Mashing temperature: variable throughout vessel

[Sea brewer]

Hi All

Am I over thinking this? I aim for a mash of 66oC plus or minus 2oC. This is for BIAB. Using my thermometer stick I get very different readings around my vessel which is a plastic Peco immersion heater. I stir it vigorously and for a few minutes the temperature seems more uniform. But quickly the variations set in, +/-10oC depending on where I take the reading from. Is this is a problem and how do others ensure consistent temps?

thanks
Seabrewer

 

[NIGHTSKY BREWING]

Yes is a bit of a problem.... As heat rise,s this is the hottest part of the mash Tun....if you can recirculate the mash with a pump you can get a more even temperature..... But on cold days like today l bet the walls of a given mash tun will be a bit colder.

But think about if you cannot recirculate ???? Would the bottom mash at 63/4 deg and the top at 65/66deg......which would make a balanced Wort.???

I pre heat mast tun and underlet.....keep DO O2 down. Alu Foil on the top

 

[Clint]

I use a picnic cooler. I've calculated that my water temp needs to be around 78c for room temp grain and cooler to get a mash temp of 65/66. If I'm bringing the tun in from cold temps I pre heat it with some hot water and leave the lid down for a bit,better still fetch it in the night before. I don't recirculate the mash and do stir a couple of times during. I do check the temp after mashing in and if its wildly out I adjust as req with hot or cold. You'll always get temp anomaly in a non circulated mash I recon. FWIW in the summer I leave the cooler as it is in the winter I sometimes chuck the dogs blanket over it or the Mrs best coat but seeing as I'm inside I don't suppose it makes a difference!

 

[Twostage]

Don't forget the heating element will retain some heat which will create a hot spot too. Realistically, though, the enzymes work over a temperature range (bell curve I would think) so a couple of degrees is probably not make or break.

I use towels and old curtains wrapped around whatever I've chosen to be the mash vessel and make the assumption that it is going to drop a few degrees during the mash.

 

[Agentgonzo]

As heat rise,s this is the hottest part of the mash Tun

Sorry, but this is a common misconception. "Heat" does not rise. If you get a hot metal bar, the heat will not rise to the top.

Hot liquids/gasses will rise due to convection. But your mash is thick enough that you won't get convection currents. So the top of the mash will not get hotter "because heat rises" (because it doesn't).

What you will find will happen is that the edges/top/bottom of your mash will be cooler than the centre as the periphery will lose heat to the surroundings and cool, whereas the centre will retain heat because it is being kept hot by the rest of the mash. The only way for the centre of the mash to lose heat is to conduct it to the rest of the mash.

If you are finding that the top of the mash is hotter than the bottom, the two most likely explanations are that the bottom is being cooled by conduction to the worktop that it is sitting on. Or most likely that you as you filled the mash tun, the first water that went in got cooled by the cold grain/mash tun and the first water in is also at the bottom (gravity) - the last water into the mash tun (at the top) won't get cooled as much as the first - you need to do a LOT of mixing to evenly distribute the heat at dough in and stirring round and round doesn't necessarily do this (you need to stir up and down as well).

Sorry. Science rant over

 

[Clint]

During the summer my little beer shed is hot near the roof but cool near the floor. Why?

 

[Agentgonzo]

During the summer my little beer shed is hot near the roof but cool near the floor. Why?

Clint, not sure whether you're taking the **** or not

Hot liquids/gasses will rise due to convection

 

[Rodcx500z]

During the summer my little beer shed is hot near the roof but cool near the floor. Why?

The roof is nearer the sun

 

[Clint]

Clint, not sure whether you're taking the **** or not

It is though. Plus I store beers on the floor in there during tge summer as it keeps them cool.

 

[Agentgonzo]

It is though. Plus I store beers on the floor in there during tge summer as it keeps them cool.

I'm not doubting the fact that the shed is like that.

Ground is cold (comparatively).
Sun beats down on the hot roof. Hot roof heats air at the top. Hot air at the top stays above the cold air at the bottom (as it's less dense so "floats" on the cooler air)

 

[Sea brewer]

Sorry, but this is a common misconception. "Heat" does not rise. If you get a hot metal bar, the heat will not rise to the top.

Hot liquids/gasses will rise due to convection. But your mash is thick enough that you won't get convection currents. So the top of the mash will not get hotter "because heat rises" (because it doesn't).

What you will find will happen is that the edges/top/bottom of your mash will be cooler than the centre as the periphery will lose heat to the surroundings and cool, whereas the centre will retain heat because it is being kept hot by the rest of the mash. The only way for the centre of the mash to lose heat is to conduct it to the rest of the mash.

If you are finding that the top of the mash is hotter than the bottom, the two most likely explanations are that the bottom is being cooled by conduction to the worktop that it is sitting on. Or most likely that you as you filled the mash tun, the first water that went in got cooled by the cold grain/mash tun and the first water in is also at the bottom (gravity) - the last water into the mash tun (at the top) won't get cooled as much as the first - you need to do a LOT of mixing to evenly distribute the heat at dough in and stirring round and round doesn't necessarily do this (you need to stir up and down as well).

Sorry. Science rant over

Thanks, also a scientist so I get it. My temps are cooler on top but up to 10oC hotter in the middle. And on the side of the heater with the element it is even higher. I’m trying not to overthink this as home brewing is meant to be my time away from my job so am tempted to just ignore it and declare it an art

 

[MashBag]

Insulation insulation and then if you have space insulation.

So much easier, quicker and more reliable.

 

[hoppyscotty]

I think if you are going to employ heating through the mash then you need to recirculate so you get regular mixing of the wort through the volume of the mash. If you're not going to recirculate then you're just better off using a well insulated mash tun and mashing in that with no heating element., There are very good calculators where you input the ambient temp (temp of grain) temp of water and volume and will calculate the tempo your strike water such that it cools down during mash in and evens out at the target strike temp. I've found these calculators (specifically the one on brewers friend) to be pretty good. If you don't have recirculation then you could maintain heating through he mash and continuously stir to ensure heat is evenly distributed.

 

[MashBag]

..... if you are going to employ heating through the mash then you need to recirculate so you get regular mixing of the wort....

Absolutely. Yup, both or neither