Using a Johnson Digital Temp Controller and a Chest Freezer...questions

Temps are extremely important, you don't want large swings while fermenting...and you want to stay in your yeasts sweet spot. Higher temperatures can cause off-flavors...though usually not described as plastic-y.

Maybe I'm missing something, but your Johnson controller should be able to bring your fridge to any temperature below room temp. If you're just measuring the ambient air inside the fridge...it's not going to give you an accurate representation of the temp of your beer.

1. Yes, that could be playing a role.
2. Yes, I use a Johnson control A419 with chest freezer, and have great results.

 

What most people do, including myself, is to attach the temp probe to the carboy. You do this with tape, the you wrap the temp probe with an insulation material, like bubble wrap for instance, so it isolates the probe from ambient. The ambient air in the fridge doesn't matter, you want to control the temp of the fermenting wort.

The method of attaching the probe to the carboy isn't perfect...the probe will still be subject to ambient temperature...although it will have less impact on the reading. So, when your beer is at the height of fermenting and your controller is really making your fridge/chest freezer work...the temperature displayed on the controller will probably be 3 degrees off or so. However, your 5 gallons of wort will be at the proper temp.

I have used it solely for ales so far, though I have some lagers planned.

 

I don't understand how your fridge is not able to warm to more than 55F. As JohnSnow said, it ought to be able to warm to whatever your temperature is.

Are you setting your controller correctly? There are two different settings on most temp controllers, one in which the power kicks in when the probe senses the temperature is above a certain setting, and another in which the power kicks in when it is below that setting. If you are hooking the temp controller to you fridge's cooling system, you want to set it to kick in when the temp gets above your setting. If you do that, the cooler ought to be able to maintain ale fermentation temps easily.

And yes, fermentation temp makes a huge difference for most beer styles. Whether that's responsible for the off flavor you mention, I don't know, but all things being equal controlled temperature will result in much improved beer.

 

One other thing to mention is that even after the Johnson Controler brings the temperature down inside the fridge to what you've set, the fridge/freezer will continue to cool beyond that point. The cooling lines inside the fridge/freezer don't stop cooling immediately after they've been turned off...they slowly stop cooling. So, this will cause the ambient air inside the fridge/freezer to be cooler than you've set. This has no impact on the 5 gallons of liquid you have fermenting, however. This is why it's important to isolate your temp probe from ambient.

Apologies, if I've explained something you already knew.

 

If your Johnson controller will not control the temp of your mini-fridge it will not do any better with a chest freezer. I would put all my efforts into figuring this out first.

Are you positive you are programming the differential correctly? There are a couple of good youtube videos that show this. I use another brand, but in the cool mode the differential is added to the set point to create a high-side temp to cut on the unit. I.E, if you want to hold 65 you set 60 with a 10 differential.

As Johnsnow says, air temp is not important. To test your unit put your primary with 5 gallons of water in your mini-fridge and give it 24 hours to stabilize. Use a floating thermometer and see where your water ends up. You should be able to absolutely nail the temp.

How do you get an 'accurate representation' of the temp of the beer, without a thermowell?

Place a 750 bottle of water in your mini-fridge with a thermometer. After it stabilizes, the temp of the water will approximate the temp of your wort before fermentation takes place. Actually your wort temp is even more stable because of the larger quantity.

My set-up is a little different because my temps are PDH. I leave the probe exposed in the air and set an 8 - 10 degree differential. This is to minimize the cycling of the compressor. If I want to ferment at 66, I set the controller to hold a temp about 5 degrees below this number (because of heat from fermentation). So I want the thermometer in the water bottle to read 61, I set 57 with a diff of 8. That will give me a wort temp of very near 66. I use an inexpensive aquarium temp probe (Amazon, $3) that I place on the carboy behind bubble wrap. This gives me a reading close to the actual wort temp and I can see it without opening the door.

A couple of caveats: It takes a long time to change the temp of liquid a few degrees, when testing let it sit overnight. In my technique above I raise the controller temp slowly as the fermentation slows down. Don't be alarmed with a 8 - 10 differential . . . the thermometer in the water bottle never changes. Each controller/fridge may be slightly quirky, it will take a few test runs to dial in your settings.

 

I use a chest freezer with a johnson controller..

Works just fine at ale temps, lager temps, and hot as fuck temps.

I tape it to my carboy during active fermentation and have the probed wrapped in a semi closed cell foam. Keeps my ales at 62 during fermentation, and then I put the probe in a cup of water I have in the freezer when I want to hold a steady temp for a longer duration in the freezer, say... when I cold crash or lager.

If I'm fermenting two batches, generally I try and use yeast with a similar temp profile, so I can just put it on one that would be hotter and more active.. Such as.. US05 and US04.. 04 will get hotter and be a bit more violent, so I keep the probe there, and it keeps the temps right in check during active fermentation of the US05 as well.

Temp control is paramount to making good beer. Period, end of story. Yeast handling, which goes with temp control is the engine of your beer.

 

Dark fruit off flavor. Hmm. I wonder if a tasting would help. I'm not bidding for a sample, but you should take some of these beers to someone who knows his crap. Maybe a LHBS or a local microbrewer. I'm leaning away from temperature being the issue, but I'm still looking at an answer being PROCESS oriented. Are you still an extract brewer? If so, I wonder if you're getting scorching on the bottom of your kettle.

 

As for temperature, you shouldn't be getting up into the mid 70s unless you're doing a saison. As for the controller, it should be able to keep a pretty steady temp from 32F to what? boiling? I wonder if you're able to do hot and cold and you need to switch over. Otherwise, look through the manual and try reconfiguring it. Practice with a 5 gal batch of water. You'll need thermal mass in the fridge to help regulate your readings. See if you can dial it in within 1 or 2F and post back if you can't.

 

i am about to get one of these:
https://www.cool-brewing.com/BuyNow/tabid/82/ProdID/1/Default.aspx

you just throw your fermenter in there with a few frozen 2 liters and there ya go.

 

I had a similar problem last year with some british ales I made. The british ale yeast really doesn't like anything warmer than 70. I would say your temps are the problem.

 

Just wanted to chime in and say that if you are ok with shopping on craiglist, there are typically some really good deals on chest freezers...like this.

I got my 17.5 cu. ft. off of craiglist and am very pleased with it.

 

It sounds like you are poorly describing some of the flavors from English strains when fermented warm. Those strains don't do well in the mid-70s and above (you might be getting some fusels) and a lot of people do not like the yeast flavors of English strains when fermented even in the upper 60s. They have very bready and tangy flavors, not like the very neutral American yeast strains most of us are used to.

This might be a dumb question, but are you plugging in the fridge to the controller? If you have the A419 (or the knob version) then you plug the controller into the outlet and then plug the fridge into the other cord coming from the controller that has a female plug. Otherwise the controller can't turn the fridge off. Again, you probably have it plugged in right but it never hurts to eliminate the obvious.

Other people have made good suggestions about checking your settings. One other thing to check is the jumper placement. The default setting from the factory is for the controller to turn on the fridge when the temperature is above the set temperature and cut it off when it reaches the differential below your set temperature. It's possible the jumpers were accidentally installed to run the fridge when the temperature is below the set temperature. That's an easy check. Just unplug the controller, unscrew the four screws on the faceplate and remove the faceplate. The jumpers are very prominent right behind where the screen would be if the faceplate was still there. The jumpers should be set for both off with both jumpers on the prong on the left. The right prong on each jumper station should be exposed. If that is not the setting then you can use needle nose pliers to pull the jumpers and set them correctly. The manual also explains that.