Beer Brewer’s Temperature Controller


Steady fermentation temperatures, usually at about 65 degrees Fahrenheit, are an important part of brewing beer. Because of this, the wort (unfermented beer) is often temperature controlled during fermentation. [android] needed a temperature controller for fermenting beer in a chest freezer. Much like the energy efficient fridge hack from last month, the chest freezer is switched on and off to achieve the desired temperature. Instead of buying a controller, [android] built around an existing design. His project uses a solid state relay to switch an outlet on and off.

The temperature is controlled by a home thermostat. He removed the thermistor from the unit and extended it with 24 gauge wire so that it can go inside of the chest freezer. Utilizing a junction box, the freezer is plugged into one switched outlet and controlled by the thermostat via the relay. The other outlet is unswitched and provides DC power for the relay using a wall wort transformer. Although this thermostat cannot be set cold enough for lagering, it is perfect for keeping kegs at the correct beer serving temperatures when not being used for fermentation.

12 thoughts on “Beer Brewer’s Temperature Controller

  1. Humm, there’s all kinds of things that will get in the way of this working. Off the shelf, the freezer probably has a timer to control the defrosting cycle. So cutting the power would essentially stop the timer making it hard to guarantee the freezer will go into a cooling cycle when ever powered up. Also, many (if not all) off the shelf house thermostats will include a back off timer so as not to cause undue stress on the cooling system. I think the average temperature will be obtainable. But I think the actual temperature will very depending on the randomness of some of these (now unwanted) features.

    Did anyone look deeply into the thread and see if these issues were considered?

  2. I looked far enough to see that the person doesn’t appear to be “electronically-inclined”. Mechanically, yes – he was able to describe how to use a soldering iron to melt the solder, etc… In fact, he mentions in the forum post that he copied someone else’s design, so he didn’t pioneer this (as we all knew already).

    Now don’t get me wrong – I’m not knocking the guy (assuming it *is* a guy – my apologies if not) in any way. We all started not knowing anything, so I commend anyone for making something do something it wasn’t originally designed to do. After all, isn’t that the basic definition of a “hack” anyway?

    I’m just sayin that I’ve come to hold Hack A Day to higher standards – especially with such recent somewhat-related posts as those Mike described in his write-up. Stuff like the kegerator kinda makes this look like childs-play, not someone old enough to drink beer.

  3. yeah, i’m not electronically inclined and like i said, it was a copy of someone else’s design, they figured out all the issues prior to making it and have said that it works just fine. i’m still working out a problem with the DC power plug i used for it, i don’t think it works and is why it was sitting in the basement. and i assure you i’m old enough to drink beer. our website is about sharing ideas and working through making trinkets to go with out obsession of beer making, i never intended this to be on hack a day.

  4. i see several problems with this.
    1. he didn’t use an arduino to pick up the temperature
    2. there aren’t any peltier plates
    3. no twitter feed on current alcohol percentage (which imo would be a good idea)

  5. With a bit of work (and luck) he could get the thermostat to operate in a range more appropriate to beermaking. With measurements of the thermistor’s resistance at two known temperatures, you can figure out how many ‘ohms per degree’ the particular device exhibits. If you’re lucky and it’s a PTC device, adding a series resistor of appropriate value (say whatever works out to ~20C) will make the thermostat register 20C hotter than normal. A well chosen value should give a more useful range I would think.

  6. Meh. Most basements hover around the correct temperature for Ales in the fall/winter/spring. A little cooler usually does not hurt it only prolongs the fermentation time. Only the first few days of fermentation are critical anyway. So even if you do not have a basement, just look at the weather report and if the next 3-4 days are in the 60s, then you can brew beer. Then the stick the brew off to the side for the next week or two before you bottle/rerack.

    Even lagers are pretty simple as a standard fridge is able to get it to the correct temperature, or if you live in a cooler climate, just keep it in a 4 seasons room or attached garage that gets enough heat to stay above freezing. If you start in november/december then it should be ready by spring.

  7. the project is complete, you can go to the website linked here to see the finished photos and explanation of what was going wrong for me.

    Bob, fermentation temperature control is one of the most important aspects of beer making. this device was built to help control lager fermentation, i’ve never had a fridge that will consistently hold 50 deg, they always waver too much and a few degrees on the first 48-72 hours of fermentation can ruin a lager. while i agree with you about ales, it really depends on where you live in the US. in the upper midwest and a few other places, basements will often be OK, but the thing we have to remember is that fermentation raises the temperature of the fermenter 4-8 degrees, so if you basement is 62, where you want to ferment, the active fermentation period could be as high as 70, which, in my book, is completely unacceptable.

  8. Just found this one: Brewer’s Edge Digital Beer Temperature Controller II .Best of all, no wiring is required. Just plug what you want to control in the outlet cord, put the submersible sensor in the area to be controlled, and program the temperature. (The sensor cord is only 1/16″ diameter, requiring only a small hole to be drilled or simply lay the sensor cord between the door seal and the main unit).

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