Temps tire difference

[Nomofett]

Hi.
I do BIAB 8 liter batches.
In my mash I noticed that if I put my thermometer in the grain it is quite a bit lower than if I pull my bag out and check the water temp. or pull the bag to the side. If it was just a few degrees I'd understand but it can be 10 degrees Celsius off, which reading do I trust? I think the one in the grain because that's where the grain is, but if the water is a lot hotter then shouldn't that be important since that's hitting at least the outer layer of grain before it gets cooled?

Thanks!

 

[Nomofett]

Anyone? No one knows what I should do?

 

[slym2none]

I measure my temps with the grain in the water, 5-6 minutes after doughing in, and then I still give it a good stir before taking its temp. You should always give the mash at least 5 minutes before taking its temp, to give the temps time to equalize & stabilize. And stir it again, too.

 

[Nomofett]

Thanks. But yeah I do that as well, but my problem is that even 30 minutes in there is a huge difference between the temp if I put the thermometer in the grains or if I pull the bag over or up and measure the water temp.

So for example; I raise the water temp to 70, then I put the grain in. I wait a few minutes and measure and the temp with the grain is 65, but if I move the bag over and measure just the water it's still about 70.

Last Brewdog at the end I turedn the heat back on but the grain temp didn't seem to rise. I kept checking it but it only went up to 70. After about 5 minutes I got curious and pulled the bag out. With the grain it was still at 70, but when I pulled the bag out the water was at 80'

I'm very confused

 

[slym2none]

That... shouldn't be possible.

You just broke the laws of physics.

Someone, call Neil DeGrasse Tyson!

 

[Nomofett]

Hence my confusion.

Is it possible there's just so much water at the bottom that's not being cooked by the grains that that's throwing it off?

Here's photos taken 20 seconds apart from each other

View attachment ImageUploadedByHome Brew1456461871.462442.jpg View attachment ImageUploadedByHome Brew1456461907.934657.jpg

The difference is bigger than I remember

 

[tagillis]

I've experienced this while doing BIAB before. I think my grist was too tight. I was using a 16L rectangular cooler that was too wide to stretch my bag over the edges. I had to stir several times over the course of 10 minutes to get everything uniform and happy.

 

[slym2none]

I'm perplexed, unless your bag is smaller than your pot, and there is space where there is just water & no grain.

Still, I'd think that stirring & waiting would even that out.

 

[Nomofett]

Yeah, my bag is smaller than my pot. I always heard that it should be so it doesn't touch the bottom and get scorched.

 

[Nomofett]

Tag: even when I stir a lot it's still not uniform. Maybe I just need a bigger bag. Maybe I'll let it touch the bottom but just be careful not to let it touch when any heat is on it

 

[slym2none]

You are turning on the flame while the bag is in the pot?

I was taught to bring the water up to strike temps (higher than your mash temp so the cooler grains bring it down to mash temps), turn off the heat, put in the bag, then dough-in. I never have the heat on while the bag is in the pot.

This is the strike water temp calculator I use, but there are others out there. I have never been off by more than 1 degree using it.

http://www.brewblogger.net/?page=tools&section=strike

*EDIT*Yeah, get a bag that fits your pot better. A smaller bag than the pot might cause efficiency issues. You need the room to stir & for the water to flow freely!

 

[Nomofett]

Yeah, same. But I apply heat if it drops too low during the mash and I apply at the end for the mash out.

 

[slym2none]

You need to find a good insulator for your pot. I had a spare mattress-pad in the closet that I wrapped around my pot & only lost 4 degrees F over 80 minutes (153F to 149 F). Trying to get the temperature just right when you have turn the heat off & on is a huge pain.

Mashing-out really isn't necessary for BIAB. I just pick up the bag & let it drain, and turn on the flame for the wort in the pot while it's draining and/or I am squeezing.

 

[Nomofett]

It's not that I'm losing heat, usually it stays correct. It's just the difference.

I heard that thefts e out is good to release the sugars or make a sort of slide to go down them. I don't know, I just know I got better efficiency doing that. Squeezing makes me nervous cause of tannins and whatnot and I gotta wait so long forint to cool down.

I think I'll just get a bigger bag and see how that works.

Thanks!

 

[slym2none]

Squeezing will NOT release tannins. To do that you need temps higher than 160° F plus a pH that's high as well. Two things. Not one.

I offered the suggestion of insulating the bag due to you feeling the need to turn the burner on while you are mashing. If you feel the need to turn the burner on, you are losing heat, no?

Please, do get a bigger bag & let us know how that works out!

 

[McKnuckle]

You probably DO need a bigger bag. The best fit is when it's a second skin for the tun, separated from the vessel's containment area only when lifted out. Why? Because that limits or even eliminates having water floating around the grains, and solves most of the temp consistency issues. Or... at least it makes BIAB more or less equivalent to a traditional mash in that respect. Ideally, there should be no liquid outside the bag.

For direct heating, if you use gas, you probably can get away with applying it gently and not harming the bag. You can stir and get things moving while doing so if it makes you feel better. Insulating the tun is a major improvement in the whole process.

 

[Nomofett]

Awesome, thanks for all the help guys! I'll brew this weekend with a bigger bag.

 

[tagillis]

Tag: even when I stir a lot it's still not uniform. Maybe I just need a bigger bag. Maybe I'll let it touch the bottom but just be careful not to let it touch when any heat is on it

A larger bag would probably my first change. What size bag are you using?

Picking the bag up a few inches when you have to reapply heat for a minute or two should work. I've seen lots of people use that method.

As a test you could try mashing in the same bag but with a smaller amount of grain. I'm curious if you have the same temp differential. If you do then I'm just as baffled as you.

 

[Nomofett]

I'm not sure the size of the bag, it's just a laundry bag. I'm gonna pick up a bigger one tomorrow