DIY temp controller build

rycov said:

ok. so what i want to do is connect the bottom two, that are turned perpendicular to the others, to the thermostat and transformer, then connect the wires from the wall to the outlet through two of the other poles? does it matter which ones i use? also it looks kinda little to be running 120 volts through.

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Yes, the two turned perpendicular go to the coil. The two adjacent to it are the poles, and the next two are the throws.

Each pole will have one throw it is normally in contact with. You want to connect to the opposite one. I'm not sure which one that is, but you could test it pretty easily.

It should not matter which pole you use.

As for the size of the relay, as long as its rated for the voltage and amperage you are running across it, you should be OK.

its rated for the amps and voltage i need. does this look right?

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at my work computer. wont let me upload the picture. i'll ask again when i get home. thanks man

this looks very interesting....

im hoping someone can help with a question:

Is this something that could be put in charge of a fermentation chamber for maintaining ale fermentation temps?

Im looking at the son of a fermentation chiller instead of a fridge for my cell design, and Im also thinking of adding a heater element so the chamber can go both ways (my garage is where im planning to operate this rig.

anyone else doing this?

love the DIY stuff... thanks for sharing.

That is pretty much how I plan on using mine, although I will be using a refrigerator. I have seen some people who have implemented it primarily for heating and have just hooked an internal fan up for the cooling to circulate the air that has been cooled by the ice throughout the chamber and then used something like one of those reptile infrared heaters for the heating aspect.

The general principal remains the same - you need a way to trigger your cooling and heating actions. Only real difference, from what you are looking to do, is likely that you will only need AC voltage to drive whatever heating element you plan on using. If you are going to use a fan for cooling circulation, you can either get a 120V fan to run off of line voltage, or provide a lower voltage source to power a lower voltage fan - i.e. a 12V DC fan powered by another power source, etc.

Overall, the design of these temperature controllers provides a great bit of versatility. You can even use them for other non-brewing applications. Greenhouse temperature control would be a good example of that.

please let me know if this looks right

View attachment relay.bmp

rycov said:

please let me know if this looks right

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I don't think so. You probably will connect the power supply through two terminals which are in the same column.

Not all relays are the exact same, but thats the typical configuration.

You can always test, either with a continuity tester, or some low voltage signal. (Before I got a digital multimeter, I tested mine by connecting a speaker cable across it and knew it was working when the sound would turn on and off)

The lower one is probably the pole, then there is a NC throw and a NO throw. (normally open and normally closed). Connect your power supply across the pole and the NO terminal.

Hope this works for you.

ok. i think i see what your saying. sorry for all the questions. i really have know idea what i'm doing. but i can test it with something else, like a speaker, or a small light bulb or something?

rycov said:

ok. i think i see what your saying. sorry for all the questions. i really have know idea what i'm doing. but i can test it with something else, like a speaker, or a small light bulb or something?

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Yes, and for the love of God be careful.

It may not be 240V, but still enough to hurt and/or kill you, or burn your house down.

Use appropriate sized wire, and insulate well (especially at relay terminals). I would recommend these:

Besides that, Good luck!

i will be very careful. i get what all of the parts are doing, i'm just not sure about these relays. all they had at radio shack was the coils. they didn't have any of the solid state ones that were in some of the earlier posts. i'll be sure to check and double check everything. thanks for the recommendation, i'll see if i can find some of those.

if the relay is rated for 12 v can i run it off a 5 v phone charger?

This question is for those of you that have built one of these systems.

I am planning on using one of these to convert a freezer to a kegerator and was wondering what the sensitivity is on the unit. Will it be constantly turning my compressor on and off or does it not kick on until it breaks a certain range (like the johnson controllers)?

Thanks,
Dave

i think there is a build in delay on the thermostat that i used. it might turn on the freezer more than something with lots of set points, but i bet it won't be that much more.

the thermostat i bought has settings that i can change to have 1 3 or5 degree "dead zone". i would think all home thermostats would have this, or else it would be cutting your AC and heater off and on all day.

It's working nicely at controlling this fridge, can't wait to get it to the real one. I used an automotive relay instead of the SSR.

Could this be used to run a Water Heating element??

Technically, if the relay is built to handle that voltage/amperage, yes. The temperature-sensitive device is only turning the relay on or off.

I'm using this idea for my fermentation chamber. I already have modified thermostat from my old SOF chiller that I can use. Pretty much all I need to do is add a SSR.

stamandster said:

Could this be used to run a Water Heating element??

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Yes, but I haven't seen anyone do this before. Probably because the temperature reading may not be accurate enough. Have you found anyone who has done it?

I am having my first brew day today and I built one of these yesterday in order to better control my temperature (I keep my house between 76 and 78 which is bad for fermentation). I ordered a SSR from eBay and I am temporarily using an automotive relay from Radio Shack. Other than the Hunter Thermostat seems to be about 2.5 degrees off I am quite happy and I have not set the house on fire. American Wheat (all-grain) is mashing right now at the target temp.

Just an fyi the ssr relays won't switch without a load of some sort.
So just powering up the low voltage control side and checking for continuity may leave you to believe they aren't working.

Just wanted to post this so people know the temperature range on these Hunter thermostats. For the digital thermostats, the settable temperatures, according to their websites FAQ, is from 40F to 95F.