temperature issue, is this common?

Hey all!

Well as my batch is boiling away. I'm struggling once again with my temps and yet.. i have no idea why. i'll explain the scenario, and let me know if you have any ideas or what i could do with this. 'cuz well, i'm lost!

This is a partial mash, 5 gallon batch.
3.5 lbs of grain for the mash

So, i put my thermometer in the pot and watched it go up to my mash temps (right around 160) turned the heat off my stove, and put it to the next burner (which was off), pulled the thermometer out and placed the bag into my pot, doughed in and stirred for a good 3-4 minutes to make sure all the grains were separated and not balled up, so after that, i put my thermometer back in the middle as far in as i can go without getting too close to the bottom (where it was when i was watching the temps) so it settled at 145, so i let it sit for 3-4 more minutes to just make sure everything will equalize in the pot. so it got to 146, so i turned on the heat a bit more, stirred alot and the termometer barely moved up, but the middle of the pot started boiling, so i pulled it back off the burner, threw cold water in and was fighting with the thermometer to show the correct temps and it seemed that even in a little over a gallon and a 1/2 of water, there were MAJOR cold spots all over the place.

What is the best way to get around this??

wow. a 1000 word sentence. got so confused i couldn't figure out the problem

Don't try to direct heat your mash tun. It just doesn't work very well and you will rubberband back and forth between being too hot and too cold. If you absolutely, positively need to heat it up on a burner, then use a very low flame and stir the heck out of your mash to keep the heat distributed evenly. But even then you are likely to overshoot your target.

I assume you're using a pot and maybe doing BIAB for the partial mash. If you've only got a few pounds of grain and you're just letting this thing sit on the stovetop or burner, you are probably losing heat pretty quickly through the sides and top. This is one of the reasons coolers make better mash tuns...they hold the heat in better. However, I have done BIAB partial mashes in my thin-walled aluminum pot. I just insulate it. I made an insulating wrapper using automotive firewall insulation, although I have seen people use the pipe/duct insulation you can get at Home Depot/Lowes/etc.

Also, IMO it is much easier to adjust down than to adjust up. So, I deliberately overshoot my strike water temp by 5-10 degrees, wrap the insulation around it, and then wait until I'm maybe 2-5 degrees over my target strike water temp. I will go ahead and mash in still a few degrees high. The insulation is going to absorb some of the heat in addition to the grain. If I am still over my target mash temp I will just stir it a bit more until the temp comes down. Usually it only takes a minute or two. Then I cover the pot and throw a folded towel or blanket or something on top (flame off!) to keep too much heat from escaping that way.

The most important thing after that is, DON'T OPEN IT UP. Every time you crack open your mash tun to check the temperature, you are losing heat. When I first started doing all grain I noticed that every time I opened up my cooler to check on it, the temperature was another degree or two (or three) lower. I finally figured out to leave it alone, and now my mashes lose at most one degree F over a 60 minute mash.

lumpher said:

wow. a 1000 word sentence. got so confused i couldn't figure out the problem

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I couldn't understand what you said because I didn't detect the beginning of a sentence. They usually start with capital letters.

I'm just giving you a hard time. Hopefully you didn't take it too seriously.

I don't have any issues with hitting my temps in a metal pot.

1. I use a strike temperature calculator (http://www.rackers.org/calcs.shtml) to determine the temp that the water needs to be before I add grain.

2. When I heat my strike water I always go over the temp by a few degrees and cut the flame. Do a good whirlpool with my spoon and I wait for the water to cool down to my strike temperature. By sticking the thermometer in and whirlpooling until the thermometer reads the temp you want; you are alleviating hot and cold spots by "mixing" them together.

3. Add grain. I may be off a degree or two (nothing needing "correction"), but usually I hit it spot on.

I have done several batches of AG with BIAB method. The first time I was having issues simular to what you mentioned.

I've tested temperatures and depending on how thick your mash is, you can end up with temperature gradients depending on where you measure and how deep you measure. A brief stir doesn't always level things out. I found that I had to kind of fold the mash. Stir and try to bring the bottom mash to the top and then stir it around. That balanced things out for me.

Also, if you find that you need to add heat, don't just light up the burner and wait for the temperature to change. By the time you do see a change the temperature of the mash at the bottom blows right by what you are trying to achieve.

If I find that I don't hit the temperature I want and I'm low, I light the burner and constantly stir. I only turn the burner on for 10 or 20 seconds at a time. Keep stiring and measure. You can creap up on the temp you want more accurately.

If you are slightly high, you can add a splash of water but leave the cover off and stir rapidly to release the heat. This works well for me.

I had the same thing going on my first time. Add heat. Dam, overshot big. Add water. Undershot. Add heat etc.

If I'm within a deg or so I call it good and wrap a sleeping bag around it and go upstairs and grab a beer and watch TV for a hour or so. I don't even look any more as it will hold a degree for a 90 min mash properly wrapped.

and after your post, i now know exactly where i also went wrong....
while i was thinking one issue, i deff did NOT have my temps up correctly so it was either teh strike temp (which i was 10* off ) or a combination of both.
(but im' better on strike 'cuz i was so far off)
i'll remember this and keep it on a check list!
thanks guys!

@RukusDM -
That is going to be some valuable information as well from the patience aspect, as a new home brewer i think i'm just too KEEN on having it be the correct temperature. But as i've heard everyone say, grains are forgiving to a point, so i have to keep remembering that as well

i love this board!

Rivenin said:

@RukusDM -
That is going to be some valuable information as well from the patience aspect, as a new home brewer i think i'm just too KEEN on having it be the correct temperature. But as i've heard everyone say, grains are forgiving to a point, so i have to keep remembering that as well

i love this board!

Click to expand...

Yeah, patience is hard when your so excited about the process. Took me a while to calm down. I was checking the temperatures every few min. Actually lost more heat opening up and testing than it was worth. Just let her ride when you get close. Try to nail it but if you cant get it sorted within 5 or 10 min, average it out and let it go. You'll do better next time as you will know more about your strike temperature requirement.

I also had a really hard time waiting for fermenting and then bottle conditioning. Now I have a bunch of batches under my belt, I hardly even look at the fermenter for 2 weeks.

I was bottling too soon as well. I have 12 gallons that I made around christmas that I havn't bottled from secondary yet either.