Interesting BIAB issue

[eulipion2]

I brewed a BIAB/No-Chill SMaSH IPA today for Big Brew, and during my mash my thermometer was pretty consistent at about 150-152, but once I started stirring to come up to mash-out temps, my temperature dropped dramatically into the 140s. Now, I know that when I'm heating up to mashing temps, if I don't stir I may end up with hotter water outside my grain bed than in, but I've never had my grain bed hold temperature while the liquid around it dropped.

Has anyone else experienced this?

 

[JuanMoore]

Now, I know that when I'm heating up to mashing temps, if I don't stir I may end up with hotter water outside my grain bed than in,....

This sentence confuses me. Are you saying you add the grains to cold water and then heat the whole grist to mash temps? You should be heating the water to strike temps and then mixing the grain in. Either way it sounds like you had some serious temperature stratification going on during your mash. Can you describe your process a little more?

 

[eulipion2]

Yes, I heat my grain and all my water together. When I was first reading up about BIAB a few years ago, this seemed like the most popular method, so it's what I started with, and I really like it.

That said, I think I'm just going to have to stir and adjust a few times during my mash to avoid stratification.

For my batch today, I'm wondering if different areas of the grain bed mashed at different temps throughout, and what that will do overall.

 

[etoews]

think i've got to be with juanmoore on this one. the water should be heated first then grains added. reason it's called a 'strike temp' is because it's not your mash temp; it should be a bit higher (maybe 5-10 degrees or so depending on your mash vessel) then grains added. your temp will drop... i do biab all the time and mash/boil in a keggle and with the proper numbers plugged in, beersmith tells me that this strike temp needs to be roughly 10 degrees higher than mash.

anyhow, hope this helps.

 

[eulipion2]

Total-water mashing has worked for me for three years, so I'm really in no rush to change. It's just that I was distracted by Big Brew today, so I didn't really stir my mash like I usually do. I was just wondering why my grain bed held temperature while the liquid around it cooled so much, or if anyone else ever had this issue.

I hit my mash temps, stirring until I got there to keep the temperature even inside and outside of the grain bag, so heating the grain with the water had nothing to do with it; it's when I let my mash sit that the liquid outside the grain bed, over the course of an hour, dropped dramatically. That's the issue. Thermometer read 152 for the whole hour until I stirred to come up to mash-out temps, at which point my temp dropped to the mid-140s.

 

[wyzazz]

Your grain bed has more mass/is more dense than the surrounding water, it should hold it's temp better than the water.

 

[eulipion2]

Your grain bed has more mass/is more dense than the surrounding water, it should hold it's temp better than the water.

Y'know, I guess I never thought of it, but if the grain bed is slower to heat up, it makes sense that it'd be slower to cool down. So obvious, but I've never noticed it.

 

[1fast4door]

I've only done 3 BIAB's. But two out of the three I've had inconsistent temps within the kettle. My problem is that I need to make a new bag as mine is too small and the grain doesn't spread out as well as it could. I think this causes the large, rather compact, grain ball to be like insulation. I had great success with my first try, having stove on low under the mash. Kept temps right at 153. This last time I did the same thing, only the water was around 153 but it was 168 in the center of the grain bed!