(DONE) Mash Calculator Issues

[Nosybear]

I used the Mash Calculator today to run a Hochkurz mash and ran into an issue I want to report. The masses and volumes will seem small - my current process is a very big partial mash, a bit of extract and a partial boil. Here was my planned mash schedule for 7.75# grain at 30°F (I had the grains in the freezer to keep them from staling - had to stall my brew day a couple of days):

Rest 1: 145°, 30 mins. Strike temp 162°. Actual resulting temp 145°
Rest 2: 158°, 40 mins. Calculator told me to use 4qt boiling water at 198° boiling point. Resulting temp 152°
Rest 3 planned at 170° Instead I added about three quarts of boiling water (I'm estimating at this point) to bring the temp up to 160° and did not sparge.

I'm curious as to why the first calculation was so dead-on and the second so far off? Don't know if it's a flaw or an error on my part.

Cheers!

 

[LarryBrewer]

Re: Mash Calculator Issues

I have a feeling there is an issue with the 'infusion' aspect of the mash calculator. Been tracking it for awhile now, and this helps.

I'll incorporate your results into my records for further study.

When you did the initial strike, did you enter 30 as the grain/ambient temp? What temperature offset did you use, and what was the mash thickness?

At the point before the infusion for rest #2, did you measure the temp? It could have dropped some over the 30 minutes.

 

[Nosybear]

Re: Mash Calculator Issues

I measured the grain temps, as I'd taken them out of the freezer in my lagering fridge. 30° was it. And the mash had drifted down one degree to 144° before the second step.

 

[Nosybear]

Re: Mash Calculator Issues

Forgot to mention, I used the default 1.25 qt/lb for the mash thickness.

 

[Nosybear]

Re: Mash Calculator Issues

Aaand, I'll get all the questions answered eventually. I used zero for a temperature offset, as I always warm my mash tun to about 120° using hot water before mashing. My boiling temp was entered a degree lower than actual - 198° as opposed to 199° measured. Any problem was in calculating the second step, ending up a good 7° below target. Could it be that the calculator is somehow "forgetting" some of the mass from one step to the other? I was attempting to warm 7.75# of grain and 9.75 qt water 13° using water at 199°. Solving Palmer's equation:

Wa = (T2 - T1)(.2G + Wm)/(Tw - T2)

I only get 3.58 qt, 3.67 if I use 198 as boiling. Rounding up to 4 is probably a good measure. So now I have to look at my equipment to see if something maybe went wrong there, like I measured the temperature of the mash incorrectly or hit a "hot spot" with my measuring. Running through this diagnostic, I'd say the calculator worked correctly. Now it's time to look at home for the problem. Thanks!

 

[Nosybear]

Re: Mash Calculator Issues

Okay, last thoughts on this from me: Reflecting on yesterday while in the shower, I actually believe I made a measurement error. At the time I was brewing I was also working on dinner. I use a 2-qt measuring cup for large volumes of liquid (note to self - pick up a gallon measuring cup). Since the temperature change ended up about half of what I'd planned, Occam's Razor would lead me to think I used half the boiling water I should have, likely root cause: Distraction by something to do with dinner, likely grating cheese for topping Poblano Stew. As a result, I used two quarts of water vs. the required four, outcome, half the desired temperature change.

Sometimes I hate being an engineer.... ;-)

 

[LarryBrewer]

Re: Mash Calculator Issues

Good thoughts there, thanks for the update. I'll flag this one as possibly human error.

 

[LarryBrewer]

Re: (NEXT RELEASE) Mash Calculator Issues

The next release cleans up the mash calculator section in the brew feature:

Batch Sparge tab added
Fly Sparge tab added
Warnings related to exceeding freezing/boiling temp have been smoothed out.
Mash Calculator FAQ will be updated as well to explain how to use. Should be a lot more intuitive.

As for the figures being off, I've found it really comes down to ambient temp. Palmer's equations work very well at 68F, but need to be padded when temps are lower. The tabs have that info stated on them for some time, and since we posted that and updated the FAQ there have been zero inquiries on the subject.

 

[LarryBrewer]

The latest release, which is now live, smooths this the mash calculator section to a great degree! Enjoy!