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Thermostat for Fermentation temp control

I was wondering what thermostat is recommended for temp control during fermentation. I have a standard size chest freezer and would prefer the “plug and play” style since I am not very handy at wiring.

I would look at Johnson temp controllers. NB sells them. Looks like they are all digital now but the old dial one I have works fine. +/- 2° temp swing so if you set it to say 65° it will kick on the fridge or freezer at 67 then leave it on down to 63.

If they still work the same way, you simply unplug the fridge, then plug it into the cord/plug from the controller then place the controllers temp probe inside.

Someone correct me if that is not how they still operate.

Exactly right. Bought my second one recently for my kegerator and it was the A421 from Johnson Controls/I have the 419 set up for my fermentation fridge(fermigerator :grin: ) already. The new one is even simpler to set up. Plug and play it is.

I took a leap and put the probe into jar with water. No problems, AND, the freeze-mentor (fermigerator) doesn’t cycle as much. Sneezles61

I use this as my controller and it works really well.

There’s another cheaper version that works up to 10 A. I just got the 15 A version in case I ever need it for another application.

I use the Ranco version. I got mine unwired off amazon for $48.00. I then bought a 25’ extension cord for wiring since I wanted the controller far away from the closest outlet. I’m very limited in electronics and wiring and I did mine in about 10mins. Got what I wanted… a quality controller with a long cord (most come with short cords) at a great price.

Be warned that with a Johnson controller you have to manually flip between cooling and heating, if need be.

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I’d recommend a 15A controller. 10 Amps should be good, but is a bit close for a freezer. With 15A you got no worries if you decide to get a bigger freezer…

Wiring a controller is actually not all that hard, but the confusing terms and symbols make electrical stuff seem harder to learn than say, plumbing. Even though plumbing is actually harder to do right, (IMO)

Still, if you’re afraid of wiring, then you’re right to look to a pre-built controller. US 120V wiring can kill the careless and unknowledgable. Better safe than sorry, or dead.

…On the other hand…
if you can figure out what fraternity the local college’s electrical engineers are in, they might accept beer in payment for helping you wire a controller. Any student electrician could too. Either way, just make sure they’re 21 before offering beer in payment.

I use a inkbird itc-308 I got from amazon 38 dollars plug and play. Sorry just looked on amazon the controller is 35 dollars.

I’ve heard of them. For $35 that looks almost too good to be true. Yea Amazon.

I pulled the manual off the Internet, and other than the 10A limit, and some confusing engrish wording, it seems to have everything that’s really needed. I presumed at that price it wouldn’t have short cycle protection, but it does! They call it Compressor Delay, which somehow get abbreviated as PT… so all the boxes seem to get checked.

Just compare the specs on the freezer. A pretty new chest freezer should be drawing 10A or lower. They can draw a bit more at start up though.

I have a chest freezer that’s about two years old, and I haven’t had any problems. I have the controller set for plus or minus 2 deg of 38 deg.

I have mine anywhere from 65 on down to 30. it all depends what your wanting to do… Sneezles61

I use mine for my kegs and bottles.

Thanks for all of the advice. I think I have a good handle on the thermostat now.

Any advice on ways to heat up my chamber during the second phase of fermentation?

If you ferment in your house, as I do, set it for 70* and open the lid for a few days. I’m still strong enough to pull mine out of the freeze-mentor and set on a tall table to finish its job. Then rack off its lees into a keg for cold crashing… Sneezles61

If you’re concerned about the amperage draw exceeding the capacity of your controller/thermostat, consider using the thermostat to activate a high-amperage relay. [link to relay from]

Salvage a three-wire cord from an appliance that’s ready to be tossed. Connect the black and white wires to the square, blade-like terminals - one wire on each side. Assuming a three-wire cord, the green wire goes to the base of the relay, held down with a screw into the base of whatever you use to enclose the relay.

Cut a heavy 120V extension cord in half. Connect the half with the male plug - the part that plugs into the wall - the black and white wires go to the heavy, screw-down connectors on one end of the relay. If there’s a green (ground) wire, screw it down to the base using the same screw you used before (this becomes the input). The output connects similarly to the other end using the female end of the halved extension cord, including the “green wire drill”.

Plug the freezer, refrigerator (or other thing that makes stuff get colder) into the outlet. If your controller can be switched to Heat mode, it can also control a heater.

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