BIAB dunk sparge efficiency benefits?

[Markbeer]

I first starded sparging with biab when I did my first high gravity brew. I now do it all the time.

I believe alot of it has to do with the concentration of sugar vs water. ie add boiling water and it leaches out the sugar as they go from high concentration to low.

I will do 2 dunk sparges each for 10 minutes. I find it almost essential to do to be able to het decent efficuebcy in a 1075 plus brew.

for something like a mild I wouldn't bother.

this has stopped me from going to a 3v. I struggled to get decent efficuency for anything over 1055 until i started sparging.

Mark

 

[brewbienewbie]

Ok so yesterday I did a repeat of last week's brew, but added a sparge step and my efficiency is back to normal. Gravity's seven points higher this time, I'm a happy man. I think I maybe could've got the same result if I mashed out properly, but for my system sparging with 6L or so of boiling water is much less effort.

 

[Bribie G]

I'm doing an English 7% IPA for this years' comps. I'll do a single infusion mash plus mashout, then a dunky today and see how it goes. I've set my efficiency in Brewmate to 75% that's normally spot on for my regular 5% brews, lets see how it goes for a stronger brew. I'll reserve 10L of my original strike liquor for the purpose and use my immersion heater to take it to 78 degrees for the sparge.

Bribie puts chalk marks on neighbours' garage door to measure pissing height B)

 

[Bribie G]

Great moments of BIAB.
Warning: do not attempt this with a Braumeister.





door go up, bag go up, door go down, bag go down. :lol: :lol: :lol: :lol:

edit: the gravity of those second runnings is 1.030 as opposed to about 1.060 (approx) for a similar 1.070 IPA done on "pure" BIAB so there's obviously less wasted sugaz now trapped in the grain ball. Not a heck of a lot I'd guess, but interested to see the final efficiency.

 

[stux]

Dunk sparge can be almost perfectly modelled as a dilution.

So, the trapped sugars in the grain is just about equal to the real absorption of the grain at the mash gravity (the runnings)

Say there's 10L of absorption (real absorption, not apparent) at 1.060, then when you add another 10L of dunk sparge liquor you dilute, that to 1.030.

You then run off almost exactly the sparge liquor you added, ie 10L at 1.030...

And you're now left with 10L of 1.030 in your grain...

Another 10L sparge would get you another 10L of 1.015.

Calculating the real absorption is the trick, as it includes the volume of the extract.

With my triple batches it works out best if I can have 20L of sparge in a 50L pot. The limiting factor is the size of the pot as it must'nt overflow when you add the sodden grain!

PS: I find it best to dunk the bag, then open it and agitate with your masher (potato), to rewet all the grains. You're basically doing another mini biab. I let it soak while occasionally mashing again for 10 minutes... then hoist and drain off my second sky hook!


Attached pictures, first one is raising the bag and draining it, while bringing the wort up to boil temp.

Second is draining the dunk sparge.

I have a 2ring burner under the dunk sparge pot, and will bring that to the boil too, then pour it back into the main boil as I can as far as I can, volume allowing. I have an 11.5L/hr boil-off, so will get most of it in within 30-40 minutes I guess.

More Info on my 98/50L Maxi-BIAB setup
Triple Batch Maxi-BIAB in 98L Kettle with 50L dunk sparge pot

 

[Bribie G]

In my old place the urn(s) used to sit on a tool trolley and I would use one skyhook but move the trolley to position urn 1, urn 2 or the sparge bucket under the skyhook. Very impressive about bringing the dunk sparge pot up to the boil as well. I never thought about that but I have a perfectly good Kambrook single ring 2kw heater not earning its keep ... will try that next time I do a higher grav beer.

 

[Bribie G]

I finally pitched the UK IPA just now and took a refrac reading of the wort as it went into the FV.. 73% efficiency according to BrewMate.

I'm pleased about that as it's a 6.2% ABV jobbie and I normally hit around 74% on my 5% brews.

edit IPA not APA