STC-1000 temp controller advice

Is it on cooling mode? If it's on heating mode it will cut in at the setpoint instead of cutting out and keep getting colder and colder.

 

Make sure you are plugged into the correct outlet. If your fridge/keezer is plugged into the heating side and set to 68℉ then it will keep running thinking that it istrying heat while getting colder.

 

Yep, I think your best best is to re-wire or just double check your wiring and make sure you are in the right outlet (assuming you are using an outlet).

Also, this is an obvious thing to say, but I have to say it. The STC-1000 is in Celcius, so you are going to want to set it to 20º on the digital read-out. I know this probably isn't the problem, but I have seen people make this mistake before.

 

One easy way to test is to hook the output (ie, the plug that will go to your freezer) to a lamp. If your ambient temp shows at, say, 75F, and you put your set temperature at something below that (like, say, 65F), and the light comes on, that means your controller is in heating mode. If it does not, it is in cooling mode. You want to be in cooling mode.

 

Wow. Those things are about thirty bucks less than my Rancos which were cheaper than Johnsons. Is there some tradeoff I'm missing?

 

There may be other differences, but the one thing I see is that the STC-1000's relay is rated at 10 amps, while the others are higher IIRC.

 

Explain to us non-engineers/electricians why that matters. Please?

 

An amp is a unit of electrical current. If the device being controlled (fridge or whatever) draws more current than the controller is rated for, it (the controller) may fail.

 

Not entirely true; it depends on your power source. The relays are rated at 10 amps @ 240 volts, but are also rated at 15 amps for 120 volts. The controller is available in either 120 volt or 240 volt flavors. I've got one and built it up - it seems to work well for me at this point, although I have not given it a very thorough work-out.

I fermented my last batch at 65F and seemed to hold the temp pretty well, +/- a degree or two. I may end up tweaking after I have more experieince with it.

If you're not afraid of wiring a small project and can read a schematic, it really is pretty easy.

Cheers!

 

For a couple of bucks, you can pick up an SSR on ebay that will allow you to switch as many amps as your little heart desires!

 

Not for the faint of heart.

Good to know. 15A is probably beefy enough for most homebrew fridges.

 

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Hmmm... The three freezers I bought recently all specify a 20A dedicated circuit. s'up wit dat?

 

Conservative overkill maybe. What's the actual specified current draw? I bet it's lower than 20A.

 

Not sure if this helps at all... but I built two controllers using the STC-1000's a year ago, one for my Sanyo mini-fridge kegerator (only used for cooling), and the other for my Magic Chef mini-fridge fermentation chamber (heating & cooling). They have done exactly what I wanted them to do, non-stop, for that year. Great, inexpensive and easy to build way to control temps.

We've had 14 responses to this thread, but have not heard back from the OP as to if anything above helped with his problems...

 

Google STC-1000 - definitely your friend on this one, plenty of manuals, diagrams, youtube videos, etc on wiring and best way to use it

 

I started to type this myself, then remembered I saw it on another site, so credit to whoever originally typed this programming info up:
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Press the "S" button to cycle through and select the setting you want to change. When you get to the setting you'd like to manipulate you can hold down the "S" button and the up or down key simultaneously to change that setting. When you reach your desired number release the two buttons and press the power button to save your change. If you don't press the power button within ten seconds your change will be lost and you'll have to start over. So make sure you save each setting after you set it, you can't set all four and save once.

F1 Temperature Set Value - This is your target, the temperature you'd like the controller to retain, it can range from -50C to 99C, it defaults at 10C

F2 Difference set value - This is how much wiggle room you'll allow before you want the controller to start heating or cooling your environment, it can range from .3C to 10C, it defaults at .5C

F3 Compressor delay - This is how much time you'll force the controller to delay in between cooling cycles to protect against it wearing out your refrigerator or freezer's compressor. If you turn a refrigerator off and on every 15 seconds you run the risk of killing it. This setting protects against that. The setting can range from 1-10 minutes, it defaults at 3 minutes

F4 Temperature Calibration Value - If you think the controller is wrong about the current temperature (presumably because you have another thermometer that you trust that's giving you a different reading) you can make corrections to the controller's measurements to calibrate it. Corrections can range from -10C to plus 10C, defaults at 0C

The default display is the current temperature that the probe is reading.
If the heat light is on it's heating the environment
If the cooling light is on it's cooling the environment
If the cooling light is blinking it's waiting out the compressor delay before cooling

 

and from me - make sure that the brass connector between the 2 plugs has been clipped - otherwise both plugs are operating at the same time, not independently