I'm embarking on my first batch with a mash tun cooler this weekend. I've got 15.1 lbs grain going in. I have 1 gallon of deadspace on the bottom and I'll be batch sparging. For 5 gallons to go into the fermentor I have to start with 6.5 gallons of wort for a 90 minute boil. My calculations so far are: Mash with 1.5 qt/pound= 5.66 gal mash -2.26 gal to absorption (splitting the difference discussed here) -1.00 gal to deadspace =2.4 gallons 1st runnings My question is: Do I need to account for another -2.66 gallons in the sparge too? Or since the grain is already saturated can I just go ahead and sparge with 4.1 gallons to get to my requisite 6.5? Thanks!
I've read over and over that it's about a cup of water per pound that you'll lose to absorption. This is overkill. If you plan for this, and your deadspace, you'll be fine. Edt: On a side note, I'd rather have to add MORE water because I came up shy than try to boil 10 gal of wort down for a 5 gal batch.
I probably am overshooting a bit. This is only my 2nd AG batch and my first was a BIAB. For that I tried to mash thin (>2 qts/lb) but the bag held things together tighter than expected so there was a lot of fluid around the sides. But for 10lbs of grain I lost 1 gallon of water. So really, I guess that's a better starting point to go with 0.1 than .15 because I have at least one result that indicates .1 gallons lost per pound. But as AlCaponeJr loves to point out and I heartily agree, when n=1 significance=0...I'm using more Algebra in brewing than I ever have in anything else. Eh, at least I can someday tell my hypothetical kids that it may actually matter...
FWIW: I consistently lose 0.13 gallons per pound of grain to grain absorption on my first runnings. And that's with my 0.19 gallons of dead space factored into the run.
A gallon's kind of a lot to lose to dead space. But I'll assume you measured that? Anyway, no, you don't need to subtract grain absorption or dead space twice. Just subtract the volume of your first runnings from your intended batch size, and that's your sparge volume.
Yeah, kind of bummed about it. I went with a cheap cooler from Target that I bought online and never saw in-store. Turns out the spigot is ~1" above the bottom for some reason and there's no channel or anything leading to it. So after measuring, it turns out to be pretty close to a gallon.
My absorption loss was always around 0.15 gal/lb and deadspace on an igloo cooler mashtun was 0.5 gal. Looks about right to me, don't forget to factor in water loss to hops and steam during the boil too. Using pellets, I always add another 0.10 gal for every ounce of hops in the boil and it seems to keep me about on target volume.
If I were in your shoes I'd spring for the right cooler and make a new one now. Losing 1 gallon of wort each brew day will easily cost you more in the long run than replacing the cooler.
It's a whole different animal with grain in the tun. I mashed with 5.5 gallons (fell a little short on temp...oh well), mashed out with 1 gallon and got 4.5 for the first runnings. If we assume .1 gallons absorbed/pound, that's nearly 1.5 lost to absorption and only a half gallon to dead space. I'm sure it's not ideal, but it's better than I expected. Also got 74.6% efficiency, so that was better than I allotted for as well. All in all, I think it'll be a workable system.
