new mash tun - adjust strike water temp?

Just made myself a mash tun out of a 2 gallon water cooler (used these directions almost to a T) for my partial mashes. Up to this point I've mashed in an aluminum stock pot and strained the mash through a colander (thus the new tun). I use BeerSmith to calculate my strike water and, for the most part, it has been spot on.

How should moving from an aluminum to a plastic tun affect the temperature of my strike water? Since plastic is not as good a heat conductor as aluminum (right?), I should need to heat the strike water less (right?) because less heat would be lost to the mash tun (right?). My materials science isn't what it used to be.

Awhile back I started heating my strike water ~ 10F over my desired strike temp, then pouring it into my tun, letting it sit a couple minutes, then stirring it til it hits my desired strike temp.

Then I stir in the grain.

This effectively eliminates the need for pre heating your tun and saves water to boot.

I haven't missed a strike temp since I started doing this.

RCCOLA said:

Awhile back I started heating my strike water ~ 10F over my desired strike temp, then pouring it into my tun, letting it sit a couple minutes, then stirring it til it hits my desired strike temp.

Then I stir in the grain.

This effectively eliminates the need for pre heating your tun and saves water to boot.

I haven't missed a strike temp since I started doing this.

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Thanks for the suggestion. A couple of questions:

1) How do you calculate your desired strike temp? I've always used BeerSmith, which takes heat loss to the tun into account.

2) I thought I read somewhere that you should pour the water onto the grain, and not the other way around like you do. Never really thought about a reason why though - any issues with doing it this way?

1. I started out adding my grain to 170F strike water for a few batches and have just adjusted my strike water temp a few degrees up or down to hit my desired strike temp.

2. No issues at all. I usually have the wife pour in the grain as I'm stirring so I don't get doughballs.

The thing I like most about this way is that I heat strike water in 2 pots on my stovetop and getting both to the perfect temp at once, and then transferring to the tun w/o heat loss was nearly impossible. Now it's no issue and b/c I'm not using my burner for the mash, I save a ton on propane.

JLem said:

2) I thought I read somewhere that you should pour the water onto the grain, and not the other way around like you do. Never really thought about a reason why though - any issues with doing it this way?

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You have a higher incidence of dough balls if you pour your infusion onto the grain. This I have done. This I have regretted.

Mr. Mojo Rising said:

You have a higher incidence of dough balls if you pour your infusion onto the grain. This I have done. This I have regretted.

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So, did I have it backwards? It is bettter to pour the grain into the water?

Yes. It is better to slowly pour the grain into the strike water and have someone stir the mix in while doing this.

JLem:

You can set Beersmith up to ignore equipment adjustments for strike water by deselecting the "Adjust Temp for Equipment" check box in the Mash Profile screen. Then, Beersmith ignores equipment heat losses and only considers the grain.

Like lots of others, I add my water at 10 degrees or so over my calculated dough-in water temperature, then let it cool to the right temperature, and add my grains a little at a time. Works just fine.

Thanks all for the advice. The idea of heating above the desired dough-in and letting it cool down makes a ton of sense. I forgot too about that little check box on BeerSmith. I'm set to brew tomorrow - I can't wait to try my new mini-MLT!

just wanted to update: I brewed this past weekend using the new mash tun - it worked awesome. I missed my mash temp by a a degree or two, but that was because I failed to get everything ready before hand - I had to struggle with opening the grain bag and scooping it into the tun. Previously I just opened and dumped it all into my stock put tun, but I needed to be more careful with this. Next time I'll be ready and I'm sure I'll hit the temp on the nose. (For this brew though, a lower mash temp was probably a good thing anyways).

I wrapped the tun in a heavy blanket. I think the top is prone to heat loss. I only lost a degree or two over the course of the hour mash. I noticed too that at the end of the brew day, when I was cleaning up, the wort left behind in the mash tun was still quite warm - I didn't actually measure it, but I am impressed with the insulating capacity of this little thing.

Thanks all for the advice!