Temperature controller for a fermentation chamber

[Lemontato]

EDIT: The STC-1000 is rated for connections at 5A, a fridge is 15A, won't the STC-1000 connections fail after a while? Also, where should I put the probe? In my wort?

Hello again,

After a few advices about better controlling my fermentation temperatures, I started looking around for a fridge and a temperature controller.

I don't quite understand how temperature controllers work, could someone explain it better to me? As I understand it right now, it is just something that plugs between your fridge and the power outlet, and is pretty much a on/off of the fridge depending on the sensor readings of the controller.

Since the ambient temperature where the fridge is will always be higher than my target (22-24C ambient temp), I would only need a single stage controller? A cooling one or heating one? Like I said I don't understand how they work so I don't know which type I would need.

Considering a max budget of 100$, which model should I look into?

Thanks!

 

[HumulusHead]

If the ambient temperature is always WARMER then what you want to ferment at, then you will be just fine with a single stage controller. You would only need to hook a fridge up to the controller then.

I would reccomend getting a dual stage controller though just for future use, they are pretty much the same cost as a single stage.

You can pick up an STC-1000 on Amazon for like $18 shipped.

There are alot of threads on here on how to make a controller for real cheap, but here is the quick and dirty:

1) you have a temp controller that is wired to an outlet (does not need to be in the wall, just a normal 110v outlet)
2) plug the temp controller into the wall.
3) the temp controller turns the power to your external outlet on/off based on what temp you set the temp controller for
4) the fridge is plugged into the temp controller external outlet and will be turned on/off as the temp controller turns on off

probably a terrible description, but that is the gist

You can pick up a mini fridge on craigslist for aroun $50. With a little modification (removing the inside shelves, or whatever it takes) you can easily fit a 6 gallon carboy or a 6 gallon bucket. Just make sure to get one that will fit whatever vessel you use.

The temp controller, like i said, is about $18 shipped. Will need to spend prob another $20 to get it wired up. You will need an extension cord (heavy duty, 10 LF is plenty), an outlet, some sort of box for the outlet (I just use the normal blue single gang wall boxes), and some wire nuts.

You could also purchase a temp controller that is pre wired. They have them online from like northern brewer.

 

[HumulusHead]

It sounds like your general idea of how the temp controller works is right on btw

 

[Lemontato]

Great! Thanks for the help

 

[danath34]

EDIT: The STC-1000 is rated for connections at 5A, a fridge is 15A, won't the STC-1000 connections fail after a while? Also, where should I put the probe? In my wort?

double check the amperage on the fridge. My fridge is 2A running, but its a small one. If you were using a bigger chest freezer type thing, your amps would probably be around 7 (this is a guess and generalization - definitely check before wiring it up).

The STC-1000 is rated for 10A, and on top of that, people have taken them apart and reported that the relays are actually either 12A or 15A relays (though I cant remember which). Now you are going to have a small spike of current higher than your running current when the motor first kicks on, but it is for a short amount of time. As long as the motor is good, it should be a second or two or less.

I actually went back and forth on this exact same issue when I was building mine. I was looking around at 20A relays to use to do the actual switching, but in the end, it would have been way overkill, and I wired it up as-is.

The bottom line is your wall outlets are typically only rated for 15A anyway. As long as you wire your STC-1000 up to something you can plug directly into the wall, you're just fine.

 

[Smellyglove]

15A for a fridge sounds like a lot. Thats 1800W @ 120V, are your sure about this amperage? I have a "normal" sized fridge which pulls less than 200W @ 230V.

Like Danath34 over here is saying. STC-1000 is rated for 10A.

 

[Lemontato]

Alright, thanks for the info! Went and bought a STC-1000.

 

[GotDrunkThenLost]

This is the video I emulated when I built my temp controlled switches a few weeks ago.

[ame]https://www.youtube.com/watch?v=SrdOpk10MkE[/ame]

 

[freisste]

Just to point this out: the fridge or freezer will run at relatively low amps, but you have to be really careful with startup amps. You will burn up your motor way faster if you do not have high enough amperage for startup. It will appear to be working correctly, it just won't work correctly nearly as long as it should. This is why it is code for refrigerators to have a dedicated circuit. YMMV.

P.S. Thanks for the quick write up. I ordered my stc 1000 today!

 

[danath34]

Just to point this out: the fridge or freezer will run at relatively low amps, but you have to be really careful with startup amps. You will burn up your motor way faster if you do not have high enough amperage for startup. It will appear to be working correctly, it just won't work correctly nearly as long as it should. This is why it is code for refrigerators to have a dedicated circuit. YMMV.

P.S. Thanks for the quick write up. I ordered my stc 1000 today!

this is absolutely correct.

However, as far as I know, from conversations with a couple electricians (but I still may be wrong, so correct me if I am) if the startup amperage exceeds 10A, the issue isn't that the STC won't put out the required amperage, it will. The issue is if that amperage exceeds the rating of the relays for long enough, the relay will burn, which in the case of the normally open relays, they will get stuck in the closed position, and the fridge won't turn off until its own thermostat kicks it off. The STC is just a couple of relays with a little bit of logic. It's either full power right from the wall, or none. And the little power draw the STC itself uses for the display and logic shouldn't be enough to interfere with the fridge motor.

 

[freisste]

this is absolutely correct.



However, as far as I know, from conversations with a couple electricians (but I still may be wrong, so correct me if I am) if the startup amperage exceeds 10A, the issue isn't that the STC won't put out the required amperage, it will. The issue is if that amperage exceeds the rating of the relays for long enough, the relay will burn, which in the case of the normally open relays, they will get stuck in the closed position, and the fridge won't turn off until its own thermostat kicks it off. The STC is just a couple of relays with a little bit of logic. It's either full power right from the wall, or none. And the little power draw the STC itself uses for the display and logic shouldn't be enough to interfere with the fridge motor.

I absolutely agree with your last sentence. For the record, I'm no pro - I know just enough to make me dangerous. And thanks for the information. I just looked at my chest freezer owner's manual and read that it must be plugged into a 15A outlet. I came here to ask if the stc-1000 limited amperage. From my understanding of relays, I don't know how that would be possible, but again I'm no pro.

Does anyone know what the relays are rated to handle?

 

[Smellyglove]

Does anyone know what the relays are rated to handle?

Wouldn't that be the 10A which the STC is rated for?

 

[HumulusHead]

Someone else was saying that the relays inside the stc are actually rated higher than the stc itself


Sent from myPhone

 

[freisste]

I did some more reading and found a post by IslandLizard where he stated that he took a controller apart and the relays were 10A at 220V or 15A at 110V.

My fears have been alleviated.

Post #273:

https://www.homebrewtalk.com/f51/stc-1000-ebay-temperature-controller-build-330427/index28.html

 

[danath34]

there ya go. I knew I read that somewhere but I was too lazy to look it up myself. that's the post i read though.

and no, the STC will not limit amperage output. sounds like it's really good up to 15A, and in reality it will go higher than that, but then you run the risk of burning a relay. but you shouldn't pull more than 15A out of a 110v wall socket anyway.

 

[FuzzeWuzze]

this is absolutely correct.

However, as far as I know, from conversations with a couple electricians (but I still may be wrong, so correct me if I am) if the startup amperage exceeds 10A, the issue isn't that the STC won't put out the required amperage, it will. The issue is if that amperage exceeds the rating of the relays for long enough, the relay will burn, which in the case of the normally open relays, they will get stuck in the closed position, and the fridge won't turn off until its own thermostat kicks it off. The STC is just a couple of relays with a little bit of logic. It's either full power right from the wall, or none. And the little power draw the STC itself uses for the display and logic shouldn't be enough to interfere with the fridge motor.

The relays are rated for 15A as far as i know, if your fridge is pulling more than 15 amps its going to trip your circuit breaker anyways and kill all power to the entire thing.

Unless your using some giant commercial freezer you'll be fine, ive never heard of anyone tripping a circuit with a single chest freezer on the circuit.

 

[tooladverser]

So good to see this thread. What only knew is how to test the temperature but don't know how to control the temperature.