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andreiz · 01-28-2009, 10:17 PM

So I've done a couple of partial mashes now, following Deathbrewer's stove-top method (using the kettle as a mash tun), but have encountered some weirdness with the temperature stability. For example, the recipe called for 155° mash temp, so I heated up water to 167° (because of 11-12° loss). I added the grains, stirred thoroughly and checked temp with the floating thermometer, which showed 156° or so. I left the thermometer in, put the lid on and wrapped it in a towel. Came back 10 mins later to check, and the temp was into mid 160s, so I added a bit of cold water stirred again, etc., but on next check the temp was up again. Any idea why this might be happening? I'm pretty sure laws of thermodynamics don't allow this unless the amylase enzymatic reaction releases heat.

***Yooper*** · 01-28-2009, 10:20 PM

Was the burner still hot? Did you stir well, and check it again in a couple of minutes? It usually takes about 5 minutes for the temperature to stabilize after mixing it up.

andreiz · 01-28-2009, 10:42 PM

Quote:

Originally Posted by YooperBrew

Was the burner still hot? Did you stir well, and check it again in a couple of minutes? It usually takes about 5 minutes for the temperature to stabilize after mixing it up.

No, burner wasn't hot. Also, this happened more than once in the first 20 mins of mashing, i.e. check that the temp is in range, put lid on, etc come back later - temp is up.

***Yooper*** · 01-28-2009, 10:58 PM

Quote:

Originally Posted by andreiz

No, burner wasn't hot. Also, this happened more than once in the first 20 mins of mashing, i.e. check that the temp is in range, put lid on, etc come back later - temp is up.

Maybe the pot is hot, and the heat is transferring to the mash? I don't know, but without heat applied, the temperature can't rise.

Beernewb · 01-29-2009, 11:18 AM

it's the lid...

the heat has nowhere to escape...especially if there isn't any headroom.

carl spakler · 01-29-2009, 11:21 AM

Did you take the pot off the stove altogether? The residual heat from the heating element (electric) or grate (gas) may be enough to boost the temp a few degrees. The other possibility is you didn't mix the mash well enough and hit a cool spot with your thermometer.

If you mixed well and are adding no heat you will not see any temp increase...at least in this world.

I do PM on my stove and have had good luck with consistent temps. My technique:
Heat strike water
Turn oven to lowest setting (170*), when it is preheated shut it off
Add grains and stir, stir, stir, stir to get the whole grainy mess uniform
Check mash temp and adjust if needed
Put a lid on the pot and put it in the warm oven and leave it alone
I *might* stir part way through, but not always.
My mash typically comes out at the same temp it goes in the oven at +/- 1 degree

JamjaPA · 01-29-2009, 11:36 AM

i have noticed this also if i bring the strike water up to temp fast and do not let it stabalize at 165 or so before i add the grains.

if i heat it up quickly and as soon as it hits temp, turn off heat, throw in grains, and cover, i experience the same thing.

it seems better to bring the water up to temp and let it stabalize for a couple minutes. i have done exactly what deathbrewer describes and kept temp within a degree or two for over 60 minutes.

Brewme · 01-29-2009, 05:19 PM

I have had problems with stablizing my temp as well during the first 30 minutes or so, but I have never waited for the strike water to stablize. I will have to try that.

Also, it seems that my mash is always very thick when I follow the guidlines from the Clone Brews book. Should the consistency be of thick oatmeal?

LeeF · 01-29-2009, 05:48 PM

I was about to explain and realized a link would be better.
THE DYNAMIC RESPONSE OF MEASURING INSTRUMENTS

Look at the first order graph about half way down the page. Your thermometer reading will rise/drop fast and start to slow as it approaches the actual temp of the fluid.

If you want to 'dial in' your thermometer I would recommend calibrating using a pot of boiling water and a cup of ice water. Place in the ice water for many minutes and let the thermometer read approx. 32F. Move thermometer to the boiling water. You can time or just count to 20 or 30 seconds. Take reading and subtract from 212F. This should be a good approx. of how far off your reading is at 20 or 30 seconds at any temp. Do it from boiling to ice bath just to verify the first. You can also try this at 150F and see how it differs.

Lee

**Schlenkerla** · 01-29-2009, 05:54 PM

Quote:

Originally Posted by carl spakler

Did you take the pot off the stove altogether? The residual heat from the heating element (electric) or grate (gas) may be enough to boost the temp a few degrees. The other possibility is you didn't mix the mash well enough and hit a cool spot with your thermometer.

If you mixed well and are adding no heat you will not see any temp increase...at least in this world.

I do PM on my stove and have had good luck with consistent temps. My technique:
Heat strike water
Turn oven to lowest setting (170*), when it is preheated shut it off
Add grains and stir, stir, stir, stir to get the whole grainy mess uniform
Check mash temp and adjust if needed
Put a lid on the pot and put it in the warm oven and leave it alone
I *might* stir part way through, but not always.
My mash typically comes out at the same temp it goes in the oven at +/- 1 degree

Do you see a temperature rise at a prolonged soak at 170F?

When I partial mash I target a recipe for 4lbs grain to be mashed in a 2 gal igloo Cooler fitted with a veggie strainer for a false bottom. I usually will do single infusions but if I step I add measured amounts of boiled water. My cooler was purchased from wal-mart for $8.00