Biab Water

[drtomc]

Hi All,

Well, I think I'm all set for my first BIAB tonight (I figure mashing in the evening and leaving the NC cube out overnight is not quite NC, but rather not-very-much-chill ;-)), but I do have one question.

The information on how much water to use seems fuzzy.

I think PP has written 40L for a 23L batch. I presume that's allowing about 0.8-1.0L/Kg grain loss, but how much evaporation loss during the boil, and what kettle losses to you allow. I'm doing about 5Kg of grain, so that would be 35L to boil. Am I really going to shed 12L between evaporation and break gunge in a 90min boil?

T.

 

[Adamt]

Only one way to find out.... try it. Evaporation really does depend on your burner type, and pot geometry (and burner position).

That amount of evaporation is not unrealistic, though it is on the high side.

 

[reviled]

Hi All,

Well, I think I'm all set for my first BIAB tonight (I figure mashing in the evening and leaving the NC cube out overnight is not quite NC, but rather not-very-much-chill ;-)), but I do have one question.

The information on how much water to use seems fuzzy.

I think PP has written 40L for a 23L batch. I presume that's allowing about 0.8-1.0L/Kg grain loss, but how much evaporation loss during the boil, and what kettle losses to you allow. I'm doing about 5Kg of grain, so that would be 35L to boil. Am I really going to shed 12L between evaporation and break gunge in a 90min boil?

T.

Its definately possible mate, im not 100% sure on exact figures and neither will you be untill youve done your first batch, then youll have a better idea about evaporation rates... I still dont bother too much with all the maths, and just top the batch up in the fermenter to reach my desired OG

Edit : You also lose water due to grain absorbtion which is higher in BIAB than traditional

 

[drtomc]

Right. My burner isn't gutsy, and my pot is 50L. I guess I'm going to shed less rather than more water during the boil. Boiling longer to shed extra water doesn't sound thrilling, so perhaps I should start with a bit less water, say 35L.

T.

 

[reviled]

Right. My burner isn't gutsy, and my pot is 50L. I guess I'm going to shed less rather than more water during the boil. Boiling longer to shed extra water doesn't sound thrilling, so perhaps I should start with a bit less water, say 35L.

T.

Are you aiming for 23 litres?

 

[eric8]

I think you should prolly go with around 35l. My last brew I used about 6.5kgs of grain and ended up with around 24 litres of wort at the end of my boil. I used about 32-33 litres of water to start with.

Doesn't matter if you end up with less than 23 litres anyway, if it ends up being a higher SG just add some water, or just leave it and have a stronger beer.

Good luck with it and have fun!

 

[drtomc]

Yeah, I'm aiming for 23L. Possibly slightly under - I haven't measured my "cube" exactly, though it's supposedly 20L, which most people claim will usually fit 23L of wort for NC, but it's cylindrical rather than cubic, so it may not expand as much as the latter. 35L sounds good to me - it's easy to add water to the fermenter if necessary.

T.

 

[reviled]

Yeah, I'm aiming for 23L. Possibly slightly under - I haven't measured my "cube" exactly, though it's supposedly 20L, which most people claim will usually fit 23L of wort for NC, but it's cylindrical rather than cubic, so it may not expand as much as the latter. 35L sounds good to me - it's easy to add water to the fermenter if necessary.

T.

Im just thinking, 35 may even be too much depending...

I only have a 30 litre pot, the max I can fit is 4.2kg of Grain and 28 litres of water, and that gives me 20 litres post 60 min boil...

 

[Cocko]

drtomc,

I have been working with: loss of 500ml per Kg of Grain and 15% loss per 1hr of boil.... And don't forget about kettle loss....

So IMO: For 23L you would start with around 32L....

2 cents.

Cheers

 

[interestingmmm]

G day Drtomc.

I start with 37 Litres in a 50 litre pot.
Using 5Kg grain and keep monitoring my evaporation rate and time left, turning the rolling boil up or down slightly to achieve about 24 Litres everytime( in the fermenter), Chilled.
I have a Rambo 2 ring burner.

 

[Katherine]

drtomc

so we will see you name on the BIAB register tommorow...

Happy brewing, late one for you tonight then...?

 

[drtomc]

drtomc

so we will see you name on the BIAB register tommorow...

Happy brewing, late one for you tonight then...?

Thanks everyone for your good wishes! Yes, I expect to be on the register tomorrow.

Hopefully won't be too late, since I'm going to NC. The most likely cause of lateness will be the gutlessness of my gas ring. Indeed, following the method of heating with the grain in, I'll effectively get a step mash. ;-)

Since I work in computational molecular biology, I've been explaining to my colleagues I'm doing a molecular biology experiment. A protein structure guy explained some interesting details about enzyme activity and temperature, which I should write up some time for the non-and-very technical audience here.

T.

 

[drtomc]

I only have a 30 litre pot, the max I can fit is 4.2kg of Grain and 28 litres of water, and that gives me 20 litres post 60 min boil...

Hard to tell - Pistol Patch, in out-of-band communication, has pointed out that there is a wide range in evaporation loss depending on the geometry of the pot, the volume of liquid and the vigour of the boil, and that 35L is probably a good initial ballpark. We shall see.

T.

 

[seemax]

My experience suggests evaporation rate is linked to surface area and boiling rate. I have a 35cm diameter pot and with a gentle rolling boiling (burner off centre) I average about 2L loss per hour, but on occasion this can be as high as 3L.

I feel expressing evap loss rate as a percentage is incorrect. My loss rates are the same for a 12L and 30L boil.

For your first BIAB, don't worry too much, just go for it. If the beer is weak or strong, doesn't matter, it's all beer!!

worst case for me is 3L evap, 3L trub loss, approx 3L grain loss... so for a 23L batch i start with 32L.

If you achieve 75% efficiency (post-boil), and you want a SG 1.050 beer, you will need approx 6kg of grain.