Hard Wired STC-1000 Issues

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MrOrange

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So today I was helping a buddy hard wire his STC-1000 to his fridge for temperature control (cooling only). We wired the STC-1000 per the schematic below and had no luck getting it to kick on the compressor to the fridge. If you look at the schematic below we took wire number 10 which came from our plug and wired it to terminal number 1 on the STC-1000 which is L1 for the power. Then we took wire number 10X2 which is the neutral and wired it to terminal number 2 on the STC-1000 which is L2 for the power. I jumpered between terminal 1 and terminal 7 on the STC-1000 to supply power to the Hot side of the "cooling" set of contacts and I jumpered from terminal 2 on the STC-1000 to the fridge to supply the neutral. Then we ran wire number 11 from terminal 8 on the STC-1000 to the fridge. In my mind all of this should have worked out. Once the temperature probe got to the set point it should have closed the "cooling" set of contacts and kicked on the compressor to the fridge. Is there something wrong with my wiring or is there something I am missing? We know that the fridge works if I eliminate the STC-1000 and just wire nut everything together. I will post pictures of my physical wiring so you can double check what I have done (the wiring is sloppy, we made due with what we had haha). Please let me know if you have any insight into why this wouldn't be working. Thanks

Schematic.jpg


Wiring.jpg


STC-1000.jpg
 
Looks proper from here.
Does the "Cooling" LED come on at all?
If not, check your programming.
If it does, you might have a duff cooling relay...

Cheers!
 
I am not an electrician so this may be wrong. Are the wires from the receptacle reversed? White wire from the left side of the receptacle and the black wire from the right side. Black to #1 and white to #2?
 
Aside from potential safety issues, it wouldn't matter. It's AC, no polarity required. If some ******* at the factory somehow tied neutral to the chassis ground things could get exciting, but until someone got killed the compressor would run just fine :eek:

Cheers!
 
Just to make sure we don't have any potentia misunderstandings.

1. Are you trying to make a STC-setup, where you power the unmodified fridge? Just like plugging the fridge into a normal wall receptacle, but you plug in into a receptacle controlled by the STC?

2. Or, are you trying to bypass the fridge internal thermostat, and wire the STC straight on to the compressor?

If 1, then you wiring is correct. I bet that there is something with the internal thermostat in the fridge.
By doing it this (normal) way, you are only telling the fridge when to turn on, or off. This means that the internal thermostat in the fridge still has the last word when it comes to when to cool or not.
Make sure that the interal thermostat actually works, and that it is set low enough, it should be set to minimum temperature/maximum cooling.
If it's set to a higher temerperature (including offset between your STC-probe and the fridges probe) it will not cool, since you are only turning on the fridge, but the thermostat which has the last word, doesn't sense the fridge to be warm enough to engage the compressor.

Also check what day_trippr wrote, there might be a delay (default is 3 min) in the STC which you have forgotten/didn't know about.
 
Good Day I am not a sparky but by your first photo of your wiring it shows power going to 1 and 2

then it shows a wire jumping from 1 to 7

then it shows a wire going from 2 to the fridge

it should be power going in 1 and 2 and then going out 7 and 8 to the fridge

all the best

S_M

Schematic.jpg
 
Good Day I am not a sparky but by your first photo of your wiring it shows power going to 1 and 2

then it shows a wire jumping from 1 to 7

then it shows a wire going from 2 to the fridge

it should be power going in 1 and 2 and then going out 7 and 8 to the fridge

all the best

S_M

The wiring in the scheme is correct. STC only breaks one of the legs in a circuit. So you put hot in 7 and out 8, STC then breaks the hot. Neutral should come straight off the load (fridge) and back to neutral.
 
Looks proper from here.
Does the "Cooling" LED come on at all?
If not, check your programming.
If it does, you might have a duff cooling relay...

Cheers!

The cooling LED does come on and blinks when power is first applied to the STC. After a minute or two the light stops blinking and becomes steady. When this happens you can hear the STC "click" as if it is pulling in a coil to close the set of cooling contacts. I have verified that the fridge thermostat works because we were able to unwire the stc and wire the fridge back up and it came on and operated just fine. I was wondering if it was a bad unit but i was hoping for an easy wiring fix. Thanks for all the input
 
The wiring in the scheme is correct. STC only breaks one of the leads in a circuit. So you put hot in 7 and out 8, STC then breaks the hot. Neutral should come straight off the load (fridge) and back to neutral.


if you say so, but I know the four I have and am using has power going in 1 and 2

the power coming out 7 and 8 for cooling with 5 and 6 for heating

with no with wiring jumping from 1 and 2 to anywhere

just like the picture on the STC 1000

all the best

S_M

STC-1000.jpg
 
Good Day I am not a sparky but by your first photo of your wiring it shows power going to 1 and 2

then it shows a wire jumping from 1 to 7

then it shows a wire going from 2 to the fridge

it should be power going in 1 and 2 and then going out 7 and 8 to the fridge

all the best

S_M

The wire that jumps from terminal 1 to terminal 7 is my hot wire to supply voltage to the set of contacts. The wire that comes from 2 and goes to the fridge is my neutral. If the STC operates correctly, when the contacts are pulled in and it should complete the circuit to the fridge and turn on the compressor.
 
The wire that jumps from terminal 1 to terminal 7 is my hot wire to supply voltage to the set of contacts. The wire that comes from 2 and goes to the fridge is my neutral. If the STC operates correctly, when the contacts are pulled in and it should complete the circuit to the fridge and turn on the compressor.

the power on an STC1000 goes in 1 and 2 and then goes out 7 and 8 or 5 and 6

to turn on and off whatever you want the switching is done inside the STC1000

but good luck and all the best

S_M
 
if you say so, but I know the four I have and am using has power going in 1 and 2

the power coming out 7 and 8 for cooling with 5 and 6 for heating

with no with wiring jumping from 1 and 2 to anywhere

just like the picture on the STC 1000

all the best

S_M

It doesn't matter if they are jumped within the STC or not. The point is that you can distribute both of the legs the way you want. As long as hot is before the load (fridge) and neutral is after the load. It's just making splitters which carry the legs to and from the correct terminals in your wall.

He could skip the jumping in the STC, but would then need to split each leg some other place. Like I said STC operates by just "cutting" one of the legs, which would make it an uncomplete circuit (no power passes). The other side is connected all the way down to the receptacle in your wall outlet. When the STC engages is connects point 5&6 or 7&8 together, so you have a complete circuit, and electricity can pass. It's like a switch on only one of the legs in the circuit.

There's several ways of doing this, this is one of them.
 
the power on an STC1000 goes in 1 and 2 and then goes out 7 and 8 or 5 and 6

to turn on and off whatever you want the switching is done inside the STC1000

but good luck and all the best

S_M

It doesn't go "out" 7 and 8. The power goes "in" seven, and "out" 8, in between 7 and 8 there is a switch.
 
The wire that jumps from terminal 1 to terminal 7 is my hot wire to supply voltage to the set of contacts. The wire that comes from 2 and goes to the fridge is my neutral. If the STC operates correctly, when the contacts are pulled in and it should complete the circuit to the fridge and turn on the compressor.

Smellyglove's posts here are spot on. Reread the post with "1. or 2." and answer those questions in regards to your fridge setup. Some new electronic fridges have a lengthy startup/initialization process before the compressor comes on. When the cooling relay clicks, check that there's actually power on the fridge at that time.
 
you are indeed right just looked inside mine

mine are wired to outlets

I stand corrected

S_M


Do you understand the basics? Just to make sure you don't short a friends or your next STC-build :) I can give you a simple analogy to try to make it clear.
 
you are indeed right just looked inside mine

mine are wired to outlets

I stand corrected

S_M

It seems like the heat and cool are reversed on the schematics you posted. Unless there are different versions of the STC out there.

Heat should be out of 6, cool should be out of 8. At least they are on all of my four STCs, aquired from the same source.
 
The cooling LED does come on and blinks when power is first applied to the STC. After a minute or two the light stops blinking and becomes steady. When this happens you can hear the STC "click" as if it is pulling in a coil to close the set of cooling contacts. I have verified that the fridge thermostat works because we were able to unwire the stc and wire the fridge back up and it came on and operated just fine. I was wondering if it was a bad unit but i was hoping for an easy wiring fix. Thanks for all the input
After hearing the "click", can you verify that there is 120vac across 11 and 10X2? If yes, then the STC1000 wiring and functionality is good and there is another issue.

Given the numbering on your diagram, is it a good assumption that you have a schematic of the fridge? If yes, then post it here.

You may need to simply bypass the fridge's internal thermostat.
 
Do you understand the basics? Just to make sure you don't short a friends or your next STC-build :) I can give you a simple analogy to try to make it clear.

I am good but thanks for the offer

I should have looked at mine before I posted so as not to confuse the OP

trying to brew , work and post before coffee

all the best

S_M
 
I am good but thanks for the offer

I should have looked at mine before I posted so as not to confuse the OP

trying to brew , work and post before coffee

all the best

S_M

Still. Check out my post right after the one you quoted in regards to the wiring scheme you posted. For future readers :)
 
Have you solved the problem? I as well wired my stc the same as you(power in 1, 1 jumped to 7, 8 to the frezzer, neutral to 2 and out 2 to the freezer. When I re wire it back to normal it works fine. When I trouble shoot it with the volt meter I get 120 in 1 and obviously 7 being jumpered but no power out of 8. Am I missing something there or wtf? I've also try wiring it hot in 1, neutral in 2, hot load side 8, neutral load side out 7 nothing works
 
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