STC-1000 Temp contoller stuck on heat!!!

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eryk4381

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Hey guys,

Wondering if anyone has had this issue before with this temp controller.
I have my build all set up and had a beer in the fridge fermenter. It was regulating the hot and cold great. Then after two days i checked the temp and it said -88 degrees and apparently had been heating ALL DAY!!!!! Took my beer up to 79 degrees!! GRRRR..

I thought it may be just a random thing so I instantly cooled it back down then reset the temperature back to what I wanted. Two days after it stuck on -14 degrees and was heating again.

WTF. Do I need a new one? It seems to work fine except for these random occurrences.

Thanks for any help!
 
How big of a heater are you using? Is it within the ratings of the contacts?
I'm going to look at what mine is rated for.
 
I'm not really familiar with that controller. Does it have an indicator on the front that tells you if the output is on? Indicator off and still heating is more than likely a welded contact.
 
I missed the part in the original post about it reading -88:eek:. I was thinking stuck heater contacts orginally
 
I'm not really familiar with that controller. Does it have an indicator on the front that tells you if the output is on? Indicator off and still heating is more than likely a welded contact.

It should have that indicator on the front.
 
This is exactly why I tried warning people off of overkill heater solutions in another thread. You could open up the fridge and find a melted liner and other nasty stuff.
 
I'm not really familiar with that controller. Does it have an indicator on the front that tells you if the output is on? Indicator off and still heating is more than likely a welded contact.


It seems like an error type message but instead of a EE error it supposed to give when there's a short or something it just reads a completely off temp and trys to regulate that with heating until it gets back to what I programmed it to keep the temp at.. so judging by what i just wrote :) i think that is starting to sound more like the probe.
 
This is exactly why I tried warning people off of overkill heater solutions in another thread. You could open up the fridge and find a melted liner and other nasty stuff.

So you have seen something like this before then???
I only have a 75 watt infrared bulb in there.
 
Again not being familiar with the controller, is there a possibility that the wires on the probe are reversed?
 
It seems like an error type message but instead of a EE error it supposed to give when there's a short or something it just reads a completely off temp and trys to regulate that with heating until it gets back to what I programmed it to keep the temp at.. so judging by what i just wrote :) i think that is starting to sound more like the probe.
Do you have an ohm meter? Check the resistance at room temperature. I can then check mine to get a reading and see if they are in the same ballpark.
 
So you have seen something like this before then???
I only have a 75 watt infrared bulb in there.
I did appliance repair for over 30 years. Yes, I have. 75 isn't too bad but I wouldn't go over a day without checking it to be safe. It all depends on application and temperature extremes. I have an old heating pad I use. It takes a couple days sometimes to get up to temp in the winter but it works. In my application, in my basement refrigerator fermentation chamber I'd be comfortable that 25 watts is enough. The small space heaters are overkill at 200 watts but at least come with their own thermostats as a backup.

In my cases the damage is 'usually' confined to the area of the light bulb. There was also some wall melting in some of the older freezers from the icemakers. Just point the 75 watt bulb away from surfaces.

Keep in mind the units I worked on were actively trying to cool which helped.
 
Since the controller is behaving properly given what it thinks the temperature is, this doesn't sound like a wiring mistake. It's an NTC probe, so a super low temp means you're getting a lot of extra resistance. If this is only happening sporadically, perhaps a short somewhere in the cable? Or maybe a bad connection where the probe connects to the controller? Did you wire some kind of plug into the probe cable, or does it plug directly into the back of the controller?
 
since the controller is behaving properly given what it thinks the temperature is, this doesn't sound like a wiring mistake...
=?
.... Or maybe a bad connection where the probe connects to the controller? Did you wire some kind of plug into the probe cable, or does it plug directly into the back of the controller?
 
Do you have an ohm meter? Check the resistance at room temperature. I can then check mine to get a reading and see if they are in the same ballpark.

Resistance with the wire probe you mean? I can check that. Do you think it may have a fault in the probe wire?
 
Since the controller is behaving properly given what it thinks the temperature is, this doesn't sound like a wiring mistake. It's an NTC probe, so a super low temp means you're getting a lot of extra resistance. If this is only happening sporadically, perhaps a short somewhere in the cable? Or maybe a bad connection where the probe connects to the controller? Did you wire some kind of plug into the probe cable, or does it plug directly into the back of the controller?

Yeah its directly connected to the controller. The wire could have been pinch or something and giving a random read to give the temp controller such odds results. Maybe moisture in the fridge caused a resistance fault in the wire and stuck the temp controller with and bad read?
 
If you wired it up to control an outlet like most of the DIY forums did you ensure you broke the connector bridge on the side that ties the the two post on that side together? if not that could cause your heat to run the same time it should be cooling? just a thought to check
 
If you wired it up to control an outlet like most of the DIY forums did you ensure you broke the connector bridge on the side that ties the the two post on that side together? if not that could cause your heat to run the same time it should be cooling? just a thought to check

Yep. I made sure the connection was broken. Just to make it clear in case I confused anyone, the heat doesn't come on at the same time as the cooling. The process with switching from heating to cooling works just as it should. The only issue is that the temp should read probably about 65 degrees and somehow the temp controller is reading that it's 14 degrees which is probably impossible.
 
....i checked the temp and it said -88 degrees and apparently had been heating ALL DAY!!!!! Took my beer up to 79 degrees!! GRRRR..

I thought it may be just a random thing so I instantly cooled it back down then reset the temperature back to what I wanted. Two days after it stuck on -14 degrees and was heating again...

.... The only issue is that the temp should read probably about 65 degrees and somehow the temp controller is reading that it's 14 degrees which is probably impossible.
I'm a bit confused. Are you mixing temperature units in your discussion?

14deg C = 57deg F
65deg C = 149deg F
18deg C = 65deg F
-10deg C = 14deg F

I would suggest checking the calibration of your probe/controller. Does it read 0deg C in a cup of ice water?
 
I am gathering that your temp is reading way lower than actual.

I think you should focus on discontinuity in your temp probe first. Make sure you have a good connection with your temp probe wires and terminal strip. Also make sure your temp probe wire is not damaged.
 
I'm a bit confused. Are you mixing temperature units in your discussion?

14deg C = 57deg F
65deg C = 149deg F
18deg C = 65deg F
-10deg C = 14deg F

I would suggest checking the calibration of your probe/controller. Does it read 0deg C in a cup of ice water?

I was mixing degree measurements, sorry. When I said -88 degrees i meant Celsius.
The next time it misread tempreture it was -14 degrees Celsius as well.

"....i checked the temp and it said -88 degrees and apparently had been heating ALL DAY!!!!! Took my beer up to 79 degrees Fahrenheit!! GRRRR.."
 
Well, someone questioned it. We could simply compare readings around room temperature if you want.

OK sorry it took so long to get the resistance measurement. I took out my probe from the install and checked it at room temp. I'm reading 11.3K ohms.

What is everyone else reading on their probes???..
Thanks again for the help.
 
OK sorry it took so long to get the resistance measurement. I took out my probe from the install and checked it at room temp. I'm reading 11.3K ohms.

What is everyone else reading on their probes???..
Thanks again for the help.

Sounds about right. It's a 10K ohm resistor, so it should read 10K at 25°C (77°F). Your room temp is likely slightly cooler, hence the slightly higher resistance.

Did you try wiggling the wire at every point along it's length? If the probe wires got pinched or something, doing that would show a huge jump in the resistance. With the probe connected to controller, did you try wiggling the wires right at the contacts to see if it caused any changes in the readout?
 
Sounds about right. It's a 10K ohm resistor, so it should read 10K at 25°C (77°F). Your room temp is likely slightly cooler, hence the slightly higher resistance.

Did you try wiggling the wire at every point along it's length? If the probe wires got pinched or something, doing that would show a huge jump in the resistance. With the probe connected to controller, did you try wiggling the wires right at the contacts to see if it caused any changes in the readout?

Looks like wiggling the wire only moves it slightly so it can't be a default in the wire.

When I wore it back up i will try wiggling them in the controller to see if it changes at all.
 
When you hook it back up, make sure that you only have wire and not insulation in the terminal block.
 
When you hook it back up, make sure that you only have wire and not insulation in the terminal block.

So i re-attached the sensor wires to the temp controller and ran it a few days with nothing in it for testing purposes. No issues.

I am now cold crashing a Pale Ale with no temp issues as well either. I'm going to say it was probably the contact from the sensor to the controller in some way as that is the only thing I changed. Could have been the insulation causing a short but at least it works great now!! Thanks guys for all your help
 
I'm glad to hear it is working. I'm getting ready to build one of these for my fermentation chamber but I am going to use SSR's to switch the heat and cooling so there will be less wear and tear on the board mounted relays.
 
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