STC 1000 temp controller Keezer, kegerator, fermenter

[Dawai]

Hi.
I just ordered a STC 1000. http://www.tradeger.co.za/pdf/stc1000_operating_manual.pdf
(edit) found the pdf operational manual there, it seems to contradict what I read on another interpretation of "chinglish" translation. Please read and confirm this unit's contacts rating can handle your "heating or cooling load amperage". By overloading the contacts you may burn unit out prematurely. My suggestion if you doubt the load you are putting on to add a external relay.

The STC 1000 seems to be the "Simple and cheap temp controller" most the home brewers are using on youtube, "many telling others how to hook it up for non-electricians". I won't go into that, if you are having trouble I would be glad to help you if I can. (If I have time)

NOTE, the STC 1000 has "relay contact" ratings of 5 amps at 120 volts. That would be fine to control a relay.. but.. a normal refrigerator used to require a 15 amp dedicated circuit (been a long time since I wired a house). Plus a "electric motor" ie: compressor draws 600% inrush of nameplate during the first milliseconds of starting. This tells you that the "contacts" are not rated to control a big motor load starting up.. the "bright flash" inside the 8 pin relay currently turning my freezer on and off confirms this. It might work for a while, but is not rated for the job.
For reliability, long service a external relay with larger contacts must be used. Like a air conditioner relay, or large relay for turning heating or motors on and off. This would have adequate contact surfaces and be made to make and break the load without burning up over a period of time, the arcing - failing contacts will also damage the compressor windings. You could use a large SSR, but then you would need a way to turn it on and off since most the ones I have seen are "low 3-28vdc" voltage on the trigger side of the relay (No SSR output on the unit), I suggest a small furnace style contactor with the 120 coil, tied with a 120 hot into one side of the contacts and the output side to the contactor. THE contacts in the external contactor relay can then turn your fridge, or heater, or?? on and off. I know, it's more money for parts, more complexity but.. rated for the job.

"Why I noticed this". (if you don't care you can skip this part)
Okay, I "stuck" my pid control off my kettle pot onto the new deep freeze for my ball lock kegs, being half blind I put the wiring that was on the type J thermocouple probe over onto it. It was working, but I had never calibrated it.

"Instrument tech" note, Thermocouples require special thermocouple wire, the only temp sensor I know of that can use "normal" copper wire is a RTD. The thermocouple works by "dissimilar metals" normally welded into a bead on the end, the two different metals "push on each other" causing a minor voltage & current to flow. If you add another metal to the circuit, say copper, you just added more dissimilar metals and are generating a unknown calibration to your PID temperature controller. It may appear to work, but as I assure you it may crash horribly wrong. Even switches or terminal strips can be incorrect, the thermocouple wire needs to go directly to the instrument. Even then the internal tuning compensates for the terminals on the back of the PID.
Even thou this was hammered into my head since the 70s, I did it anyways and near lost my beer to freezing by not paying attention. I assumed.. it was correct.

The Barber colman digital control has been around here since the 80s. Small and can do many different control schemes from following a signal to controlling, alarming. It has both SSR outputs and relay inside. I tried to program it, without a booklet on memory to use the SSR to turn on the cooling, would not do it. I had to "fix a external relay" to handle the current of the freezer compressor. That is what triggered the notice of all the Home brewers using the simpler STC 1000 (which I ordered one of off ebay)
I also ordered a backup PID off ebay to control the "kettle" and build a new control box for it. I think that barber colman unit will be on a pvc welder I am building to turn the heater on and off. ($15 conical fermenter from a HDPE blue 15 gallon barrel) And a shaper oven, and..

 

[raouliii]

The STC1000 has internal relays rated at 15A/125VAC and has been used in many keezers, kegerators and fermenters for years with no problems. As with any relay device, they may fail at some point due to contact degradation, but for $20, they are still a very inexpensive solution.

 

[Dawai]

Very neat, what I wanted to see. I too take things apart to see how they work.

A tiny relay module inside. In the past I've not had much luck with chinese electrical items. Insulation on HF tools is normally bad, one guy on a machinist site recommended taking a Lathe motor from a major company apart and having the armature re-dipped in varnish. (grizzly tools)

I've found four different ratings on four different websites. One site stated it had 5 amps at 120 volts. (warning bells went off)

Yes, at that price, buy two or more. AND... if you got a dead one? that 12vdc coil power on that tiny relay could fire a SSR..

 

[kayakman]

The STC1000 uses an NTC ( or thermistor ) type sensor, not a thermocouple. This is why sensor leads can be extended without special wire.

 

[Dawai]

AND>>> Simple.. it has a compressor delay made into it, you just alter the time delay. WHEN it is in delay mode the light flashes instead of on all the time.

RE: the high dollar Barber colman unit currently on mine is kicking my compressor on and off as it bounces around the setpoint, possibly when the neighbor keys his CB radio?? or?? This is bad.. will burn up any kind of motor to start and stop it too often. This small complex unit has hundreds of menu options on the programming, not just simple. Simple is better most the time.

USPS has mine somewhere around Washington State... in route here. I wish I had purchased 2 of them, I got a old refrigerator that will not freeze, but would make a good lager fermenter.

I wonder why there is so many conflicting manuals on this unit??? Makes me want to take mine apart to see if it has the "good" relays inside it. Is it the "chinglish" translation to english?

 

[raouliii]

.......This is bad.. will burn up any kind of motor to start and stop it too often......

What makes short cycling a compressor bad is that when pressures within the system have not had enough time to equalize and the compressor starts up against this high pressure, large current spikes and extreme wear on the components are the result.

......I wonder why there is so many conflicting manuals on this unit??? Makes me want to take mine apart to see if it has the "good" relays inside it......

The manual you linked to has basically the same information as on the relay in the photo I posted. 10A/277(250VAC)

 

[Dawai]

Hi raouliii

Would you happen to have anymore internal pictures? Thou mine is a 110 volt unit, as needed, I would like to see if the 220/110 control voltage swaps via jumper or ?? (Grampa got pretty mad at me for taking his railroad watch apart) I still like to look inside.

Mine is still enroute from ebay.

I understand from another post here the thermistor is 10K @ 25C. Altering the resistance via longer wiring will slightly affect calibration, that is why Some RTD's have 3 wires, two are connected to the same terminal in the RTD sensor, the instrument measures the resistance of the two wires and takes that into the equasion.

Is F-4 the way to alter calibration? Any onboard trim pots?

Most people building a "fermenter", do they use the light bulb for heat, the cooling portion of the fridge for chilling? (no heating problem here lately)

Why are these people wiring these into receptacles?? why not just alter the compressor lines, in my deep freeze the thermostat breaks the line power to the compressor, so you could take the main cord, cut it, splice all the incoming-exit neutrals together, break the 110 feed through the cooling contacts, and power the compressor hot with the N.O. cooling contact. (now that it has been established it will run a freezer) No receptacles needed, unit mounted on the keezer where the thermostat used to be.

Receptacles Mean, some "grandkid" or "wife, maid" or other will attempt to plug in a "vacuum, drill, battery charger, boombox, cell phone charger, molecular de-energizer" into the circuit and trip it. (making my beer hot, and my neck) Matter of a fact knowing this makes you want to wire nut the keezer directly into the dedicated wall circuit and take out that receptacle also.

Here in America, more fires are caused by plugs partially pulled from receptacles than about any other reason, other than "user modified" items. When you pull a high amperage plug slightly from the receptacle, it is no longer adequate to carry 15 amps, will overheat, if PVC-cheap receptacle, it will flame up.. the wall will burn.. the house will follow. In the 70s I woke up in a house trailer, the wall was on fire, a simple box fan plugged in running fanning the flames. That was exciting.

 

[Misplaced_Canuck]

the reason is that you'd be modifying the fridge. Some people don't want to do that, and they prefer to just have the fridge unmodified. I'm one of those.

MC

 

[raouliii]

...Would you happen to have anymore internal pictures? Thou mine is a 110 volt unit, as needed, I would like to see if the 220/110 control voltage swaps via jumper or ??.... Any onboard trim pots?....

No jumpers. No pots. The transformer dictates AC voltage:

...Why are these people wiring these into receptacles?? why not just alter the compressor lines,...

I hard-wired mine into my fermentation chamber because I'm comfortable with modifying/customizing electrical but many here aren't, nor do they want to modify their cooler/keezer. The receptacle route results in a standalone, easily reversable, easily transferable controller. To each his own.

 

[Dawai]

Well..

that explains that, thou.. it is simpler without a receptacle, less connections to fail. Most people should realize that.

Thank you.. Mine is up and running, I plasma cut a stainless plate to replace the factory thermostat, Stuck it in, zipped up the clamps, broke the hot wire with the contacts, ran a jumper from the in-wire, a jumper from the neutral to run the instrument pwr. Simple, no problems holding a 5C temp. (checking with a thermometer) Almost looks factory if the plate was not shiny.

30-45 minutes including building the plate, longer to file the burrs than to wire it. I explained to the wife it didn't have to come out to convert back to a fridge, (if I get KO'ed on the bike).. just lower the temp on the meter.

NOW.. why is my dark beer so foamy out of the keg.. (will search others posts for the same question) I got a home made tap (1/4" ball valve).. will build a stainless ramp on the lid to hold a real tap. I think I need to go to a smaller line, thou the Pilsner decanted just fine. Now should that "thing" going on top of the lid look like a Harley gas tank, a fender, or a tunnel ram hood scoop off a old race car? Maybe a vinyl wrap to match??

 

[Misplaced_Canuck]

that explains that, thou.. it is simpler without a receptacle, less connections to fail. Most people should realize that.

Well I also use my STC-1000 for heating, when fermenting in the 60's, and the fridge is in the garage in the winter in the 40-50's. So I'd have to hard-wire a heater lamp as part of the circuit.

Simpler without receptacle, yes; less connections to fail, yes. But the likeliness of the receptacle/wiring to fail is not much different than a standard house receptacle. It does happen, but not that often at all.

Not only that, but I can also use the stand-alone STC-1000 box with other devices, which I have done in the past: e.g.: I used a space heater to keep a spare bathroom at 68F in the winter.

MC

 

[MindenMan]

My freezer is 5 cubic feet, and when it was winter I tried using the smallest amount of heater I could find. 60w bulb, way too big, 40w, still too hot, 25 watt appliance bulb, still too hot, even using a cfl of 60 watt equiv was too hot. The cfl bulb drew 14 watts and was still too much. I guess my point is unless your keezer is gigantic, IMHO, a small light bulb will be more than enough heat.

 

[whalerockbrewing1943]

The analog unit has 3 wires going to it...green which is safety, black which is hot or line, and blue which is neutral. Can I wire my STC-1000 to the 3 wires and how...I have literally tried all combinations. I get dial readings and programmability, but when the cool lite stops flashing, the unit does not turn on (set STC-1000 at 4 degrees centigrade.

I am baffled.....all I see is STC-1000s used in the power line circuit coming to the kegerator. It should be so simple it's baffling....Edgestar is absolutely NO HELP

Jim

 

[raouliii]

The analog unit has 3 wires going to it...green which is safety, black which is hot or line, and blue which is neutral. Can I wire my STC-1000 to the 3 wires and how...I have literally tried all combinations. I get dial readings and programmability, but when the cool lite stops flashing, the unit does not turn on (set STC-1000 at 4 degrees centigrade.

I am baffled.....all I see is STC-1000s used in the power line circuit coming to the kegerator. It should be so simple it's baffling....Edgestar is absolutely NO HELP

Jim

I'm guessing its not as simple as you believe it should be. Photos of the wired, existing, thermostat would be useful. A schematic would also be great if there was one available.

 

[Holgar]

I realize this is an old thread- but i have something very similar that I need some help with.

I'm trying to replace the manual dial thermostat with the STC/ITC-1000. I have an assumed wiring diagram that I need to do and the current wiring diagram from the freezer. Can someone confirm this is correct?

 

[day_trippr]

One of the worst drawn wiring diagrams I've ever seen for a consumer appliance. And I'm a fossil.

Just...awful.

I'm pretty sure there really isn't a short path from hot to ground at the Defrost Timer as drawn.

And if Blk = Black, what does "B" equal??

Anyway...If I'm getting it right, the actual thermostat is bounded by the drawn box, and you want to disconnect those two wires and route them through the "Cold Side" relay of your controller.
One of those wires is likely Red; the other may be Brown, or Black. Stupid key doesn't cover "B".



Note that you could probably just bridge the existing connections while setting the thermostat to its coldest setting, presuming your controller cut-in temp will always be above the coldest thermostat setting...

Cheers!

 

[raouliii]

.....I'm pretty sure there really isn't a short path from hot to ground at the Defrost Timer as drawn.

And if Blk = Black, what does "B" equal??

....

I'm not seeing the hot to ground issue. There is a defrost timer motor between "1" and "3".

Based on Holgar's posted drawing and references on the schematic, "B" is likely to be blue.

Holgars's drawing would then be correct except the red conductor at terminal 1 should be white.

 

[Holgar]

Thanks guys.

Going to take apart the dial thermostat on the inside of the freezer this weekend. I'm praying I only find three wires (Blue / Red / Green).

If I connect the blue/red directly, the compressor should come on (just like a thermostat in a house). If that's the case, then the STC/ITC should work as it acts like a switch. Hopefully the ground wire is easily identifiable (by color or how its attached to the existing thermostat).

As for the mains wiring- my oversight... it should indeed be a white wire (I plan on wiring this to the mains of the freezer to only have one cord out the back).

[nervous as this is my second attempt at this build - first was killed by a rogue freon line...]

 

[Holgar]

Took apart everything-

Turns out the thermostat was a 110v thermocouple (i think) that was simply acting as a switch and carrying real current (vs. a thermostat). The ITC was a perfect application for this and is working well.

I now need to find the right placement of the temp probe. I wrapped it around a can of beer, then foil taped it - placing the unit in the top shelf of the door (hoping this would eliminate some of the warm beer line up top, cold beer on the bottom issues). I feel the fridge is cycling more than ideal, so might need to look into calibration of the ITC next.