Heat Loss From Mash Tun

[nickofosho]

Brewed my first all grain batch yesterday, which went pretty well, but my mass ended up about 4 degrees to cold to start. I heated the strike water, compensating for the temperature of the grains, but not the mash tun (10 gallon Rubbermaid cooler) itself. The grains and MLT were sitting next to each other for an hour before the mash, but apparently, the MLT was cooler than the grains. Plastic vs. grain I guess? Any suggestions on how to compensate?

 

[kh54s10]

Not sure exactly what the problem was. Did you preheat the tun. When 90% to mash temperature, I put a gallon or so in the tun while the water continues to heat. When it is ready I dump the water out of the tun add the heated mash water the add the grain. I am usually very close to the right temperature.

 

[logan_the_huge]

I heat up some water before the strike water just to heat up my mash tun. I use the same set up as you it sounds like. Heat up some water and add I mash tun, shake it up, seal it, then dump that water right before I start mashing.

 

[feinbera]

I just heat my strike water a couple degrees hotter than the calculator tells me to. I also make about a gallon of "extra" treated strike water, which I pull out and start heating on the stove while my burner brings the main batch of strike water up to temp – this extra gallon is usually up to a full, rolling boil by the time I mash in, in case the mash still comes up a degree or too cool and needs a little kick in the pants (don't add all of it in one go – just a quart should be enough to move you two or three degrees).

The calculators don't account for heating the inner walls of the tun itself, probably because people have such a diverse array vessels they mash in that, no matter how they tried to model it, they'd be wrong for more people than they'd be right for. Try pre-heating as per kh54s10 or logan, or overheating (but maybe not both), and take lots of measurements and care careful notes, you'll be hitting your strike temperatures on the head in no time.

 

[Homercidal]

Beersmith is supposed to calculate for preheating the tun or not. It is supposed to compensate for grain temp too. I'm almost always a bit low if I don't compensate.

What I do is add about 5 degrees to the temperature and if I hit high I can add ice cubes to bring it back down real quick. It's a LOT easier to cool a mash than it is to heat it up (for most people with a cooler mash tun anyway)

 

[ulnpiper]

When the strike water gets to about 150 - 155F, I take a gallon or so and use it to preheat my 10 Gal Igloo cooler MT.

In the 10 minutes to preheat the cooler, the strike water is usually up to the ~168F needed to mash.

I add enough water to the MT to get to the mash volume (usually another 3 to 3.5 gals.) swirling it around as I dump the water into the MT. Take the temp and adjust up or down as necessary before adding the grains.

I've found by taking my time at this stage, it makes a huge difference in hitting the mash temp.

 

[IslandLizard]

You can compensate for heat capacity of the mash tun, but none of the calculators add in the heat loss while stirring the mash with the tun open, steaming off your precious heat. For my 52qt "Extreme" cooler tun, 4-5 degrees is lost while mashing in a 12-14# grain bill at W/G ratio of 1.5. If I want to stir again after 10 minutes I lose another 2-3 degrees, if I work fast.

So.... I start 7-8 degrees higher than the calculator tells me (365 or BF), by the time I'm mashed in it's only 2-3 degrees high. I let it sit for 10 minutes and stir again, quickly. It's spot on after that. Close it up. I lose 1-2 degrees over the next hour without opening the tun or maybe once, lifting the lid half way after 30 minutes to double check the temp. I also have the grist covered with a double layer of heavy duty aluminum foil, and poke my thermometer through that to measure.

 

[nickofosho]

Great info! I think I'll just preheat my MLT with some hot water next time. Don't know why I didn't think of that. I do it with my coffee mug every morning to keep my coffee hot longer! Thanks!!

 

[troglodytes]

You can compensate for heat capacity of the mash tun, but none of the calculators add in the heat loss while stirring the mash with the tun open, steaming off your precious heat. For my 52qt "Extreme" cooler tun, 4-5 degrees is lost while mashing in a 12-14# grain bill at W/G ratio of 1.5. If I want to stir again after 10 minutes I lose another 2-3 degrees, if I work fast.

So.... I start 7-8 degrees higher than the calculator tells me (365 or BF), by the time I'm mashed in it's only 2-3 degrees high. I let it sit for 10 minutes and stir again, quickly. It's spot on after that. Close it up. I lose 1-2 degrees over the next hour without opening the tun or maybe once, lifting the lid half way after 30 minutes to double check the temp. I also have the grist covered with a double layer of heavy duty aluminum foil, and poke my thermometer through that to measure.

I'm going with this method from here on out. I have been so focused on the beersmith numbers recently that I end up missing my mash temp by 2 degrees on the low side everytime because of stirring while mashing in. I wouldn't care all that much but in brewing saisons and mashing at 147 instead of 149 I feel like I'm really at the low range of acceptable temps.

My solution last night was a steady stream of infusions and a 90 minute mash to bring it from 147 to 148.5 to 150. Fingers crossed that the WY3711 leaves me with some beer and does just devour everything leaving me with alcoholic water.

 

[IslandLizard]

I'm going with this method from here on out. I have been so focused on the beersmith numbers recently that I end up missing my mash temp by 2 degrees on the low side everytime because of stirring while mashing in. I wouldn't care all that much but in brewing saisons and mashing at 147 instead of 149 I feel like I'm really at the low range of acceptable temps.

My solution last night was a steady stream of infusions and a 90 minute mash to bring it from 147 to 148.5 to 150. Fingers crossed that the WY3711 leaves me with some beer and does just devour everything leaving me with alcoholic water.

That's a good idea. Trying to raise the mash temp without a RIMS or HERMS is like chasing your own tail. Each time you re-infuse with a gallon you're almost back to where you started, 'cause of the open tun and stirring. After a few brews you'll know exactly where the right strike temp lies.

Don't worry, 3711 will leave a nice dry beer. It can't eat everything.