How to measure BIAB temps?

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Vintage Iron

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I had a question on my mash temps for BIAB.

Normal process is to heat to 160deg and drop in the bag, then mash-in the grains. The question I have is, where should I be measuring temp? After 5mins of vigorous stirring, the mash itself is in the upper 140's, while the liquid outside the bag is at about 154deg. (Shooting for a 152* mash temp)

Could the HD 5-gal paint strainer bags I'm using, be a bit too small for my kettle and causing this temp stratification? When full of grains, the bag easily touches the bottom of the kettle, but there is about 1.5" of space all the way around the sides.

I'm curious to hear your thoughts on this.
 
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Oginme

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If you can easily measure the temperature of the water outside of the grain bag, it is probably too small.

My method (using a custom made bag) is to mix the grains into the strike water slowly while stirring. Then I mix/stir/agitate the mash vigorously for 10 minutes, making sure to stir up grains from the bottom to the top and checking for dough balls (seldom an issue, but I try to maintain consistency in process). I then take my thermometer and take the temperature about 2/3 of the distance from center to edge and 2/3 of the distance from top of the mash to the bottom of the kettle. IME, this has been very repeatable and consistent for me.
 

wilserbrewer

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I would suggest only checking temp after a thorough stir, otherwise you’re likely just collecting a bunch of data points and will frustrate yourself.

The next question, “how long do I need to stir”

I have found that it takes a good bit more stirring than one would think to get a homogenous temperature throughout the mash.

It also takes longer than one would think for the temp to stabilize, that is the grain heating up, and the strike water transferring heat to the cold grain.

To that end my suggestion is to stir well upon mashing in, let the mash sit a few minutes, then stir again, then take your temp.

I have a hunch that if one mashes in quickly, and takes a temp, a false high reading will result because the temp has not stabilized and the cooler grain is still drawing heat out of the hotter strike water.

I suspect this is the case for some that report temp loss right away, that is they failed to let the mash stabilize prior to reading mash temp, and were misled.
 

C-Rider

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I might have to try that LONG stiring next brew. In the past I:
1-preheat the cooler w/the bag in place while I grind the grain.
2-add the grain one coffee cup at a time stirring as I add.
3-give the whole batch a good stir for a few min at most.
4-place a "spacer" just above the mash, stickin a temp probe and
close it up and cover w/a number of flannel shirts.
5-after 15 min stir again for a min and add some (sp) amylise
6-repeat #4.
7-stir again after 30 min
8-Stir again after 1 hr done and take brix reading.
9-Add to boil pot and get on w/it.
 

FloppyKnockers

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I'm not going to be a help in this reply, rather I have a question. When you say 'drop in the bag' do you mean you have all the grains in the bag and then put it in the strike water? Or rather put the bag in and then slowly pour in the grain while stirring?

Inquiring minds want to know.
 

C-Rider

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I'm not going to be a help in this reply, rather I have a question. When you say 'drop in the bag' do you mean you have all the grains in the bag and then put it in the strike water? Or rather put the bag in and then slowly pour in the grain while stirring?

Inquiring minds want to know.
1-preheat the cooler w/the bag in place while I grind the grain.
2-add the grain one coffee cup at a time stirring as I add.
 

wilserbrewer

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I'm not going to be a help in this reply, rather I have a question. When you say 'drop in the bag' do you mean you have all the grains in the bag and then put it in the strike water? Or rather put the bag in and then slowly pour in the grain while stirring?

Inquiring minds want to know.
As with most things homebrewing, opinions vary. People claim success with all 3 methods.

1. Add grain slowly to strike water a small amount at a time while stirring.

2. Dump all the grain into the strike water in one shot and stir.

3. Add grain to bag and add bag with grain to strike water.

Each method may have some advantages / disadvantages.
 
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