Understanding my temperature variations

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Understanding my temperature variations

Postby kevponce » Sat Jun 06, 2009 5:30 pm

I finally brewed an all-grain using BTP and have some questions regarding temperatures. First the water volumes were dead nuts all the way through so that was a great help, but here are some temp questions.

First some quick background. I had noticed after doing about 6 partial mashes that to get to about 152˚ I needed to heat my water(liquor) to 170˚ or so. Then by the time I put it in my tun it was about 166˚ or so. Si I calibrated my mash tun and after setting the target for 152˚ the strike was 166˚. So I was a little skeptical and heated the water to 170˚, then I also preheated my tun with about 1.5 gallons of hot tap water. So I put the water in the tun it settled to 166˚ I then added the grain at 67˚ and it stabilized way high at 156.5˚. I added a little cold water to bring it down. But my BTP estimated, calculated temps were all off and right down the schedule I had to keep changing things, but they are all linked together so It was confusing trying to document what was really happening temp wise.

So question 1. How do you edit BTP temps to document what is really happening? What is the rest calibration yield sign that keeps popping up and how does it work? What does the heat output slider do in the editors? And where do you put in a small addition of water to the mash to cool it?

Any help is appreciated?
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Re: Understanding my temperature variations

Postby slothrob » Sun Jun 07, 2009 9:23 am

kevponce wrote: Si I calibrated my mash tun and after setting the target for 152˚ the strike was 166˚.
These numbers look like you didn't select the calibrated tun as the Mash Vessel or didn't select a Heating Vessel, which will assume you have a heated tun. In the latter case, it displays the temperature that you heat the water to within the tun. That negates the calculation for the heat absorbed by the cold tun, to answer your question from the other thread.

166°F was probably the calculated temperature that the water in the tun should be before adding the grain.

I think the reason you then overshot the strike temperature, based on personal experience, is that you also pre-heated your tun. The calibration took the loss of heat to the cold tun into account, then you negated that loss. In fact, if you're like me, you probably used hotter water than your strike to pre-heat your tun, which might have pre-loaded some extra heat into that thermal mass that later transferred to the mash, if I understand what's going on there.

kevponce wrote:So question 1. How do you edit BTP temps to document what is really happening? What does the heat output slider do in the editors? And where do you put in a small addition of water to the mash to cool it?

I can answer a couple questions:
You can edit the target temps to represent your actual mash temps, but it will list unreal infusion temps. You'll need to record that in the Notes, or try changing the vessel calibration to make them work. I wouldn't do that latter with the pre-heated tun values, though.

The heat output slider adjusts how hot you have your burner set, changing the time it takes to hit your temp.

The small additions would qualify as Infusions, so you need to add an additional Infusion step after the Mash In.
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