another water calculation question

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Dec 1, 2008
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10.25lbs of grain hoping for 5.5 gallons of wort in fermenter

deadspace is big 7 liters
boil off 1 gallon
leave behind .5 in the kettle with the drek

so i was thinking a thin mash at 1.7 qts per pound is 17.4 qts. about 4.5 gallons.

can i just sparge (about 2.5 gal) til i get to 7 gallons then boil off 1 and leave .5 behind to end up with 5.5 in fermenter.

where does the dead space fit in here . do i have to add that to the 4.5 i always have issues with water calculations.

its a aio with recirc pump. does that mean theres no real dead space cause the water in dead space gets pumped back up over the grain. and i dont have to add it anywhere.

It depends on what software you're using. Some differentiate between recoverable and non-recoverable dead space. That is, the recoverable deadspace is area that the grain will never touch (like under the basket or false bottom) and non-recoverable dead space is the volume of liquid that gets stuck in the vessel after full draining. That is only relevant on a dedicated mash tun in a multi-vessel brewing system.
There is software that differentiates between recoverable and non-recoverable dead space??

As far as I'm concerned, any water in a dead space will eventually affect the chemistry of the overall wort by the way of diffusion. That is without regard to whether the wort is recirculated or not. However, I am a fan of recirculating wort during a mash since that is the BEST way to achieve good mixing during a mash.

My recommendation is to include all of the water volume in your tun when figuring concentrations or pH results.
deadspace is big 7 liters
Is that the volume underneath the basket, while mashing (with recirculation)?
If so, that's not deadspace. That whole volume of wort will be part of your boil volume after the mash is done, and the basket allowed to drain out fully.

Now any wort (sugars) still trapped in the drained grain in the basket would be lost. Unless, after you've fully drained it, you then sparge (with water) to recover as much of the trapped sugars as possible. The volume of recovered wort/sugars from sparging will need to be included in your water calculations, of course.
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