Step Mash Calculation

Question

I just brewed my hefeweizen for the 3rd time. At the time of the first batch I'd read an article that suggested a ferulic acid rest at 110°F to accentuate the banana notes in the aroma.
I mash in a picnic cooler a la @DennyConn and am having issues with the raising the mash temp to the 150s.

Initial mash is 11.75 lbs of grain and 2.9 Gal. of water @116°F. I hit the temp fine and let it rest 20 mins. At 20 mins, I added 3.8 Gal. of water at 170°F and only hit 140°F.

I used the strike temp calculator at Homebrewing.com with the following data:

• Grain Mass - 34 lbs (2.9 Gal. water (@8.5lb/Gal) + 11.75 lbs)
• Grain temp - 110°F
• Water amount 3.8 Gal.
• Target Mash 152°F

I verified using a different calculator and got similar results. What am I missing?

Also, BeerSmith showed that I needed to use 189°F water for the sac rest and I ignored it in lieu of my regular calculator.

(BTW, I added another 1.5 Gal. at near boiling to her the mash to 150°F to salvage the mash)

Answer 1

Based on what you provided.

11.76 lb grain

2.9 gal water

110f current temp.

You would need to add. 3.8gal of 190°F water to reach 152°F in the mash.

You need to use a mash Infusion calculator, not a strike water calculator.

You added water weight to grain weight and used a strike water calculator. Which would instruct to add 3.8gal at 170f. Unfortunately heat transfer math for liquid is different than dry grain.

Fyi: Because the infusion is above 170° the infusion water would need treated to a pH of 6.0 or below, to avoid tannins.