How to follow a recipe for BIAB ?

[bluphil52]

Hi I'm new to this,don't want to sound like a dummy
I'm getting confused on how to follow recipes?!?
Example:-

Make- 23 litres.

For the mash -15 litres
For the boil- 27 litres
Total liquor 34 litres

I presumed you start with the 15 litres water and add grains to do mash?!?

Can someone please tell me step by step what I need to do?!?

On another I did my recipe was 10.7 litres mash, but my grain didn't reach the water in boiler kettle?!? As it was so shallow. ?

 

[LLBeanJ]

The standard method for BIAB is to mash with ALL of your water, so that when you remove the grains you'll be left with your pre-boil volume without having to add any more water. Of course, this assumes that your boil kettle is large enough to accommodate the all the water and the grain. If it will not, then you'll need to do some sort of sparge.

You will need to calculate your total water volume...

Total water volume = Batch size into fermenter + expected boiloff (usually 1.0 to 1.5 gal/hour) + grain absorption (for BIAB assume .05gal/lb if you squeeze the bag, .1gal/lb if you don't) + expected kettle loss to trub (this would be zero if, like I do, you just dump the contents of your kettle into the fermenter and leave nothing behind, except maybe straining out the hops). Obviously, you'll need to convert to metric.

If your kettle cannot accommodate it all, then the formula is the same, but you just hold back a portion of the water (say, 1-2 gals) from the mash and then use the leftover water to sparge once you pull your grains. Common BIAB sparge methods are 1) dunk sparge or 2) pour over grains sparge.

 

[boydster]

Like LLBeanJ mentioned, it's very common to do a full-volume mash with BIAB and that means you don't use extra water after mashing. When I first started BIAB (and still sometimes if I'm using more or less grain than usual or doing a different sized batch) I used www.simplebiabcalculator.com to help get my volume and strike temp right. For a full volume mash, just enter in the appropriate values for each of the fields (if you don't know your boiloff rate, enter in 1.5gallons/hour to start and adjust as you get used to your system) and leave the "mashout" box unchecked. It will tell you how much water to use and what temp to heat your strike water to before adding the grains.