Variation in grain bed temperature

[cbird01]

I am trying to diagnose if I have a bad thermometer for the job of checking water and mash temperatures. When I am bringing water to temp before mashing, the temperature is very even. When I am checking the temp of my grain bed, it is all over the place - like +/- 5 degree swing as I move from place to place in the grain bed. I do not take any readings until I have really stirred the grain bed after water addition for about 3 minutes.

Is this normal? If it is, how do you get accurate grain bed temps?

Here is my new thermometer http://www.oxo.com/OA_HTML/xxoxo_ibeCCtpOXOPrdDtl.jsp?a=b&item=79452&section=10062 $40

 

[TipsyDragon]

did you calibrate your thermometer? did you preheat your mash tun?

right off hand i would say you need to stir more. make sure you stir ALL the grain. the temperature will eventually equalize. check the temps ever 15-20 minutes and add more water as necessary.

 

[cbird01]

I did not calibrate my thermometer...but that would just effect getting an accurate measurement not an inconsistent one (although I should do this)

I did preheat my mash tun.

I have a rectangle copper manifold in my MLT and I even am sure to stir the grain out between each row of copper and between it and the cooler sides.

So you don't think it could be a thermometer error. I will try and stir for longer and keep monitoring. Just don't want the lid open too long.

 

[permo]

you are having a very similar problem that i had right away when I moved to all grain.

First of all you need to really stir the grains, get rid of all the clumps and pockets of dry grain. Then let the mash proceed for a few minutes with the lid closed. Then you can open the lid after 2-3 minutes and take a reading.

You will still have variations in temperature in the grain bed, i would consider taking readings from the the top 1/2 of the grain bed because heat rises when you open the lid..this heat will destribute and be trapped in when you close the lid.

 

[shataway]

I do not take any readings until I have really stirred the grain bed after water addition for about 3 minutes.

How are you preheating if you are adding water to the grains?

If the center of the grain bed is hotter than the sides, I think you may be losing temp to the cooler. Suggest you preheat with your strike water (+12 deg) for 10 min then add your grains.

How does you temp hold over the 60 min mash? Within 2 deg?

 

[wildwest450]

You will get variations as the grain sits. I check my temp by stirring the grains around the thermometer. Or swirl the thermometer around the mash, you will get an "average" number.

 

[david_42]

Make a thinner mash, 5:1 (by weight) or higher. Thick mashes are difficult to stir properly and more water means better thermal stability.