First All Grain -- Mash/Sparge Calculations

I have most of the data I need to work backwards from target volume / OG to grain bill, etc. Bits and pieces indicate that equal volume runnings (1st/2nd) from batch sparging maximize efficiency. Given, that, I worked backwards to determine mash volume and sparge volume to get equal runnings. I know about various tools out there -- I just like to understand it first so it's not so magical.

The only thing that struck me as odd is the qt/lb mash ratio of 2.0. I can go all the way up to a 20lb grain will before it drops to 1.34 qt/lb. Given my systems constants, I'll have similar kettle volume depending on hops and boil time. Basically, I just have to adjust for grain absorption.

Is 2qt/lb an issue with anything during mashing?

Anyone have experimental data for hob absorption per oz?



The constants above (evap rate, deadspace) are based on my equipment.

Thanks,
-Josh

2.0 qts/l b isnt going to be a big deal... that is my normal mash thickness.

The amount of wort you lose to hops, will depend on leaf vs pellet as well.



Trying to make sense of the rest...

You want 5.5 to the fermentor, right?

5.5 to the fermentor
PLUS 1.36 BOIL OFF
PLUS .23 CONTRACTION
PLUS .06 BK LOSS

This means you need 7.15 gal to the kettle.

This means that if you mash in at 2.0 qt/lb:

STRIKE WATER is 5.5 gallons
LOSS TO ABSORPTION 1.43 gallons

SO you end up with 4.07 to the kettle BUT you subtract .5 gallons to MLT deadspace.

3.57 gallons to the kettle first runnings.

You still need 3.59 gallons to meet your BK target...

Meaning you need to add another 3.59 gallons of sparge water to the MLT and drain.

Looks good to me... just had to write it out!

While it's not a bad idea to have equal runnings, don't go crazy about it. If you o that, great. If you can't it won't make a huge difference. MY ROT is that if I can keep the runnings within a gal. or so, it's close enough.