Temperature control

[Editor's note: this is a 'conceptual post', and should be read in the voice of a charismatic American Southern Baptist Preacher. If you don't know what that sounds like, please have a friend read this post to you. Thank you. /Ed.]


One of the keeeys to making good homebrew is temperature control. That's because the yeast-- who really are in charge of turning the wort that brewers brew into beer that people drink-- are very finnicky creatures by our human standards. A two-degree change in temperature for them is like a 100-degree change for us...more than that. You change the temperature by only a couple of degrees, and they start putting out entirely different chemical compounds. And by that I mean, stuff that changes the flavor of your beer. [cue: 'Yeast Gone Wild' by Waylon Jennings]

U lose hombre, you LOSE!

If you have no control over your fermentation temperature, suffice to say, you have no control over the beer your trying to make, no matter how the brew day went. Your beer will S.U.C.K.
[cue: sad banjo tune]

And the opposite is also true! If you can maintain your fermentation temperature within a degree or two, especially during the critical first stage, your beer will be much better. To that end I've tried over the last few years, different ways to maintain constant temperatures during fermentation.


I won't go into that here. You can ask your local vicar, parish priest or pastor to enlighten you on the finer details.  I just wanted to post a couple of pictures of a little project that I did today, wiring up a dual temperature control unit, to make some better liquor.


Here's the before:

Notice the absence of proper tools for dealing with electronics

That tupperware box towards the left cost 100 yen (76 cents US). I mounted the control unit inside it. I had some help figuring out how to wire it up to the heating and cooling outputs via the Internet on my trusty computer there, good old "Trusty". But the little things really chapped my ass-- stripping the wires without also severing them, getting them the correct lengths so everything would fit in the box, coupling and taping, my god! Headaches-ville. But it finally all came together and I tested it out, so:

My. Brain. Is. Bigger. Than. Yours.

Initially I set it up so that the 'heating' would kick on when it dropped to 15C. Here you can see I put the thermistor into some ice water to speed things up. The 'heating' output is actually plugged into a lamp that's off camera, lighting this shot. That means the light is on, because the temperature is below 15C, and the heating output is trying to warm it back up to 15 (by charging the lamp! Dumb-ass heating thingy!)

You'll phone home when I SAY you'll phone home, okay?

Now the thermistor is out, the lamp has shut off (that round crushed glass thing there on the upper right), and the cooling has switched on, evidenced by the other lamp that I have plugged into the 'cooling' output, which is lighting this shot. This is not a flash photo. Probably.

So that went pretty well, and at the moment I've got her hooked up to the ferm chamber like so:

Soylent green is People! Soylent green is People!

Hard to know what's going on here maybe, but that black cord goes to the thermistor, which is submerged in a vial of water taped to the inside corner of the ferm chamber. Right now she reads 17-point-something Celsius. That's because you can also set a buffer zone of between 0 and 10 degrees between when the fridge will kick on and when the heating will kick on. This preserves the compressor in your fridge. Right now it's still pretty warm out, so I don't have any heater plugged in (though I'll probably plug in a hair dryer once winter gets here).

I also noticed another thing while doing this. I've always trusted that the temp in the chamber is the temp of my fermenter, given a day or so to equalize. But today I realized that this was not so. I took a little hand mirror, a Calvin Klein job that my wife uses, and stuck it down next to the thermo strip on the bottom of the fermenter. Lo and behold. Two degrees warmer. My 18C 'on the dry side' beer was gonna be a 20C 'a tad sweet' one after all. Shizzle-me-frizzle(TM).

Homebrewer newbies, this is well known and well documented, but I never gave it much thought, preferring instead to secure the temperature integrity of my ferm chamber. A fermenting wort will itself generate heat, and you'd best be aware of that. You may like me, be lost in pride over your achievement in building a fine-ass fermentation chamber, and then a fine-ass way to control the temperatures therein.

But without being aware of the ACTUAL temperature of your beer, my homebrewing friends, you are truly LOST, do you hear me, LOST!!! Like that show on ABC a few years ago, that went on forever, and got you sucked into caring about the characters, even though they were all shits, and who or what the black smoke was, and why didn't Jacob's brother have a name, and what actually happened to Locke and whatnot, and why Walt wasn't in the final episode, and why...why...WHY!?!?

I dunno, dude. Could I have that baby?

Long and short: know your ferm temp and keep it consistent.