Why is my temp climbing?

[jcarson83]

I'm shooting for my second AG this weekend and I've got a little problem I need to work out. For some reason on my last one my temp kept climbing for an hour, the whole mash. I have one of those new 6 gal blue igloos for a tun and used about 12lbs of grain. I just dumped the water in on top of the grains, didn't stir at first, and closed the lid. Being the first AG I didn realize how long it takes for the air to leave the grains, so after about 10 min I gave it a good stir and thats when the temp started to rise. It went from about 148 to 165 in about an hour. My therm is long enough to reach at least a third of the way down the cooler and the its completely full of mash.

It didn't turn out bad at all, 75% efficiency, but I was hoping to mash my next one at around 158.

batch sparge.

It doens't make any sense to me. The temperature should drop if anything as long as I got a good mix.

Oh and the strike was 175 due to the fact that I forgot to preheat the tun and was trying to compensate.

 

[G. Cretin]

wild guess in 3 2 1. I'm totaly guessing it would be the chemical reaction of the enzymes breaking carbs down to sugars. All chemical reactions give of energy in one form or another so in this case I think it was heat and in a new cooler with proper sealing and insulation thats what makes sense to me.

 

[Sir Sudster]

If it settled out at 165 then you where way off on your strike temp.

When you mash in stir well . You should see your constant with in minutes.

My suggestion is to pour your water in before the grains at about 3-5 degrees above what you are trying to hit. Then add your grains and stir well . You should be in the range of 1.25-1.5 quarts h2o /lb grain with the strike water.

better luck next time.

 

[user 574]

175 is a high strike. Use ProMash (my recommendation) or other to calc strike temp but it only gets you to 90% IMO. Like Suds said, stir well. Also, have some near boiling and some ice water on hand to get it where you want it. I was told you have 5min before you should stop screwing around with the mash so get it where you want it within this time window. Your fluctuation seems to be related to lack of stir...

 

[Exo]

My "guess" is that your thermometer was stuck into some grains that weren't wet...a dry spot. Water, then pour your grains in while stirring. It's two-handed hell but should be done. Called "doughing in".

Think of your grains as flour...better to stir flour into water than water into flour.

 

[NotionCommotion]

I second the inadaquate mixture theory. Also try taking temperature readings from various locations in your mash periodically.