2 quick BIAB questions:

I just finished my second BIAB last night. It definitely went a lot smoother than the first and I'm on my way to getting the procedure down so it doesn't take me forever. But I'm concerned about the temperatures. I have a Taylor probe thermometer and it gives me way different readings depending on where I put the probe. I stir well every 20 minutes or so, or when adding direct heat. But no matter what, there is a huge variance in temperatures from the top to the bottom, sides to middle, areas with lots of grain and areas with lots of water, etc. This is in a 24 qt stockpot, 15 qts water and just under 6 lbs grain. What temperature am I looking for?

Relatedly, I'm using this 24 qt BK (Bayou) with the steamer insert to hold the bag. The thing is, adding 1 gallon doesn't even come up through the steamer; it's all underneath. This being more than 1/4 of my total mash water, I'm wondering if this has anything to do with temperature variation? Even though my water/grist ratio seems OK (AFAIK), the grains seemed a touch constrained, maybe because 1 gallon of the mash was not available for them to spread out in to. I like the ease of the steamer insert but I'm beginning to think I might be better served by going without it and using the tiny aluminum steamer I have to keep the bag off the bottom.

Can I get some thoughts from some BIABers (or not)? BTW, as far as I can tell my efficiency is fine (volumes are not exact yet), I'm mainly wondering about temperatures.

1. What temperature am I looking for?

If you are asking what your mash temp should be in general - Your mash temp depends on your recipe or beer style. If you are asking which reading is accurate (middle, areas with lots of grain and areas with lots of water, etc.), then I will tell you what I do.

I use one of those long-probe standard thermometers you see in the LHBS or in the equipment kits. During the mash step of the BIAB, I just give the grains and water a good stirring, then stick the thermometer right down in the middle of the kettle as low as it can go. I figure that's the best temp I'm going to be able to record.

2. Steam basket impacting temperature variation. The only thing I would worry about regarding the steamer basket is this:

a. Does it affect my strike water temp? Adding the bag of grains to the strike water will lower your water temp, but will the basket lower it even further? If so, you would need to start with a higher strike water temp to compensate.

b. How does it impact the volume of mash in the kettle? In other words, will it limit how much water I can put in for the mash without overflowing. Critical when dealing with smaller BIAB kettles.

3. the grains seemed a touch constrained, maybe because 1 gallon of the mash was not available for them to spread out in to.

I don't think your grains are restricted or restrained during the conversion process, as long as you are giving them a good stir at least two or three times during the mash cycle.

I highly recommend measuring your efficiency on every batch and recording it in a note book so you can dial in your technique. Also, it will give you confidence that your efforts are going well. This is helping me tremendously. I'm also recording boil off rate and grain absorption rate on every brew day to ensure I have a good average number to use for prepping future brew days.

OK I realize I probably should have been more clear:

I want to know where in the kettle the most accurate reading would come from. Putting it as low as possible in the middle sounds solid. Want to see if that's the consensus.

For the steamer basket, I have two concerns:

1) Since the grains are sitting on top of a good portion of my mash water, they are more constrained than they would otherwise be, and I feel like it makes temp monitoring harder because in some parts, my probe is covered with and surrounded by grain and in other parts it's mostly water.
2) I wonder about whether the heat is being distributed correctly or whether the SS steamer is creating a sort of stratified mash where the bottom, liquid portion heats up too hot and the top, grain-heavy portion heats unevenly/more slowly.

I think with a good stir, you wouldn't have that problem, but to be sure, you could just grab the bag and pull it up and down in the kettle. That should stir the water up enough on the outsides of the basket to get an accurate temp read in the middle. But, just guessing, really. Try it on your next brew session and see how it affects temp readings on the outside of the basket.

I've noticed this as well. With 5 gal 158*f strike water and 10 pounds of grain the mash should start at 152*f. In reality I am able to measure temperatures from 143-157*f. I stir very thoroughly. If I remove the grain bag the liquid temperature is usually closer to target so I assume conversion is occurring just fine. That and the fact that I generally get excellent attenuation. The actual grain solids take longer to heat.

Also at the end of the mash the temp should be consistent thoughout.