I'm gonna try my first decoction mash (and second step mash) for tomorrow's Hefeweizen. Can y'all double check my process (and my math
)? I'm intentionally pulling slightly larger decoction volumes than it says it needs to compensate for any temperature loss in the mash. I normally just do a straight single infusion somewhere between 147-160 (depending on the beer), and skip mash out. The one step mash I did was infusions from protein rest to conversion rest, still with no mash out. So I'm unsure on some of this stuff.
Using this formula from How to Brew: Vd=[(T2-T1)(0.4*G+2*W)]/[(Td-T1)(0.4Gd+Wd)]
I mash in for my protein rest, 122F, with 11.25 quarts at 132F. I hold this for 20 minutes. (numbers thanks to the Brewers Friend mash infusion calculator).
I want a next step of 150, so Vd=[(150-122)(0.4(9)+2(11.25)]/[(212-122)(0.4(1/(0.6+0.32))+2(1/(0.6+0.32))(.6))]=4.669. In other words, I pull off 5 quarts of thick mash, heat it to 150, hold it for 20 minutes, then boil for 20 minutes. Add slowly back to mash checking temperature the whole way. Will have both boiling and cold water on hand to adjust if necessary.
That’ll get me to conversion temp of 150. Hold for 45 minutes.
Next step is 168, so Vd=[(168-150)(0.4(9)+2(11.25)]/[(212-150)(0.4(1/(0.9+0.32))+2(1/(0.9+0.32))(0.9))]=4.2. So I pull 4.5 quarts of thin mash, heat to 160 for 20 minutes, then boil for 20, add back, again adjusting if necessary with boiling or cold water.
That’ll get me at 168 mash out. Hold for 10 minutes or so, then sparge and proceed as usual.
Am I missing anything?