Mash Tun Coefficient

I've made lots of brewing mistakes lately. One of the biggest was thinking I had nailed the thermal coefficient of my mash tun. I did an experiment to determine this awhile ago and I believe it came out wrong because my dial thermometer was messed up.

If you use a dial thermometer, check it at boiling and make sure that water boils at 212F. If you use a glass thermometer, ensure that you are submerging it properly. It should be marked for the proper submerging depth.

If your not familiar, to calculate the final temperature of a system from the starting temperatures, you multiply the mass of each part times it's temperature and specific heat, add them all up, and divide by the total mass.

So when I say tun coefficient what I really mean is finding the equivalent amount of water that the tun is equivalent to. So in Excel:

Tun = 0.5
Tun Temp = 72F
Water = 2 Gallons
Water Temp = 160F

Final Temperature =((0.5*72F)+(2.0*160F))/(0.5*2)

As long as you reference your cells right, you will be able to modify the tun value until the final temperature you calculate equals what you measure experimentally.

I found a value of 0.26 for my tun, meaning it's thermal mass is equal to 0.26 gallons of water. I fully calculate my mash temps in Excel, and use 0.051 for my equivalent thermal mass of one pound of malt.

Prior to solving this problem I was thinking about building a RIMS mash tun. No need now! I can mash in and hit my temperature as closely as I am able to measure the temperature of my strike water.

Don't forget to check the accuracy of your thermometers!

Whirlpool Oaking Expirement

I have been no-chill brewing lately. And I'm interested in doing a primary fermentation on oak, like a Firestone Walked Double Barrel Ale clone. So tonight I conducted a brief expirement to see if adding an oak cube to 2oz of boiling water and allowing it to cool would create any undesireable flavors.

The sample tasted woody, with vanilla and Lincoln Log. (if you ever bit a Lincoln Log when you were a kid you know exactly what I mean). Overall, I didn't taste anything bad so now I'm going to try it out in a batch of beer.

Making a 2 Degree Per Hour Mash Tun

My mashes are all over the place. I have been mashing in a 10 gallon rectangular cooler that I added a simple manifold to. I recently did a test that showed a 10 degree drop in temperature over 60 min. This is way too high, since I don't want to add hot water to adjust part way through.

I noticed when I did this test that the tun lid got quite warm. Upon further investigation, the lid is totally un-insulated.

My first inclination was to get some styrofoam, cut it to fit the inside of the lid, and then line it with plastic. Instead I used "Great Stuff", cut it down with a hand saw after it dried for weeks, and tried to seal some foil over the top with silicone.

This setup lowers my temperature drop to 2 degrees per hour, which amazes me and it's just what I want. However, don't do what I did. Just get a thick sheet of styrofoam and use 2 sided tape to attach it to the inside of the lid. Then cover that with heavy duty foil and possibly some more waterproof 2 sided urethane tape to hold it on.

I used white silicone that did not dry correctly, then covered it with packing tape. It's a hack job. Also, Great Stuff fumes a lot as it cures. So don't copy (exactly) what I did.