STC-1000 in a fridge

[FatDragon]

Recently got a new fridge for fermentation and freezing. I've got an STC-1000 I intend to wire up in place of the fridge's thermostat while leaving the freezer to do its regular work. However, I'm kind've an idiot when it comes to these things - I was able to set up my external STC-1000 box for my old ferm chamber thanks to help from here, but my electrical knowledge is limited. I know enough to not zap myself, and I know enough to buy a domestic Chinese STC-1000 for my domestic Chinese fridge (220-240v), but that's about as far as I get. I'll add that I can replace the STC-1000 with any of Elitech's myriad other temp controllers if that will help.

So...

The Goal: Wire a temp controller up in a new fridge, with cooling and heating (probably some kind of heat tape or wire). Leave the freezer functioning normally.

The Equipment: TCL BCD-389BR62 Fridge, STC-1000 (or other Elitech temp controller), some kind of heating element - tape, wire, bulb+fan, etc.

The Dilemma: Like Jon Snow, I know nothing.

I unscrewed the light/thermostat fixture in the fridge to get a look at the internals - here's a pic:

 

[EJay]

Well, for starters, the freezer probably isn't separate, so don't count on being able to both do fermentation and freezing in it at the same time. They probably run off the same compressor and use a single thermostat to control both.

 

[rlmiller10]

What Ejay said. The temp is controlled by the thermostat in the fridge and the freezer gets enough cold to stay frozen just from the fridge being kept cold. Rather than rewiring the controller on the fridge it would be the same results using it as an external controller and plugging the fridge into an STC-1000 controlled outlet.

 

[FatDragon]

A part of me died when I read those responses. I know it's my fault for not doing adequate research, but is there any way to salvage this? The fridge can't be returned (packaging was cut open and thrown away by the delivery company and the plastic cover of the light - which provided access to a couple screws for the thermostat assembly - couldn't be removed without breaking one of the tabs) and I'd probably take a loss of at least 25% of the cost (amounting to ~$100) if I sold it. Also, my wife would hold this over my head for years if I had to abandon the fridge and start over.

The intention is to ferment beer (ale temps) in the top half and freeze meats, sausages, bulk cooked foods like chili and chicken stock, maybe homemade cheese, etc. in the freezer. Our kitchen fridge's freezer is too small for the amount of stuff we want to freeze but our apartment is too small to justify a freezer and a multiple-vessel fermentation chamber. Is there any hope of making something like this possible, maybe with modifications to the fridge, or do I need to start being extra nice to my wife so she doesn't blow up when I break the news that I've got to sell the fridge and try something different?

 

[rlmiller10]

Unless it is a dual compressor fridge, something only common on very high end units, I don't think there is any way. The same compressor and same coils cool both fridge and freezer unit. Keeping the fridge unit at 66 F for fermenting will not keep the freezer part frozen.

You could test it by using your old external STC-1000, put the probe in the fridge compartment and plug in the fridge. It will give you exactly the same function as if you wired the unit to control the internal thermostat. It would be interesting to see what the freezer temp could be kept down to.

 

[rlmiller10]

Oh, and buy your wife flowers just in case.

 

[FatDragon]

Oh, and buy your wife flowers just in case.

I've gotten better at it lately, so hopefully there's already some goodwill stored up. However I handle this, it's gonna take a long time to live it down. Kicking myself over doing something stupid I can live with, but my wife kicks harder, more consistently, and for a longer time...

The worst part is that I didn't do my research in advance because I was concerned about catching a one-day sale. Turns out (as I should have known) the sale price was $15 less than the everyday price.

 

[bleme]

I got a used fridge on Craigslist with the intention of fermenting in it, but it was so handy having that extra freezer space that I ended up keeping it at normal temps and fermenting in my old rope tub. It is currently keeping a couple cases of beer cold but I plan to put a couple of kegs in there eventually.

Moral of the story, it doesn't have to be a total loss...

 

[FatDragon]

I got a used fridge on Craigslist with the intention of fermenting in it, but it was so handy having that extra freezer space that I ended up keeping it at normal temps and fermenting in my old rope tub. It is currently keeping a couple cases of beer cold but I plan to put a couple of kegs in there eventually.

Moral of the story, it doesn't have to be a total loss...

I can think of a few ways I could use the fridge that would work out roughly like this, but we live in an apartment and the wife signed off on this as a freezer/fermenter; if I can't get both uses out of it, it's going to be a constant sore spot. Life is probably going to be easier if I just admit I screwed up, sell it as brand-new secondhand, and try again after some better research.

I'm going to spend a lot of time squinting at it like I'm thinking really hard and genuinely trying to figure out if there's a way to salvage things as they are, but bailing is probably going to be the answer...

 

[bleme]

My wife wasn't thrilled with me buying the fridge in the first place, but now she is probably more attached to it than I am. As long as she gets the freezer, she could care less what I use the fridge for.

 

[PlexVector]

@FatDragon,
I'm guessing from the picture and link, but it looks like the bottom is the freezer and the top is the frig, so it has to have a fan to pull the cold dense air from the freezer to the frig and the thermostat controls the fan. If this is the case then you only need to control the fan with the controller for cold temps in the frig if you can figure out how the fan is presently controlled.

 

[FatDragon]

My wife wasn't thrilled with me buying the fridge in the first place, but now she is probably more attached to it than I am. As long as she gets the freezer, she could care less what I use the fridge for.

Unfortunately, I'm the food half of our household. Filling the fermentation fridge and the deep freeze are both my job. I get a pass for both if I keep us in tasty food and I can keep convincing her that I might one day make money brewing, but if we have this huge fridge and it's not fulfilling both of my intended purposes, I'm in the doghouse.

@FatDragon,
I'm guessing from the picture and link, but it looks like the bottom is the freezer and the top is the frig, so it has to have a fan to pull the cold dense air from the freezer to the frig and the thermostat controls the fan. If this is the case then you only need to control the fan with the controller for cold temps in the frig if you can figure out how the fan is presently controlled.

You're making me a (potentially) very happy man...

Bear with me here -

1. If the compressor chills the freezer and a fan draws cold air into the fridge, controlling the fan controls the fridge temp (as you've suggested - I'll note that there is a fan in the rear of the fridge chamber so this seems hopeful).

2. If controlling the fan controls the fridge temp, the thermostat in the fridge controls the fan.

3. Therefore, replacing the thermostat in the fridge with an STC-1000 would allow me to control the fridge temp without affecting the freezer.

4. In the event that the thermostat in the fridge chamber does control the compressor and not just the fan, I would still theoretically only need to attach my STC to the fan's power wire to control the fan and thus the upper chamber's temperature.

Am I onto something here?

If so, we're back at step one, where I could use the advice of some more electrically-minded HBTers to help me identify the wiring that's currently in place so I can swap in my STC-1000.

 

[PlexVector]

I unscrewed the light/thermostat fixture in the fridge to get a look at the internals - here's a pic:
TCL BCD-389BR62 Fridge

Is this the only control for temperature control for the frig/freezer? If so then I would assume that the capillary tube is going to the freezer section and another mechanical sensor for the frig section is in the metal box seen in the picture and the knob is calibrated to control both compressor and frig setting at the same time. If this is the case then there should be a wire that controls the fan and a wire that controls the compressor coming out of the metal box behind the knob.

- How many wires are connected to the metal box behind the knob?

- How does the manual explain the control of freezer and frig temp control? this should give us a hint as to how it all may be wired.

- I can figure most of wiring diagram, but if you could translate it that could help.

 

[FatDragon]

Some of the translations were done through Bing because I don't know technical electrical terms so their guess is probably better than mine. The untranslated one in the middle of the right edge starts with "pressure" and ends with "machine", but the middle character is incomprehensible to me because of the jpg compression - I can't even figure it out with a stroke-recognition app.

Unfortunately, after work my wife and I are going straight to the airport for a weekend in Shanghai, so I won't be able to check anything for the next couple days. I don't recall a temp controller in the freezer, but I'll admit I haven't looked since I've focused my attention on the upper chamber (the pictures on the sale page make it look like there isn't a customer-accessible controller there, but it seems like there would be a built-in thermostat to make sure the freezer freezes at its advertised rate regardless of fridge setting).

Per the photo in my first post, there are five connectors into the current controller - one semi-rigid, non-insulated, silver-colored wire that you can clearly see, three normal-size connectors with blue insulation, and one double-wide L-shaped connector with blue insulation. I'm afraid I can't recall offhand how many wires lead to each connector - I'll have to look again when I get home in a few days.

 

[PlexVector]

Some of the translations were done through Bing because I don't know technical electrical terms so their guess is probably better than mine. The untranslated one in the middle of the right edge starts with "pressure" and ends with "machine", but the middle character is incomprehensible to me because of the jpg compression - I can't even figure it out with a stroke-recognition app.

Unfortunately, after work my wife and I are going straight to the airport for a weekend in Shanghai, so I won't be able to check anything for the next couple days. I don't recall a temp controller in the freezer, but I'll admit I haven't looked since I've focused my attention on the upper chamber (the pictures on the sale page make it look like there isn't a customer-accessible controller there, but it seems like there would be a built-in thermostat to make sure the freezer freezes at its advertised rate regardless of fridge setting).

Per the photo in my first post, there are five connectors into the current controller - one semi-rigid, non-insulated, silver-colored wire that you can clearly see, three normal-size connectors with blue insulation, and one double-wide L-shaped connector with blue insulation. I'm afraid I can't recall offhand how many wires lead to each connector - I'll have to look again when I get home in a few days.

I was in Shanghai about 12 years ago on business. Looking out the hotel window the construction cranes were everywhere. Have fun! we'll figure this out when you get back.



Heat protector: Thermal protection for the compressor

Temperature controller: Thermostat, which has to be the metal box in the frig. The semi-rigid, non-insulated, silver-colored wire is a tube that goes to the freezer, which I would expect to be the freezer temp sensor.

Self-induction on/off / heater: This has to be the defrost heater on the evaporator coils. Not sure how the switch is controlled. usually it is controlled by a little motor that cycles the defroster, but the way its wired in the diagram does not make sense to me.

Turning plate heater: This heater is on all the time, which also does not make sense to me. based on the name possibly related to the ice maker.

Light: I originally thought this could be the fan based on the symbol for it and also the switch.

The diagram may be more symbolic than actual since a lot of things are missing and possibly does not show the true wiring. The package of documentation that came with the unit may have a more detailed drawing or it could be on the back panel or on the inside of the back panel.

 

[FatDragon]

I was in Shanghai about 12 years ago on business. Looking out the hotel window the construction cranes were everywhere. Have fun! we'll figure this out when you get back.



Heat protector: Thermal protection for the compressor

Temperature controller: Thermostat, which has to be the metal box in the frig. The semi-rigid, non-insulated, silver-colored wire is a tube that goes to the freezer, which I would expect to be the freezer temp sensor.

Self-induction on/off / heater: This has to be the defrost heater on the evaporator coils. Not sure how the switch is controlled. usually it is controlled by a little motor that cycles the defroster, but the way its wired in the diagram does not make sense to me.

Turning plate heater: This heater is on all the time, which also does not make sense to me. based on the name possibly related to the ice maker.

Light: I originally thought this could be the fan based on the symbol for it and also the switch.

The diagram may be more symbolic than actual since a lot of things are missing and possibly does not show the true wiring. The package of documentation that came with the unit may have a more detailed drawing or it could be on the back panel or on the inside of the back panel.

Two more pics of the wiring up there. Got in late last night and was a bit shakier from the turbulence than my rational mind would like to admit, so I snapped these last night to deal with them this morning. I took a brief glance at the manual, but most of the diagrams I saw were about basic end-user operation of the fridge (i.e. don't lie it down while it's running, don't lick the electrical outlet to lubricate the plug connection, etc.). I'll look again and check the back of the fridge for diagrams tonight when I get home.

 

[PlexVector]

@FatDragon,
The yellow/Green wire is chassis ground, so we can ignore that for now. The other three connections: brown, black, & red are what I was expecting too see, but doesn't provide enough info yet. Next, you need to trace out where each wire/color is going.

1. Also, based on the picture of the frig in the previous link I'm assuming that is a fan in the back of the frig section just below the control panel--correct?

2. Is this a frost free Freezer?

3. What I see in the upper left section of the freezer is an ice maker, and it looks like three controls on the front of that same area. What is that?

4. The top half is the frig and bottom half is the freezer?

5. Are there any control knobs in the freezer section.

6. Can you see the end of the "silver semi rigid tube" in the freezer section?

7. What is that behind the thermostat? It looks like some type of insulation with foam surrounding the edge and clipped in by plastic tabs.

Based on the previous wiring diagram the following are my assumptions:
A. The "heat protector" is a bi-metallic switch attached to the case of the compressor.
B. The "turning plate heater" is always on to keep the water supply water outlet tube to the ice maker from freezing.
C. The "self-induction on/off" switch that controls a heater (defroster) is not in the metal box of the temp controller, but is a thermal switch attached to the evaporator coils and controls the heater next to the evaporator coils to defrost the coils. Since the temp controller shorts out the "defroster" so it can't be on if the compressor is on makes since but the "defroster" to be on, current has to flow through the compressor motor. this is weird. is it only enough current to run the heater and not run the motor or both are on at the same time, which does not make sense to me.
D. There is no fan or control of a fan in this diagram.

Be sure to unplug the unit during your investigation.

 

[FatDragon]

@FatDragon,
The yellow/Green wire is chassis ground, so we can ignore that for now. The other three connections: brown, black, & red are what I was expecting too see, but doesn't provide enough info yet. Next, you need to trace out where each wire/color is going.

1. Also, based on the picture of the frig in the previous link I'm assuming that is a fan in the back of the frig section just below the control panel--correct?

2. Is this a frost free Freezer?

3. What I see in the upper left section of the freezer is an ice maker, and it looks like three controls on the front of that same area. What is that?

4. The top half is the frig and bottom half is the freezer?

5. Are there any control knobs in the freezer section.

6. Can you see the end of the "silver semi rigid tube" in the freezer section?

7. What is that behind the thermostat? It looks like some type of insulation with foam surrounding the edge and clipped in by plastic tabs.

Based on the previous wiring diagram the following are my assumptions:
A. The "heat protector" is a bi-metallic switch attached to the case of the compressor.
B. The "turning plate heater" is always on to keep the water supply water outlet tube to the ice maker from freezing.
C. The "self-induction on/off" switch that controls a heater (defroster) is not in the metal box of the temp controller, but is a thermal switch attached to the evaporator coils and controls the heater next to the evaporator coils to defrost the coils. Since the temp controller shorts out the "defroster" so it can't be on if the compressor is on makes since but the "defroster" to be on, current has to flow through the compressor motor. this is weird. is it only enough current to run the heater and not run the motor or both are on at the same time, which does not make sense to me.
D. There is no fan or control of a fan in this diagram.

Be sure to unplug the unit during your investigation.

1 - Yes, there's a fan directly behind the control panel, in the center up the rear upper edge, while the control panel is top center of the upper chamber.

2 - I don't know the answer to this - my experience with another domestic freezer that seems to use a similar system (by appearance if not in reality) is that it produces very little frost unless you accidentally leave the door cracked, and then you're screwed.

3 - The "ice maker" is three suspended ice trays. Those knobs turn the trays over to dump the ice in the ice bin.

4 - Yes - upper chamber is fridge and lower is freezer.

5 - Nothing that I've seen.

6 - I haven't, but I keep accessing HBT from work, so looking for that will be on tonight's to-do list.

7 - That's more of a grate than insulation. I believe it's for airflow to the electronics up in the control box so nothing overheats up there. It faces back towards the fan but I'm not sure if that's significant.

To your assumptions - I don't know enough to respond to A or C, but I'm trying to wrap my head around them and learn the prerequisites to do so. B may or may not be relevant - there's no water supply (on any Chinese fridge I've ever seen, in fact), but if the ice cube trays are filled with condensate, that might explain the need for a heater. As for D, that is vexing - there is definitely a fan in the fridge chamber.

I haven't been able to track down a manual for the fridge. It's possible it got tossed with the packaging or that I stuffed it in some corner of my apartment. The operating instructions I was thinking of are on a sticker inside the fridge. The wiring diagram you found was on a sticker on the back of the fridge and may have some more information that will be of use. The rightmost element I couldn't identify was the compressor. There's other information on the left side I'll try to transcribe, sorry again for the potential poor translation of a couple items:

Freezing Star Level - (one white asterisk on a black background, three black on a white background)
Climate Type - SN/N/ST
Shock protection type - Level 1 Electronic appliance
Voltage - 220V
Frequency - 50 Hz
Amperage - 0.90A
Power Consumption - 0.67kW * h/24h
Refrigeration (something something - might be coolant but I'm not sure) installation volume - R600a, 98g
Foaming/Blowing agent - Cyclopentane (I'm seeing a few different translations, I assume they're all names for the same thing)
Total volume - 389L
Freezing volume - 121L
Refrigerating volume - 240L
Soft Freezing volume - 28L
Freezing Capacity - 12kg/24h
Weight - 102kg
Maximum light power - 1.5W

I guess maybe the next thing I need to do is plug it in and try to ascertain where the cooling in the frige compartment is coming from - whether the fan or possibly somewhere in the walls where there might be some lines running from the compressor (I hope not, since that would probably doom my intentions).

 

[PlexVector]

@FatDragon,
The extra info will help, and actually plugging it in and playing with the controls will help too. So, where does the water for the ice trays come from?

 

[FatDragon]

@FatDragon,
The extra info will help, and actually plugging it in and playing with the controls will help too. So, where does the water for the ice trays come from?

After a day of being plugged in and about three minutes to look at the fridge between coming home to pick up a sixer of homebrew for a friend and leaving to finally see The Force Awakens (just came out a few days ago in China), I observed that at the low setting it was turned to, the freezer was cold and the fridge was very slightly chilled. I've got it set to the lowest setting right now and want to run a few experiments - putting glasses of water in different parts of the fridge and seeing how cold they get at different settings, and also running the fridge at a low setting for a while, then seeing how it reacts when I turn the dial up.

I still don't know where the water for the ice trays comes from. My assumption is that it is probably added by the user if they want ice, but my secondary guess is that it's condensation that is routed into the trays. Probably not the latter, as that would presumably mean the ice was non-potable and the cube trays would overflow and create a big ice block in the bin if the user weren't diligent about twisting the knobs every once in a while.

 

[FatDragon]

I'm an idiot and have been wasting both of our time. I turned the fridge up to four on the dial (out of eight) overnight and when I got up this morning, there was frost on the back wall. There are definitely coolant coils in the wall of the fridge chamber. Should've done that weeks ago...

Time to get on the resale and begging for forgiveness train...

 

[rlmiller10]

I'm an idiot and have been wasting both of our time. I turned the fridge up to four on the dial (out of eight) overnight and when I got up this morning, there was frost on the back wall. There are definitely coolant coils in the wall of the fridge chamber. Should've done that weeks ago...

Time to get on the resale and begging for forgiveness train...

Sorry to hear that. I have been following this thread hoping that my original assessment was incorrect and you could make it work.

 

[PlexVector]

@FatDragon,
So sorry. I had high hopes we could salvage this frig for you, but I've never seen one quite this strange, and was getting stranger. I wish you luck!

 

[OdeCloner]

Why not just put a small ceramic heater in the fridge controlled by the STC? WalMart sells them for $10, and it'd be more than enough to raise the fridge temp to fermentation temp. Yes, you'd be fighting the normal operation of the fridge, but if you're in a pinch, there's no reason that shouldn't work.

You could probably disable the fan that pulls air into the fridge, and seal it up with aluminum tape. Just conduction from one side to the other would probably put the lowest temps at 40-50F, then use the heater to take it the rest of the way.

Just ideas.

 

[FatDragon]

@rlmiller10 @PlexVector

Thanks for the condolences. I should finally have a few minutes free (for seemingly the first time in a month) in the coming evenings, so I'm going to continue to prod around a bit and brainstorm for a few more days before I call it quits, but the dream is probably over. Likely best case scenario at this point is that I resell it with no hitches and get back 80%+ of what I paid (and don't have to give up half a day renting a van to deliver it to the new owner myself).

Why not just put a small ceramic heater in the fridge controlled by the STC? WalMart sells them for $10, and it'd be more than enough to raise the fridge temp to fermentation temp. Yes, you'd be fighting the normal operation of the fridge, but if you're in a pinch, there's no reason that shouldn't work.

You could probably disable the fan that pulls air into the fridge, and seal it up with aluminum tape. Just conduction from one side to the other would probably put the lowest temps at 40-50F, then use the heater to take it the rest of the way.

Just ideas.

I've thought of using a heater to fight the normal operation of the fridge, but I'm not sure if it would really be worth it - not only would the chamber likely experience constant temperature swings, but it would waste a ton of electricity.

For the latter, I must admit that I might be wrong about the vent in the back containing a fan, since neither PlexVector nor I can find a fan on the documentation. There is a vent that looks like it could contain a fan that would draw cold air from the freezer up to the fridge (and that seems like a logical system and probably cheaper and more temperature-accurate than running compressor coils up into the fridge itself), but since it seems that the cooling in the fridge comes from the coils in the fridge compartment, and since the diagram makes no mention of a fan, I now suspect that it's just some kind of vent and doesn't contain a fan at all.

Not yet giving up, but not holding out hope either. If all goes well, I'll have this settled one way or the other (rigged up or sold) before the Chinese New Year in a couple weeks.

 

[FatDragon]

Talking to myself at this point, I'm sure, but there definitely is a fan in there. I thought I was wrong when no air came out the front, but it actually hovers a bit in front of the rear wall and the fan blows air toward the rear wall, presumably circulating air off that wall where the coils are located.

 

[PlexVector]

Talking to myself at this point, I'm sure, but there definitely is a fan in there. I thought I was wrong when no air came out the front, but it actually hovers a bit in front of the rear wall and the fan blows air toward the rear wall, presumably circulating air off that wall where the coils are located.

That would be the fan for the compressor/condenser coils, which is different that the fan I would expect inside the fridge. Based on your description and the electrical diagram I'm at a loss for any ideas. If I lived an hour away I'd drive there and help. I don't like to give up so easy.

Looks like my notifications are not working reliably again. Sorry for the late reply.

@PlexVector