

3. Actually measure your Pre-boil volume using your calibrated mash paddle from #1 above -make sure you're hitting this first, if you're not and you did accurately hit your HLT volume, then your absorption estimate is off and tweak it based upon what you actually saw and then this should be accurate for the next brew and you can move on to improving #4 below

4. Actually measure your Post-boil volume using your calibrated mash paddle from #2 above -now you know your boil off rate for a 60 minute boil-the diff between #3 and #4 -plug this into your brewing calculator and save it for the future, now you've turned one more variable in your system into a constant and your estimates will get better.

5. Measure how much liquid (if any) gets left behind in your kettle -if you're using a ball valve and a dip tube then there might be a small bit behind, if you just pour the bucket and filter the hops in a filter or something you might leave VERY little behind ---Note: This measurement will not effect your gravity; only the volume that you end up with in the fermenter.  It will impact your "brewhouse efficiency" # but not your mash efficiency #.

6. Assuming that you always make the same batch size, monitor your efficiency changes when you brew a normal strength beer vs. a strong beer vs. a low gravity beer; efficiency will normally start decreasing as you start filling up your mashtun fuller and brew higher gravity beers so you'll want a rough idea of what efficiency # to use when brewing a normal strength beer vs. a strong beer.

7. Don't forget to adjust your calculator for 90 minute boils --as long as you already know your boil off RATE the calculator should estimate this very well for you as long as you remember to tell it that you're going to do a 90 minute boil (for beers that use a large % of pilsner or lager malt)

8. Nothing will have a larger impact on your efficiency than your sparge techniques; if you start holding back some of the water for sparging and switch from no sparge to batch sparge or a small fly sparge/ rinsing your efficiency will change so also note that.

9. Minor: This is minor so I almost hesitate to put it in this same list as the major factors, but the mash efficiency is driven by the basemalt that you use; malts with higher %protein and higher diastatic power normally have lower extraction rates; Maris Otter has GREAT extraction rates.  If you switch from fat-looking European malts like Maris Otter to skinny-looking malts like US 2 row, you will see a drop in mash efficiency.  The MO grains just have more starch in them as a percentage cause they're physically fatter.

10. Minor-ish: Crush.  Especially since you're doing BIAB, feel free to tighten down the crush and get a few points more efficiency; it's not like you're going to get a stuck mash / sparge.  -Then just note your new efficiency levels in your brewing calculator and save them for later.


Locking in some aspects of efficiency seems harder for BIAB but many of them are actually easier.  Just focus on turning each variable into a constant -one brew at a time.  If you focus on the over-all problem of efficiency you'll never get there, you need to spend the time to make sure your volume is right, then figure out boil off rate, then figure out grain absorption, then figure out the change in efficiency as batch size and gravity changes.  -You can't figure all this out in one batch, but now you've got a roadmap to get you there.

An easy way to get there in a hurry is to find another experienced homebrewer who has a similar system to your who has already nailed down some of these aspects and plug their brewing calculator numbers into your system and THEN start tweaking to find your exact system numbers. -Start with another BIAB system with no sparge brewing and that should get you good brew house efficiency and mash efficiency #'s, but the boil off rate is determined by your electric element power and the height to width ratio of your boil kettle.



Adam

[beanstalk]

Holy crap my friend you've really gone out of your way there to help me get to the bottom of this, thank you so much! Can't reply properly cus on mobile but will dissect this properly when I get back tomorrow! Thanks again! 

[Sorcerers Apprentice]

Excellent advice Adam, shame to have it lost in a thread on porridge, could mods pull it out and perhaps make it a  sticky in Equipment on BIAB Calculations?