I'm doing a fairly large (1.080) Double IPA tonight/tomorrow and I'm wondering how to compensate for the lost efficiency with large grain bills. I'm planning on doing a longer boil (90 min - might do 120 min) to get more water in mash and sparge. If I hit my usual mash efficiency of 78%(ish), I should be in the neighborhood of 1.054 for Preboil OG. I'm planning on mashing at 152F with 1.33 qt/lb, and should be sparging right around that neighborhood too. Grain bill is thus (5 gal): 12 lb Optic 1 lb CaraRed 2.5 oz C60 1 lb table sugar My questions are: Based on the process outlined above, can I reasonably expect to hit my preboil numbers, or should I thin the mash, sparge or both and boil longer? Does anybody know what impact ambient temperature and humidity have on boil off rate? Usually, my boil off is a little shy of 1 gal/hr, especially over the summer. My intuition says I'll have a slightly higher rate now since the air is fairly dry, but I may be off. Thanks!
My efficiency is pretty stable at 78% for beers up to around 1.070 then it drops to 70% (sometimes a bit lower). I try to keep my mash in 1.25 to 1.33 qt/lb range as well depending on the limits of my mash tun (will also decrease batch size from 6 gallons to 5.25 if needed). For me the only way to compensate after mashing is to have some extra light dry extract on hand to boost gravity if needed. The extract shouldn't have too much effect on flavor in a beer like this. Just keep track of your preboil gravity and next time calculate that into your grain bill.
If you are a batch sparger and want a quantitative prediction of the expected change in your mash efficiency, BrewCipher has a calculator for that. I'd recommend other possibilities too, but I don't think I've seen that elsewhere.
Boil longer has no relation with efficiency(it just evaporate more water), to get a bit more eff. you could use 1.5 qt/lb mashing ratio .Mash a bit higher to compensate dextrines loss. I am not sure you will be able to have a 78%(ish) eff mashing for a 1080 OG, I think it is not very likely. Regarding your concern about the impact of ambient temp. and humidity on boil off rate I have absolutly no idea.
Thanks VikeMan, I'm using BrewCipher, just an outdated version apparently. So assuming 78% for 10lbs of grain (many of my batches are right around there), it looks like I should only take a hit of a couple points. Bully! @Tebuken the saving grace of this recipe is the pound of table sugar. That should get the OG up to 1.080. I've got a wee heavy lined up for when I've got more fermenters free. No sucrose in that one and a 16lb grain bill...I should probably just buy a few extra pounds of grain now.
There is something I don´t understand, according your given numbers you need 7 gals of 1054 OG wort as pre-boil volumen( boiling 120 min)?
That's exactly what it ended up being. And the boil time was somewhere in between at 105 minutes. OG is 1.081. I don't think I've ever been closer to projected numbers before.
