Temp Controller Round Up!

Temperature Controllers, sometimes referred to as overriding thermostats, can control devices like refrigerators, freezers and fermentation heating devices to provide a consistent temperature for your kegerator, fermentation chamber and mash system.  They do this by monitoring the temperature and cycling on and off the device in question.  Generally, you will set the device to full cooling or heating power and the temperature controller takes over from there.

First, some concepts…

Digital controllers have a digital readout and generally much more control.  Analog controllers typically have a preset differential that cannot be changed. Analog controllers are fine for your kegerator but, in my opinion, are not accurate enough for fermentation control.


Unwired means.. you have to hook up the electrical wiring.  It does not come with a plug in cord.  Not a big deal for most people.  Wired means… no AC wiring is necessary, the controller comes with cords that you can plug your cooling or heating source into.

Single/Dual Stage

A single stage has the ability to control either a heating or a cooling device.  A dual stage has the ability to control both a heating and a cooling device.  A note of clarification, just because a dual stage controller can control two devices doesn’t mean it has to control two devices.  Sometimes it makes sense to buy a dual stage controller even if you’re not going to use both stages right away.  The Control Products devices are what come to mind here.  Generally, the dual stage unit is less expensive or the same price as the single stage unit.  It makes sense just to buy the dual stage version.

PID Temperature Controllers
PID Temperature Controllers can be used in conjunction with a relay and a thermocouple to control your kegerator and fermentation temps.  You can also integrate a PID controller into your brew system to control mash temps.  There are many models of PID controllers and prices change frequently.  Check out the PID controllers tag for specific models.  Amazon (here) and Ebay (here) are good sources for controllers, relays and thermocouples.

Now, on to the controllers…

Single Stage, Wired

Johnson A419 Digital Temp Controller
Digital, Wired, Single Stage.

Ranco Wired
Digital, Wired, Single Stage. 

Ranco vs Johnson
Comparing the Ranco single stage controllers to the Johnson A419 line of controllers – Both controllers have the capability to run either a warming device or a cooling device.  One difference… With a Ranco controller, you’re able to make this switch using the menu interface.  With the Johnson A419 controllers, you have to open the case and change a jumper.  Most people will not be making this change often, if at all, so it shouldn’t be a big deal, but the difference is worth mentioning.

Johnson Analog Temp Controller

Analog, Wired, Single Stage.  Add a 5 cent filler item and this ships for free.

Single Stage, Unwired
Johnson A419 Digital Temp Controller
Digital, Unwired, Single Stage.

Control Products TC-9102S-HV

Digital, Unwired, Single Stage.

Ranco ETC-111000 Digital Temp Controller
Digital, Unwired, Single Stage.

Dual Stage, Wired
Ranco Digital Two Stage
Digital, Wired, Dual Stage

Graham Box Control Unit
Digital, Wired, Dual Stage.  This is a take off on the two stage Ranco.  It adds a logic unit and sensors that allow you to control Mash and Sparge temperatures.

Dual Stage, Unwired

Control Products TC9102D-HV
Digital, Unwired, Dual Stage.


Digital, Unwired, Dual Stage

Elitech 110V All-Purpose Temperature Controller STC-1000

Digital, Unwired, Dual Stage.  This is a very popular (and economical) DIY temp controller.  Many people source this controller from Ebay (recommended search here).  If you decide to go that direction, pay special attention to the power supply voltage.  Many of these are 220v models.  Most of you will want a 110v model as I link to here.


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5 thoughts on “Temp Controller Round Up!

  1. EchoTony

    I’m using a Johnson Analog controller. Works great for my freezer/controlled fermentation box. I’ve got a seperate heater contoller that is designed for warming mats for gardening. Both are plug in, and work well (although the heat controller doesn’t go below 68 degrees F).
    One day I’ll get a nice dual stage setup.

  2. KnowItAll

    PID control is incompatible with the compressor based systems found in virtually all residential (and commercial)freezers and fridges. If a PID controller has an on/off mode it can be used, but it will work just like the other controllers- no PID control benefits are gained.

    The Ranco controllers commonly used for homebrewing (and listed above) DO NOT have a “compressor delay” feature to prevent “short cycling”. This should be considered a mandatory feature, since without it you can kill your compressor in a matter of hours given the right conditions. The digital Johnson, Control Products, and even the cheap STC-1000 have this feature. Why Ranco does not include this feature is puzzling.

  3. Chris Banker

    I have a few of the Control Products dual-stage controllers and have been very happy with them.

  4. John

    The Ranco is great – easy to program and very consistent. Mine has performed like a champ for years now. I just ordered a second for winemaking. Check out HVAC Parts Warehouse, $47 + free shipping: .

  5. Tim

    Ranco controller rocks. You can pick it up on ebay for less than 50 and it works just as well as the johnson and costs far less.


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