Mash Tun Calibration

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bpylant
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Mash Tun Calibration

Post by bpylant »

I mash in a rectangular cooler, and while I've never had any issues hitting my mash temps I'd like to calibrate the thermal transfer coefficient.

My mash-in method is to add all of my strike water to the cooler at about 180-190ºF, close the lid and let it sit for 5-10 minutes or so while I do other things, then take the lid off and wait for it to drop to strike temperature (for me, usually around 169ºF or thereabouts).

To properly calculate my coefficient and heat capacity values, should I follow this same method or should I be adding the measured, heated water to the cooler without preheating the cooler first? I'm thinking the latter, even though that is not my actual mash-in method, but I wanted to check with folks who know a lot more about this than I do.

Thanks!
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Re: Mash Tun Calibration

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Start from room temperature. The advantage in starting with a room temperature mash tun is that it will measure the heat required to bring the tun up to temperature, so you don't have to pre-heat the tun. Or, if you prefer to add the water and let it heat the tun before adding the grain, it should give you the temperature of the water that you should add so that it will stabilize at the temperature that will hit your mash temperature once the grain is added. That should remove the step of waiting for the water temperature to drop before adding the grain.

I used the conventional calibration procedure for my tun, but, for a while, I liked to pre-heat my tun much like you do. The way I did that was to duplicate the tun, in the equipment window, then create a second one the had a heat capacity of "0" (by typing the "temperature after 5 min" into the "infusion temp." field), then naming it "Tun - pre-heated". That will (should) predict, in the schedule, the temperature that you want the water in the tun to stabilize at, before you add the grain, if you use the strike water to pre-heat the tun.

Minor edit: to clarify which data fields to which I was referring.
Last edited by slothrob on Sat Apr 13, 2013 1:32 pm, edited 1 time in total.
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bpylant
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Re: Mash Tun Calibration

Post by bpylant »

Excellent, thanks for the advice! It's a beautiful day today, so I think I'm going to spend the next couple of hours calibrating my vessels and heat sources.

Viva la science!
:)
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Re: Mash Tun Calibration

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Good luck and enjoy the weather!
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Re: Mash Tun Calibration

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Seemed to work out. For my mash tun, I started with 4 gallons @ 169ºF. At 5 minutes it was 165F, and at 65 minutes it was 152ºF. This worked out to a heat capacity of 2663.8 J/K, and a transfer coef. of 3.14 W/m2 K.

For the burner under my HLT, I recorded the following heating times:

80º - 98ºF: 2:56.7
98º - 116ºF: 2:58.3
116º - 134ºF: 2:49.7
134º - 152ºF: 3:05
152º - 170ºF: 3:06.5

So I averaged it all out to 3 minutes to heat 18ºF, which gave me a heat xfer of 5.272 kW. I did not calibrate the heat capacity or transfer coef. of the HLT itself, or the boil kettle. Maybe I'll get to that later, but I'm not sure it's really necessary for my simple 5 gallon batch-sparge batches. (Feel free to tell me I'm wrong on that!)

Now to figure out how the schedule (and its various steps) works...
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Re: Mash Tun Calibration

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bpylant wrote:I did not calibrate the heat capacity or transfer coef. of the HLT itself, or the boil kettle. Maybe I'll get to that later, but I'm not sure it's really necessary for my simple 5 gallon batch-sparge batches. (Feel free to tell me I'm wrong on that!)

Now to figure out how the schedule (and its various steps) works...
There could be reasons to calibrate them, like predicting loss of temperature in the HLT or time from runoff to boil, but they aren't needed for the schedule to work.

The schedule is a powerful tool, which means that it can have some complexities that you'll need to master. We can help with that here.

I'd start by adding in all the steps you'll need for your batch, in the correct order. For a simple Batch Sparge, that would be at least a Mash In, a Rest , and a Batch Sparge. In the Mash In window, set your desired Thickness and Final Temperature (your mash temperature), and BTP should do the rest. In the Rest window, set the Duration. In the Batch Sparge window, check the Lock box next to Total Runoff and set the Collection Vessel to None, then it will calculate your sparge volume and also calculate the sparge liquor temperature that you want based on the target temperature you set in Final Temp.
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Re: Mash Tun Calibration

Post by bpylant »

Cool, thanks!

I set it up and the numbers all look right. (I did set up two sparges, for the initial runoff and then the batch sparge. Was this right?)

I am a little confused, though: why set the collection vessel to 'none' as opposed to my boil kettle?

Here's a screenshot (which isn't showing the full width, here's the direct URL: http://brewdrinkrepeat.com/forum_pix/BTP_schedule_1.png )


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Re: Mash Tun Calibration

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bpylant wrote:Cool, thanks!

I set it up and the numbers all look right. (I did set up two sparges, for the initial runoff and then the batch sparge. Was this right?)
That's right. I would only call the second one a sparge, but that's quibbling. First and second runnings or first runnings and sparge is what I would usually call them, to try and avoid confusion, since some brewers actually do two sparges (meaning they take three runnings).
I am a little confused, though: why set the collection vessel to 'none' as opposed to my boil kettle?
Choosing the collection vessel will tell you what the temperature will be of the liquid once it has all been collected into the kettle, which can be useful for calculating how long it will take to hit the boil from the end of the mash.

Choosing "none" calculates the temperature in the tun, after adding the sparge liquor. If you just add 170F sparge water (or whatever temperature you like to add), it doesn't matter. However, if you like to have the grain and sparge hit a certain temperature in the tun, choosing "none" should help you to predict how to get there.
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Re: Mash Tun Calibration

Post by bpylant »

Brewed last night and everything seemed to work; it predicted my strike temperature correctly, as well as my sparge volumes. I'll probably have some more questions as I go to improve my settings, but thanks so much for pointing me in the right direction!

I did rename the first to runoff, but it is correct to use the Batch Sparge dialog for both the first runoff and the batch sparge, correct?

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Re: Mash Tun Calibration

Post by slothrob »

bpylant wrote: I did rename the first to runoff, but it is correct to use the Batch Sparge dialog for both the first runoff and the batch sparge, correct?
That's a good way to do it.

I'm glad the calibration worked so well. It can really streamline the process when you have reliable temperature predictions.
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Re: Mash Tun Calibration

Post by bpylant »

Thanks... I've been using BTP since it was first released for recipe formulation, but I'm only now looking to use it to its fullest potential on the "sciencey side" of things. Clearly a LOT of power here, I just need to learn how to harness it all. Come on, brains, get working! :D
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