Keg MLT Strike Temp?

Hey guys, I recently switched over to a converted keg MLT. Before, using a cooler, my strike water needed to be at about 170 to stabilize the mash at 155. Last time, when I heated the water in the MLT to 170 and added the grains, the temp didn't even drop below 160. I know that the reason is because the MLT was already at the strike temp and not absorbing heat - I wasn't thinking!

So my question is, for those of you who use them, what water temp do you shoot for? I was going to just try 160 next time and add heat if it was too low, but I thought I would ask first. BTW - I like to mash thick at 1 qt/lb of grain. I'm sure that ratio has an effect on the temp, too.

Cheers!

You can pretty much follow the equations Palmer has here:

http://www.howtobrew.com/section3/chapter16-3.html

It varies according to the variable "r" or the ratio of water (qt) / grain (lb). I am assuming these calculations will hold for most vessels.

zoebisch01 said:

You can pretty much follow the equations Palmer has here:

http://www.howtobrew.com/section3/chapter16-3.html

It varies according to the variable "r" or the ratio of water (qt) / grain (lb). I am assuming these calculations will hold for most vessels.

Click to expand...

OK. Something's not working out right, though. If I've got water to grain ratio of 1, target temp of 153, and grain temp at 70, then I get:
Tw = (.2/1)(153-70) + 153 = 169.6

So, how did my mash end up at over 160 deg? I stirred for several minutes to make sure everything was mixed well. Is the metal in the MLT continuing to heat the mash?

I'd really like to hear from some of you guys that use a converted keg as a MLT. I know you're out there!

It depends on what temp I want to mash at. I heat the water in the tun to that temp, ad the grain (drop of about 6 deg), stir like hell, and then bring the temperature back up to the mash temp (150 for most of my ales).

Same thing with a step mash, I just start with the lowest mash temp and raise it as required... that's the beauty of the keg-as-mash-tun.

One thing I do find though, is that the thick metal ring that forms the bottom of the keg retains a great deal of heat that can then transfer into your mash around the edges... therefore, hot-spots happen. Solution- stir like hell, wait a little longer before I cover it, and this weekend I'm going to spray that ring with some water...

Hope this is helpful. -p

Doh, never mind. I didn't realize you heat the MLT. The thermal mass of the tun itself is the factor for sure, guess I missed that in your original post. I would follow what perry says.

You could actually make a 'fudge factor' to that equation (or rather a new equation) if you record the temp of the water, and then what temp it goes to after you add the grain. If you did this several times you could easily make an equation tailored to your tun. Of course, that would require experimenting.

This is more or less a shot in the dark but say you are off by 155/160 is .96875 try making the strike water 169.6*.96875 = 164 ish. See if that works. You could always go a little lower say 162, but be prepared to bring it up if it is low. This is shoddy and a shot in the dark, I know...but it should put you closer to the ballpark.

perry said:

It depends on what temp I want to mash at. I heat the water in the tun to that temp, ad the grain (drop of about 6 deg), stir like hell, and then bring the temperature back up to the mash temp (150 for most of my ales).

Same thing with a step mash, I just start with the lowest mash temp and raise it as required... that's the beauty of the keg-as-mash-tun.

One thing I do find though, is that the thick metal ring that forms the bottom of the keg retains a great deal of heat that can then transfer into your mash around the edges... therefore, hot-spots happen. Solution- stir like hell, wait a little longer before I cover it, and this weekend I'm going to spray that ring with some water...

Hope this is helpful. -p

Click to expand...

Thanks, perry. I could try that, but I think I'd rather get close to begin with. If you're saying ~ 6 deg drop, then maybe I'll go with the 160 I was thinking and see where that gets me. I'd be happy with 154 +/- a couple of degrees.

Also, my next batch will be my first 10 gallon batch. I'm guessing that it shouldn't really make any difference, though. Right?

Lil' Sparky said:

Thanks, perry. I could try that, but I think I'd rather get close to begin with. If you're saying ~ 6 deg drop, then maybe I'll go with the 160 I was thinking and see where that gets me. I'd be happy with 154 +/- a couple of degrees.

Also, my next batch will be my first 10 gallon batch. I'm guessing that it shouldn't really make any difference, though. Right?

Click to expand...

I am guessing it won't change it much. What is happening is your MLT is releasing it's stored heat into the cooler grain. This is why the equation is not working correctly. If you notice, there is no dependency on the amount of grain, so theoretically it should not matter if you do 5, 10, 50. (although with larger scale there are always other factors that come into play). If your keg is roughly the same design as perry's you can expect similar results. But if yours is much heavier, etc...then you will experience higher temperature increases.

sparky wrote:

"Also, my next batch will be my first 10 gallon batch. I'm guessing that it shouldn't really make any difference, though. Right?"

It doesn't seem to. I'm no scientist, but it seems to me that he important thing for temperature transfer is the ratio of water to grain. I find also that with the 10 gallon batch the residual heat in the tun has less of an effect on the overall mash. I'm still gonna spray the thing down, though.

-p