Left over at bottom of mash tun

A while back I posted a question regarding the pros and cons of 5 vs. 10 gallon Igloo beverage cooler mash tuns.Many thanks to those who took time to answer. I am getting ready to make the transition from extract/ steeping to partial mash. Before I purchased a cooler,I was given a brand new Igloo 28qt. rectangular cooler-without a drain. Adding one was not a problem.I located it as close to the bottom as possible allowing for room for sealing washer and gasket,which I kept to minimum size.Added a stainless braid as well documented in these forums.Voila.
My question regards the dead space in the cooler below the drain point, in my case bout 2.25 qts. during a water only test measurement. I realize in practice the vast majority of this space will be occupied by spent grain and stainless braid and not liquid. But it seems to me that this grain would be saturated.Realizing that others must have this same situation to some extent I was just wondering how they handled this undrainable wort? Thanks for your time.

After your first batch. note how far off your goal pre-boil volume you are. Then on your second batch compensate by adding more water to make up for that lost liquid.(or if you dont wanna risk a batch, add enough crushed grain to cover the bottom, pour in a gallon of water, lauter, and measure how much is left, then compensate)...Don't forget to calculate grain absorption as well(I think its .13gallons per pound of grain)

You factor it into your brewing software for how much water you need. You first add water to your cooler, perhaps 2 gallons and then drain it out your braid, then pour out the water in the deadspace and then measure that.

There's usually a spot (I know for sure in beersmith) that ask how much water in the deadspace.

The software will factor in grin absorption as well as the liquid in deadspace when it's telling you how much water needed for mash and sparge.

Tilt the cooler toward the outlet near the end of the sparge. The wort absorbed by the grain is typically about 0.20 gallons per pound and generally considered un-recoverable. You should be able to drain nearly everything if you tilt the tun at the end. The grain absorption volume is substantial, but very easy to compensate for.

Example:

10 lb grain bill
water/grain ratio = 1.5 qt/lb = 15 qts = 3.75 gallons of strike water
Grain Absorption = 0.20 gal/lb = 2 gallons
Net Volume= 3.75 - 2 = 1.75 gallons (initial run off volume)

Want 7 gallon pe-boil (one gallon lost to boil off and 1/2 gallon misc loss/racking etc)
Need: 5.25 gallons additional sparge water

I usually spit the 5.25 between the strike water and the sparge water, so i would probably go with 6.25 gallons of initial strike water followed by 2.75 gallons for the second run off.

+6.25 strike water
-2.00 gallons lost to grain absorption
+2.75 gallons sparge water
-1.00 gallons to boil off

Net Volume: 6 gallons post boil. Remember to up the volume even more if using a lot of hops and especially so for whole hops. Only estimated boil off and grain absorption have been considered above with an extra one gallon to account for miscellaneous losses, which might be the dead space of your tun, BK, Chiller, etc. Increase batch size as required to account for all losses on the way to the keg or bottle. It would probably be prudent to plug about 65% efficiency into your recipe for the first batch. Adjust accordingly for subsequent batches.

If you batch sparge, which would be best for a rectangular cooler, whatever is left after a no mash-out, double batch sparge will be such low gravity, it will almost be meaningless. rdwhahb!

Catt22 said:

Example:

10 lb grain bill
water/grain ratio = 1.5 qt/lb = 15 qts = 3.75 gallons of strike water
Grain Absorption = 0.20 gal/lb = 2 gallons
Net Volume= 3.75 - 2 = 1.75 gallons (initial run off volume)

Want 7 gallon pe-boil (one gallon lost to boil off and 1/2 gallon misc loss/racking etc)
Need: 5.25 gallons additional sparge water

I usually spit the 5.25 between the strike water and the sparge water, so i would probably go with 6.25 gallons of initial strike water followed by 2.75 gallons for the second run off.

+6.25 strike water
-2.00 gallons lost to grain absorption
+2.75 gallons sparge water
-1.00 gallons to boil off

Click to expand...

How do you get these numbers (6.25 and 2.75 gallons)?
Wouldnt 6.25 gal of strike water product very tin mash (2.3 qt/lb)?

I'm new to this but what's wrong with pouring it and straining the rest?

diS said:

How do you get these numbers (6.25 and 2.75 gallons)?
Wouldnt 6.25 gal of strike water product very tin mash (2.3 qt/lb)?

Click to expand...

Yes, it's a little on the thin side, but IME it won't make any difference at all.

The 6.25 is simply the strike water (based on 1.5 qt/lb) of 3.75 gallons, plus half of the required additional sparge water of 5.25 gallons and rounded down a bit from 6.38 gallons. This was just a general example of how to figure it. You could certainly reduce the water/grain ratio down to as little as 1 qt/lb if you wanted a thicker mash and make up the difference in the sparge.

Then it would be:
+ 2.5 gal initial strike water based on 1 qt/lb
+ 3.25 gal (half of additional sparge water)
Total water for first infusion = 5.75 gal
Initial Run Off = 3.75 gal

Second Infusion & Run Off = 3.25 gal (2nd half of additional sparge water)

Total Run off = 3.75 + 3.25 = 7.0 gal pre-boil

The aim is to make the run off volumes roughly equal, but this is only my personal preference. There are a number of other approaches that reportedly work just as well or better. Some dough in with the normal strike water ratio (1.0 to 2.0 qt/lb) and at the end of the conversion add all of the sparge water at once, then do a single run off. I don't have enough experience with batch sparging to suggest one method over another.

Thank you very much, I got it now.
Is there a difference in volume of sparge water between batch and fly sparging?

diS said:

Thank you very much, I got it now.
Is there a difference in volume of sparge water between batch and fly sparging?

Click to expand...

No, the sparge water volume will be the same for each. It's basically the total volume of water required less all of the losses you can account for such as grain absorption and what remains in the MT dead space, if any. It's easy and you can do the math with a pencil and paper and without a computer or special software. I use those too, so don't get me wrong, but not for such simple calculations as these.