STC1000 Issue

[Trevorrow]

Sorry if a repost, I'm sure this may have been covered in one of the thousands of threads about temp controllers.

Earlier this year I was surprised to find my kegs frozen solid in my DIY keezer. I chalked this up to a faulty STC1000 I had in place. It had worked fine for a few months prior. I replaced it with another unit I had laying around that worked great until the same issue occurred this week. Is there an explanation as to why my STC1000s are failing? Should I buy an inkbird controller?

 

[IslandLizard]

Chances are the little relay contacts have fused/welded together. So they stay in ON mode forever.

The inrush current of the compressor can far exceed the specs of the relay contacts, causing them to weld together eventually. You could take that load off those relays by letting them activate an SSR (or a contactor), which in turn will close the main power circuit. SSRs are fairly cheap (~5-7 on Ebay, China made). Get at least a 20 amp one, about double of what you'd need, for all security. Their specs aren't all that reliable either, lots of aftermarket stuff isn't.

You can check the little relays with a multimeter, if you find continuity even when the unit is powered off, the relay is stuck.

You can replace the relay if you're handy with a soldering iron. I'm not 100% sure if the STC can drive an SSR directly, omitting the micro relay all together.

 

[Trevorrow]

That makes sense, thanks. It looks like the inkbird 308 also has a 10A relay. Before redoing this and adding in an SSR or RIB, are there any temp controllers on the market that can handle greater than 10 amps, to be safe? It looks like the Johnson unit can handle 16A.

 

[IslandLizard]

That makes sense, thanks. It looks like the inkbird 308 also has a 10A relay. Before redoing this and adding in an SSR or RIB, are there any temp controllers on the market that can handle greater than 10 amps, to be safe? It looks like the Johnson unit can handle 16A.

The plug and play Inkbirds are based on the STC-1000 with different firmware. They also make a heavier, 12A or 15A unit, IIRC. Probably not a big difference internally, except for a larger load relay, which may or may not fix your problem ultimately.

There is a long thread on the STC-1000 and a few on firmware modifications. Maybe a fix to your relay issue has been covered there, or post your question in the main thread, and see what rolls out. You probably can find a better relay, but chances are it won't fit the PCB.

I wonder if it's just a fluke to have 2 of them go belly up or something with your keezer that fries them. 1000s of people, not just brewers, use these units, with very little problems. I use 2 of them myself, been going well for years.

The Johnson A419? It can switch up to 2000W apparently. It may be using a better, beefier relay. But it only does cooling, single relay, which is fine for keezer use. Not sure if it has a built-in compressor delay, which may not be an issue for you. Lots of people use them too. For that price they should do a lot more...

 

[brew703]

I use the Johnson A419. Have been for three years with no issues. It does have a compressor delay, which is adjustable.
The only issue i have is the temp swings. Usually 2-3 degrees. I have the set temp at 60 and it doesn't shut off until 57. I've tried fixing this but either it cant be fixed or i just don't know what I am doing. Could be either.

I also have an Inkbird ITC1000. Had it for three years (before I bought the A419). Just don't use it because when the cooling side kicks off it wants to turn on the heating side. I don't have anything plugged into the heat side but there is still a small amount of juice going through it so i elected not to use that controller. Inkbird has various other controllers on Amazon but haven't tried any.

Wish Inkbird made a controller that would shut off completely when the cooling side turns off. Maybe he does- just haven't researched it much.

 

[Trevorrow]

The plug and play Inkbirds are based on the STC-1000 with different firmware. They also make a heavier, 12A or 15A unit, IIRC. Probably not a big difference internally, except for a larger load relay, which may or may not fix your problem ultimately.

There is a long thread on the STC-1000 and a few on firmware modifications. Maybe a fix to your relay issue has been covered there, or post your question in the main thread, and see what rolls out. You probably can find a better relay, but chances are it won't fit the PCB.

I wonder if it's just a fluke to have 2 of them go belly up or something with your keezer that fries them. 1000s of people, not just brewers, use these units, with very little problems. I use 2 of them myself, been going well for years.

The Johnson A419? It can switch up to 2000W apparently. It may be using a better, beefier relay. But it only does cooling, single relay, which is fine for keezer use. Not sure if it has a built-in compressor delay, which may not be an issue for you. Lots of people use them too. For that price they should do a lot more...

Thanks, I'll take a look in the other thread. It's an insignia 7 cu ft unit i picked up a little over a year ago, I can't imagine it would be causing the issues. I'll look into one of the 15A STCs and see how that fairs. I would prefer to not spend upwards of $60 for the Johnson.

 

[IslandLizard]

I also have an Inkbird ITC1000. Had it for three years (before I bought the A419). Just don't use it because when the cooling side kicks off it wants to turn on the heating side. I don't have anything plugged into the heat side but there is still a small amount of juice going through it so i elected not to use that controller. Inkbird has various other controllers on Amazon but haven't tried any.

Wish Inkbird made a controller that would shut off completely when the cooling side turns off. Maybe he does- just haven't researched it much.

I'm not familiar with the ITC-1000, but shouldn't or can't you set the heating target temp a few degrees BELOW the cooling target temp to prevent that? That setting will tell the ITC to start heating when the temps drop below xx°F/°C.

I can see if your heating target temp is set at or ABOVE the cooling target temp, you'll get exactly what you're experiencing.

There are 2 relays inside, one for each mode, cooling and heating. They work independently, but never at the same time. It's either cooling OR heating.

IMO, there cannot be a small amount of juice flowing through the heating circuit if it's not calling for heating.

It may also have to do where your probe is located.

 

[IslandLizard]

Thanks, I'll take a look in the other thread. It's an insignia 7 cu ft unit i picked up a little over a year ago, I can't imagine it would be causing the issues. I'll look into one of the 15A STCs and see how that fairs. I would prefer to not spend upwards of $60 for the Johnson.

If this "Johnson" is the same multi billion dollar, multinational company that "builds" controllers, ACs, heat pumps, etc. under various brand names (e.g., York, Coleman), I'm not surprised of the price point. Neither if those controllers are actually manufactured in China or assembled somewhere from Chinese parts.

That's not a very large fridge/compressor. I really wonder what causes it. There have been very few problems reported with these units. If you're handy solder in a new relay (eBay/China). If you're not using the heating side, "borrow" that relay.

You could buy one of those temperature gauges/sensors with an alarm as a safeguard. When the temps drop below say 40F it will scream. Some will even send you an email.

I think this is the main STC-1000 thread. So also search under "aquarium" controllers and such.

I hope you find the information there, it's a long thread, or just ask and see if someone can point you in the right direction.

Also, do searches in Google Chrome like this, it only returns links from the indicated site (beats the search engine in HBT, which is a joke):

site:homebrewtalk.com your_query​

If you have your # of returns set to 100 instead of the silly default of 10, you'll be paging a lot less.

BTW, here's a post where the relay on his model shows 15A at 110V.

 

[brew703]

I'm not familiar with the ITC-1000, but shouldn't or can't you set the heating target temp a few degrees BELOW the cooling target temp to prevent that? That setting will tell the ITC to start heating when the temps drop below xx°F/°C.

I can see if your heating target temp is set at or ABOVE the cooling target temp, you'll get exactly what you're experiencing.

There are 2 relays inside, one for each mode, cooling and heating. They work independently, but never at the same time. It's either cooling OR heating.

IMO, there cannot be a small amount of juice flowing through the heating circuit if it's not calling for heating.

It may also have to do where your probe is located.

I'll have to check that. I never had it in use due to that issue. If i recall i believe there were like 2 amps going through the heating side. Not alot but still a concern for me when no one is home during the day.
Thanks for the info. Never really thought of that.
Also, i think i emailed Inkbird about this issue. I cant remember exactly what he said but the reply didnt satisfy my needs to i just went with the Johnson Controls.

 

[IslandLizard]

I'll have to check that. I never had it in use due to that issue. If i recall i believe there were like 2 amps going through the heating side. Not alot but still a concern for me when no one is home during the day.
Thanks for the info. Never really thought of that.
Also, i think i emailed Inkbird about this issue. I cant remember exactly what he said but the reply didnt satisfy my needs to i just went with the Johnson Controls.

Well 2A means there's 220W being used... I guess the heater is on.

 

[brew703]

Well 2A means there's 220W being used... I guess the heater is on.

I'm not 100% certain it was 2A. That was a while ago. I do recall we checked it and there was some juice.
I'll try your suggestion when i get home and see it that works.