# 2nd batch sparge water temp calculation

Discussion in 'General Brewing Discussions' started by sbaclimber, Oct 13, 2012.

1. ### sbaclimber Well-Known Member

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#1
Up until my last brew (10x all grain IPA brews), I have only used single-run batch sparges (mash-out->drain->add hot water->wait->drain), and through experience have been able to dial-in my sparge water temperature. (alternately, by now knowing my mash tun heat loss, can use the Mash Calculator to calculate varying strike water vs grain volumes)

My latest brew will hopefully become a barley wine and is my first *higher* gravity beer (OG = 1.086), which is indirectly the cause of some of the difficulty I had while brewing yesterday evening.
Due to limited mash tun space (~30l. total volume), I decided on a 2:1 H2O-grain ratio and 2 batch sparges to achieve my goal of ~20l. of wort @1.085-1.090 SG.
9.2kg of grain + 18.4l. strike water = mash tun @ just under capacity + mash temp @ 67°C (so far so good!)
1st sparge w/ 9.2l. of boiling water = mash tun @ capacity + sparge temp @ 73°C (bit low, but acceptable. Sparge water hotter than 100°C isn't possible, and more than 9.2l. won't fit in my mash tun)
...now comes problem...
2nd sparge w/ 9.2l. of H2O @ 85°C = mash tun @ just under capacity + sparge temp @ 74°C!!

I would like to have had a sparge temp closer to 78-80°C, but had no way of calculating the temperature for 9.2l. of sparge water ahead of time. The Mash and Infusion Calculators here only calculate Xl. of H2O @ 100°C, not Xl. of H2O @ Y°C, where X is variable but pre-defined.

I probably just missed it while searching, but does anyone know of a way to calculate the temperature of X amount of water needed to raise Y amount of mash(grain+water) Z degrees?
e.g. I had 9.2kg grain + 13l. H2O (absorbed in the grain, of course) in my mash tun @ 73°C, and needed to add 9.2l. H2O to raise the temp to 78°C. What temperature should the 2nd 9.2l. H2O have been?

PS, the good news is...I ended up with 23l. of wort (actually recovered more than expected) @ an SG of 1.086, so I am pretty stoked that everything worked out regardless of temp, and I even achieved my best brew house efficiency to date.

2. ### LarryBrewer Active Member

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#2
If you do a brew session, then go to the mash calculator tab, then the 'infuse' tab on the left, you can specify current temperature, target temperature, and infusion amount. The system will then calculate the required temperature. Give that a shot and let us know if it does what you want.

3. ### sbaclimber Well-Known Member

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#3
Hey Larry,

thanks for pointing me to the Mash Calculator in the Brew Session tool. I didn't think to look there...

I gave it a go, and with some fiddling was sort of successful, but not really.
I think the problem is, is that the calculator doesn't really allow for multiple drainings / batch sparges of varying volumes. I tried inserting a "drain to kettle" between my "strike" and "infusion" but even thought the volumes weren't all that far off, the temps didn't line up at all. Without a "drain to kettle", neither the volumes nor the temps fit. :cry:
Here are the water requirements, the mash water volume = strike(18.4l.) + sparge#1(9.2l.) + sparge#2(9.2l.):

I don't really do a proper mash-out (raising temp, etc), I simply drain the mash tun.
In this case, I recovered ~5.5l of wort, leaving me with a volume of ~13l. H2O + 9.2kg grain still in the mash tun.
Obviously, the calculator doesn't support multiple interim drainings, but for some reason, I can't even trick it into properly calculating the temperature of an infusion for this remaining *thick* mash.
e.g. I tried tweaking the strike values to create a virtual thick mash after the first draining. Then I added an infusion to simulate raising the temperature from 65°C (I assumed a couple degree temp loss during the first drain) to 73°C with the 9.2l. H2O for the first sparge:

I then did the same thing to simulate the second sparge:

Both sparge water temps are rather low. As I already mentioned, my 1st sparge addition was boiling, and barely got the thick post-drain mash up to 74°C.

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4. ### LarryBrewer Active Member

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#4
Did you try:
Strike -> Drain -> Infuse -> Drain -> Infuse -> Drain ?

That would be the way to do it. I'd be interested to know specifics on how the temps were off, and by how much? Please re-simulate it if you are still interested in working it out and we'll see if we can improve anything on this end. Recently the simple equation powering the mash calculator has come under some scrutiny. We are looking at alternatives.

For some background - the infuse tab looks at the current mash volume. When there is fluid in the mash tun, the infuse logic takes this into account. More wort in the mash tun means it takes more energy for the temperature to budge. That's why you were having better luck using the 'drain to kettle' option in between infusions, since that is the process you were doing. When there is no fluid in the mash tun, the infuse logic uses the same equation as the strike tab to calculate the temps (and it defaults the grain temperature to whatever the last temperature of the mash was, but you can adjust it).

Hitting temperature exactly is pretty tough, would require all thermometers to be calibrated, and you have to move fast and stir well because everything is cooling off constantly. Right now, I'd say to keep some boiling water, and cold water on hand to make minor adjustments (half Liter at a time).

The next release will include an upgrade that will let you infuse a colder temperature of water to bring down temps if you over shoot. We are also going to beef up the FAQ on this section as well.

5. ### sbaclimber Well-Known Member

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#5
I did try adding Drains between infusions, but couldn't remember in what order, so I ran a new simulation.
The volumes of water, strike and infusion water temps, and target temps are all exactly what I had in my actual brew session.
Because I did not exactly record my mash temps right before adding my infusions, I tweaked those in the simulation to get the infusion water temps to match the ones I actually had in my session.
The red marked mash temps below are the tweaked ones. Obviously there is no possible way my post-drain-pre-infusion mash was as cold as 9°C, and even 47°C seems unrealistically low...

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6. ### LarryBrewer Active Member

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#6
On the very first go around, you were infusing without doing the drain steps. The calculator would indeed tell you higher infusion temps because it thinks the mash tun had 18.4 L in it. It takes high temperatures to heat a relatively large amount of water (18.4L) by several degrees, with a relatively small amount of water (9.2L). So I would not worry about those numbers.

I'm fiddling with a mock recipe and brew session similar to yours. The volumes are not exactly the same as yours, but here is how I went about it, and this is how I would expect it to look.

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7. ### sbaclimber Well-Known Member

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#7
...then there is something seriously wrong with my set-up.
In my actual real-life brewing session, at #1, I had to add 9.2l. of boiling water to hit 73°C, and at #2 9.2l. at 85°C to hit 74°C.

Could it have something to do with how much wort I am actually able to drain into the pot?
As you can see from our screenshots, I had 36.8l. of mash water of which 26.6l. ended up in the pot (very close to the actual 27l. I ended up with), where as you calculated 34.1l. of mash water and 27.5l. in the pot.
We have a difference of almost 4l. in grain absorption and mash tun dead space...could that be it?

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8. ### LarryBrewer Active Member

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#8
My batch and equipment profile was using made up numbers, so don't worry about comparing that. Yes the difference was in grain absorption (my profile is set to US units, which is why that was off by so much).

-> had to add 9.2l. of boiling water to hit 73°C

That sounds really high. You were pouring this boiling water into a drained mash tun, that was at 67 a few minutes ago, and it only got to 73? The number makes more sense if you do just the strike, no drain, then look at the Add Boiling tab, and set the current temp to 61. (see attachment) I wonder if the temperature just drifted down over time?

-> at #2 9.2l. at 85°C to hit 74°C -> that sounds a little more reasonable

Sorry this didn't go as smoothly as you expected. Another brewer had his strike temperate about 5+ degrees higher than expected, which we are discussing here: viewtopic.php?f=3&t=186 I bet you two are using very different processes and equipment. The equation just can't deal with all that variation. The strike equation works well for me personally, but I have never tried a triple sparge.

When mashing, expect that small temperature adjustments will need to take place when doing infusions. That said, they should not be wildly off. In the medium term I expect us to revisit the equations behind the mash calculator.

One thing - check the calibration on your thermometers. I found my digital unit was out of whack after sitting for awhile.

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9. ### sbaclimber Well-Known Member

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#9
Definitely a good call. I have had one instance in the past where the same thing happened to me.
I am fairly sure my thermometer wasn't off during this particular session though.

I think you are right about the temperature drifting quite a bit lower than I expected, but that alone probably isn't my problem.
I will have a closer look at the strike temp discussion thread, and have a play with some formulas to see if I can come up with one that works for my set-up.
Previous to the last session, where I first became aware of the incompatibility between my set-up and the mash calculator, I had brewed the exact(volume-wise) same recipe 4x in a row with only minor temperature differences (1-2°) and consistent results. So, at least I have a reliable base-line to start with.
I will post up if I come up with anything useful.

10. ### sbaclimber Well-Known Member

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#10
Update:
After playing around a bit, I have come up with 2 interesting (for me) facts about my set-up.
1) between draining the tun the first time and measure my (batch) sparge temp, I lose about 7°C (+-1°). After the second drain and filling up for the 2nd sparge, somewhat less (~5°). I will need to brew some different recipes / sized batches / #s of sparges / etc, in order to come up with a reliable formula though.
2) my thermometer is definitely off. :cry:
I just tested it against a digital fever thermometer in the ~30°C range, where it was off by almost +4°, and with boiling water, where it was off by about -5° (assuming boiling is actually 100°C here at 110m elevation).
So, who knows what temps my last few mashes/sparges have had... :roll:

11. ### adant33 New Member

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#11
Sorry to revive an old thread...

I'm trying to calculate the temp I need to batch sparge... On the Batch Sparge tab - it has an amount input and temp, but it doesn't indicate what temp I need to heat the water too (to achieve the sparge temp). I know there is the infusion tab, but does this take into account the fact that I've already drained my wort and there is much less thermal mass?

Thanks!

12. ### Nosybear Well-Known Member

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#12
Don't worry about it too much. As long as you keep the final temperature below 175 degrees F, you should be fine. I usually heat my sparge water to 175 and let the temperature fall where it will. There's little danger of extracting tannins when batch sparging so this is a RDWHAHB situation.

13. ### Ozarks Mountain Brew Moderator Staff Member

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#13
yeah some say boil the water just to bring the grain up to 170 and some say just keep the wort at 170 and I say when batch sparging your really just washing sugar off the outside of the grain and temperature really doesn't matter

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