Mash stirring how deep?

[bd2xu]

I am using a direct fired recirculating mash tun that is a keggel. When doing a 10 gallon batch like right now, and I have about 26 pounds of grains in there, how deep should I stir the mash bed? I am making a lager and doing a step mash so when I heat the vessel and recirculate I also stir to get all of the temperature equal. Should I stir all the way down to the false bottom and get the entire mash bed mixed or just the top half? I thought I read somewhere once that you only need to stir the top half and let the bottom half be still but not sure?


On deck: Imperial Stout, Vienna Lager
Primary: Empty
Secondary: Mojave Red, Irish Stout, Tramp Stamp Clone, Helles, Oktoberfest, Roggenbier
On tap: Naked American Wheat, Turbo IIPA
Bottled: Dwarven Gold Ale, La Fin Du Mond clone, Hefeweizen

 

[m00ps]

I've always stirred all the way down because I worry about the whole mash becoming thermo-stratified. I do a single vessel BIAB so my mash tun is also my kettle heated from the bottom like yours. I notice large shifts in thermometer readings before/after I give it a good stir. But I have no actual data to back that up...

 

[jbaysurfer]

I've always stirred all the way down because I worry about the whole mash becoming thermo-stratified. But I have no actual data to back that up...

Are you batch sparging? I dough in, then recirc only when I need a temp bump and the burner is on or when I'm vorlaufing. I do a quick stir (to the bottom) right before vorlaufing. Drain tun, add water for new batch, vorlauf, drain tun, repeat based on how many batches (rinses) you're doing.

In short, after dough in, I only stir once, right before draining the tun and vorlaufing. That's enough to release any sugars stuck in crevices in the grain bed, and the rest is just rinsing them through to the brew kettle.

If you're recirculating while direct firing (and I highly recommend it, it's basically a RIMS system using the burner heat instead of a hot water heater element), the flow of the hot wort through the grainbed should distribute the heat just fine.

If you have a direct fire mashtun without a pump, you'll have to stir, and I'd stir all the way down because the bottom of the grain bed can get to 200 while the top isn't even at mash out temps yet.

 

[m00ps]

Are you batch sparging? I dough in, then recirc only when I need a temp bump and the burner is on or when I'm vorlaufing. I do a quick stir (to the bottom) right before vorlaufing. Drain tun, add water for new batch, vorlauf, drain tun, repeat based on how many batches (rinses) you're doing.

In short, after dough in, I only stir once, right before draining the tun and vorlaufing. That's enough to release any sugars stuck in crevices in the grain bed, and the rest is just rinsing them through to the brew kettle.

If you're recirculating while direct firing (and I highly recommend it, it's basically a RIMS system using the burner heat instead of a hot water heater element), the flow of the hot wort through the grainbed should distribute the heat just fine.

If you have a direct fire mashtun without a pump, you'll have to stir, and I'd stir all the way down because the bottom of the grain bed can get to 200 while the top isn't even at mash out temps yet.

Ive got the whole volume of water in there at once and just barely applying heat to keep it at the mash temp. Its kinda embarrassing, bu I actually dont know exactly what batch sparging is since I never went full-on traditional all-gran...

 

[jbaysurfer]

Ive got the whole volume of water in there at once and just barely applying heat to keep it at the mash temp. Its kinda embarrassing, bu I actually dont know exactly what batch sparging is since I never went full-on traditional all-gran...

Oversimplified answer: You take all your mash water, drain it, add all your sparge water, drain it.

If I was direct firing it like you are, I'd stir the whole thing, especially the bottom. You don't want to be aiming for a 150F mash temp on your thermometer only to have the thermal mass of the grain collect the heat from the burner and be at 180F on the bottom.

I'd also try to apply as little heat as possible for as little time as possible. This can be accomplished by hitting your mash in temp from the start and insulating your mash tun well. Wrap it in towels blankets, reflectix, foam, whatever you've got. Just (and this should be obvious) make sure to remove it before firing the burner again. You can probably hold your temps longer then you realize if you do this right, and run the burner less.

There's lots of ways to do this stuff, whatever works for you!

Edit, I just realized you're not the OP, so some of that might have been unsolicited advice...sorry 'bout that!

 

[m00ps]

No prob, yeah i've noticed at like a millimeter past the very lowest setting itll hold the mash temp for the whole mash period. But I still notice that it gets much cooler on the outside and the grains settle near the middle of the kettle so I stir it all up every 10 min or so and it goes right back to the mash temp

 

[bd2xu]

I'm fly sparging and i did stir the whole bed. I thought I read or heard to only stir the top 1/2 or 2/3 above the false bottom, but not sure why that would make sense...

 

[acidrain]

I never had any luck trying to hold temps in a direct fired kettle. In fact I scorched a few batches doing it.
But yeah, you want to get the heat as even as possible. Stir deep.

 

[bd2xu]

Turns out I scorched the **** out of this batch. 10 gallons of wonderful lager, almost done fermenting, and I taste a faint ashtray twang in the finish... CRAP. Doubt this will get better with lagering, probably worse, but i'll see if drinkable. I had the pump on pretty fast the whole time I was heating and using a 6" banjo burner to heat my keggle mash tun. have not had a scorching issue before, but this was a 10 gallon mash with steps at 100, 122, 146, 156 and 170.

 

[ABVIBUSRM]

get balls deep into that mash bro and mash it up

 

[jbaysurfer]

Turns out I scorched the **** out of this batch. 10 gallons of wonderful lager, almost done fermenting, and I taste a faint ashtray twang in the finish... CRAP. Doubt this will get better with lagering, probably worse, but i'll see if drinkable. I had the pump on pretty fast the whole time I was heating and using a 6" banjo burner to heat my keggle mash tun. have not had a scorching issue before, but this was a 10 gallon mash with steps at 100, 122, 146, 156 and 170.

That's a lot of steps. I do a 10 gallon mash on the small burner:

And try to keep the heat almost as low as it will go...or just above it. I keep the pump on at as high a rate as I think I can sustain without disturbing the grain bed too much and don't seem to have any scorching....

That said, that's a lot of steps and a lot can go wrong with a burner that big on a mash that size. I'm sure you can make it work...just have to keep that gas very low...and hopefully have a good needle valve.

 

[bd2xu]

I had the 6" banjo burner



On full bore for every step, pumped at about 75% and stirred a ton. I've gone full bore before but that's usually on just a mash out and this is only my second or third step mash. It takes a long time to raise the temp even w the flame high. But from now on going to lower the flame to abt 25%.



Primary: Maibock, Helles (first partigyle batch), Oatmeal Brown Ale
Secondary:
On tap: Orange Belgian IPA, Turbo IIPA, Mojave Red, Black Magic Stout
Bottled: Dwarven Gold Ale, La Fin Du Mond clone, Hefeweizen