How to hard-wire the STC-1000

I just converted a fridge into a curing chamber for meat and cheese, and I used an STC-1000, which saved me about $50 off the conventional plug-and-play kegerator conversion thermostats. However, I used the direct-wire method, rather than wiring up a whole bunch of outlets, to save on cost and time.

I'm sharing this wiring diagram, because most of the wiring diagrams I've seen for the STC-1000 utilize outlets (an extra element of confusion for a beginner), and including the heating element, which really isn't needed for a kegerator or fermentation chamber setup. I'm also including programming instructions, because the instructions that ship with the unit are unintelligible.

Please note that if you decide to do this type of wiring, you do so at your own risk. You need to obey all local electrical codes.

You will need to buy or re-purpose a power cord to power the unit. The cord needs to be able to handle enough current to power the fridge, so don’t use a lamp cord! If you use a grounded power cord, you can connect the fridge’s green or bare copper grounding wire to the green or bare copper grounding wire of the power cord, effectively grounding the fridge, which is an absolute requirement. If your fridge cord is long enough, you can simply patch the STC-1000 right into the run of the cord. (You will still need some extra pieces of insulated wire to complete the wiring.)

First off, cut the plug off the refrigerator’s power cord and strip off the insulation from the hot, neutral, and ground wires.

Some basic electrical knowledge here for those of you who are unfamiliar. A typical power cord contains a hot wire that carries the current to the device…a neutral wire that returns the current to the outlet, thus completing the circuit…and a ground wire that carries away dangerous electricity if there is a wiring failure inside the device, so that you don’t get shocked when you touch it.

The hot wire is always black. The neutral wire is usually white…but if there’s no white wire, the neutral wire will be indicated by writing, markings, or ribbing along the cord’s insulation, so look or feel closely to determine which wire is the neutral wire. The ground wire is either bare copper or green.




So the hot wire from your power cord needs to be spliced to two other short bits of black wire (called “pigtails”) that run to slots 1 and 7 on the STC-1000 unit. Tape these wires together around the insulated part with electrical tape, and connect them securely with a properly-sized wire nut. The neutral wire from your power cord (white, ribbed, or writing/markings on the insulation) needs to be spliced to a pigtail that runs to slot 2, and to the neutral wire on the fridge’s power cord. The hot wire on the fridge power cord needs to run to slot 8 on the unit. (The neutral wire on the fridge power cord has already been connected to the neutral wire from the main power cord, along with a pigtail to slot 2.) Connect the ground wire from the fridge cord to the ground wire of the power cord with a wire nut, and now the fridge is grounded.

Plug in the STC-1000 to power it up. Press and hold the S key for 3 seconds to enter the setting mode. The first item that displays is F1, which is the temperature setting. The unit is in Celsius, so you’ll have to do a quick conversion. (Google does this for you if you type in this format: "65F in C") To set the temp, press and hold the S key while pressing the up or down arrow until you reach the temperature that you want your chamber to remain. Then press the power button once quickly to save the setting. (The setting will remain even if your power goes out…it only resets to the default setting if you manually reset the device.) The other settings don’t need to be modified unless you have problems later. (F2 is the “Difference value” which tells the fridge when to turn on after the temperature rises a specific number of degrees above your setting. The default setting is half a degree Celsius, which is fine as it is for most applications. F3 is the “Compressor delay time” which gives the fridge’s compressor a result, because you don’t want it cycling on and off every 30 seconds. The default setting is 3 minutes, which is fine. F4 is the “Temperature calibration value” which is used if you discover your device isn’t accurate and you need to adjust it. To switch between these values in the setting mode, press the S key multiple times until you arrive at the feature you need to change. If, at any time during the setting process, you don’t press a key for 10 seconds, the device forgets what you’ve done and returns to its operation mode. Don’t forget to press the power button once quickly to save your settings.)

Make sure to attach the temperature probe to slots 3 and 4 on the unit. Then run the sensor probe into your fridge and make sure it’s not touching the walls, the racks, anything solid. Now the STC-1000 unit will keep your fridge in whatever temperature range you need for the application!

Industrial strength velcro is a great way to attach the STC-1000 to the side of your fridge to keep it out of the way.

Please note that the first time you power up and program your STC-1000, it may take it several minutes to begin the first cooling cycle, so don't freak out if the fridge doesn't come on immediately. It needs a few minutes!

 

Oh my god this is brilliant. While waiting for my STC to arrive I've been looking around for wiring diagrams for cooling only (I live in Australia). My STC arrived in the mail yesterday so the timing could not have been more perfect. Thanks a bazillion.

(FYI, noticed a minor typo: "gives the fridge’s compressor a result". I think you mean "rest"?)

 

Awesome! So this way it is still wired through the freezers original thermostat. If the freezers original thermostat has a problem do you think just bypassing the wires of said thermostat would work? Thanks for the diagram!

 

Tag

 

What you could do is open up where the compressor is located. Jump a hot and nuetral to power the STC. Then pass the control wire that the broken thermostate used to control through the cooling relay (remove from thermostat and connect to STC relay posts). Then it should work. If you don't follow maybe try talking to an appliance repairer over a couple of homebrews and explain what you want to acheive. I imagine a total of <1 hours work

 

That's what I did and I cannot be happier, basically I replaced the original thermostat with the stc-100 and I didnt even have to cut the wires the GE 7.0 didnt have to be cut at all.

 

Awesome.. Thanks for posting this. I will be attempting this next week..

 

Did you bypass the original freezers controller, meaning the relay to the compressor? or did you wire between the constant coming in and relay?

 

Can you share what color wires from the freezer went to what on the controller.

I want to bypass the freezer thermostat and mount my stc1000 like you did?

 

I would like to do this as well. I've been futzing around with this all weekend and i can't get the unit to kick into cooling mode.

I am attempting to hook up cooling only, trying to hook up in-line to take the place of the thermostat.

 

This should do it for the STC1000, my controller happens to be a different model.

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Thanks, I did figure it out eventually.

 

Thanks to Ben for posting this, I did the direct wire and it's working great!

 

I did the direct wiring as well (I believe I got the idea from Trevster's build post). here is my little diagram I drew up (for a GE 7.0 cu model). Just mounted it by cutting a hole in a little piece of scrap metal with a dremel. Never understood why I'd want to keep the old controller in place.

 

Here's how I wired my Igloo FRF472 (build thread here). I'm guessing it's pretty much the same as any other keezer, aside for maybe some different wiring colors.
Also, I'm guessing that the run light could be bypassed. I decided to replace it with another light (120v) mounted in my custom faceplate (pics soon). It will be nice to use it to make sure the controller is working properly.

 

Another picture - it helped me to draw it out. I will be putting the STC-1000 in the collar, and will have the one extension cable routed through the back of the keezer/collar.

 

Benthehreat

I have wired the stc1000 to my chest freezer using your instructions and diagram. The only thing I did different was from the stc to the freezer I wired a female end to plug into my freezer. I had the unit wired differently and was getting power and the freezer was running but It wouldn't shut off. I found your post and re-wired and my freezer will not turn on. I know my wires are correct on both ends of the stc and per your instructions they are wired correctly into the stc. Do you have any suggestions?

 

Are you waiting the delay time before expecting the cooling relay to turn on? The cooling light will blink during the delay time and then turn solid when the cool relay closes.

Post a few photos of the wiring. It'll get sorted out.

 

The green wire going straight from the compressor to the outlet is the ground?

 

Yes, that's a Safety Ground wire.

Cheers!

 

thanks alot for the simple wiring diagram for those that need it! Mine is all hooked up and working great! I decided to go straight off of the main power wire about 2 feet from the plug as I did not want to tinker with the temp knob installed

 

perfect,
thanks again HBT!

 

How did you connect the temperature probe? Can you simply connect the freezer's temp probe up to the STC1000, or will I have to chance drilling through the freezer body and possibly hitting a freon line? I am currently running without a collar (pin lock kegs....) and tried to use the coarse temp adjust screw to get to my temp but I think the stock thermostat is toast.

 

Use the correct probe for the STC-1000 -- not the freezer's builtin probe.
I ran mine along the outside back of the freezer and just have the lid close over the wire.