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Temp control device

Yeast & Fermentation
#1

I’ve had a freezer out back that I only use for overflow when we had too many things in our refrigerator freezer. After struggling for years here in the South to keep my brews cool enough with swamp coolers and ice, I finally got smart and bought a temperature controller for the freezer. I wish I would have just spent the $60 earlier, but hindsight’s 20/20.

I recently heard in a podcast that the fermometers aren’t very accurate because of the insulation between the beer and the fermometer, so my question is how do you guys control your temperature? I’ve read that you can take put the temp gauge in a glass of water to more accurately control the temperature of the fermenting wort.

Also, I’m fermenting safale-S04 which has a suggested range of 64-75 degrees. What temp should I set the control? I have it set at 62 right now, and I’ll probably move it up as the temp of the wort drops–I pitched at 84 degrees because I couldn’t get the wort down much cooler with my wort chiller. I was thinking about keeping the range in the middle (67-68 deg), so I could for once get a fairly clean fermentation.

I know that towards the end of the fermentation I should push the temp up a little bit, but I wanted to see how some of you who have temp controllers manage your temp and see if you have any advice.

#2

The reason for putting the probe in water is to simulate the mass of the beer. If you just stick the probe in the open air, as soon as the unit kicks on, it will sense cooling and be satisified and kick off. Your wort will take forever to get to the proper temps. By putting it in water, the water must adjust to the set temp and that more accurately represents your wort temps.

For Ales, I set mine at about 60-61 degrees at first and after a week, move it up a bit.

#3

I use this in a small chest freezer:

http://www.northernbrewer.com/shop/brew ... oller.html

I am also pretty fortunate as my basement is high 50’s to mid 60’s year round. Ales I try to keep in the low 60’s.

When I use the freezer and set the temp, I tape the probe to the side of my bucket with some sort of padding or foam over it - so it is more closely reading the temp. of the fermenting beer and not the temp of the air.

#4

I put the probe against the fermenter and wrap it with bubble wrap

#5

I do this but usually with a few layers of paper towel instead of bubble wrap.

I usually assume that my beer is about a degree warmer than what my probe says if it’s fermenting vigorously, but there’s no science behind this assumption.

#6

+1
the best is to put the sensor into the fermenting wort, but you need a thermowell because the sensors aren’t water proof.
2nd best is to tape it to the side of the fermenter and cover it with some sort of insulation.
3rd best is to hang it in the air and use a fermometer (they are very accurate)
worst is to put the sensor in a separate liquid.
:cheers:

#7

[quote=“TG”]+1

worst is to put the sensor in a separate liquid.
:cheers: [/quote]

Just curious why you say this, if one understands that the actual temp of fermenting wort might be a few degrees higher and adjusts accordingly. Also, I protect my probe from direct liquid contact with plastic.

#8

You want the sensor to be as close to the item being controlled as possible. Anything else causes delays in the control process (bigger swings in the temperature of the fermenter and less accuracy).
If the sensor is in the beer it is measuring the temperature of the beer (what you want to control).
If it is taped to the side of the fermenter, the temperature of the beer must transfer through the container wall before the sensor will measure it.
If the sensor is hanging in the air, the fermentation temperature must first heat up the container wall, and then the air before the sensor will measure a change.
If the sensor is in a separate liquid, the fermentation heat must heat up the container wall, which then heats up the air, which then heats up the other container wall which will then heat up the other fluid. If just delays the whole process.

You are using it as just an expensive thermometer and you are the controller. Try putting your thermowell into the fermenter and stand back and let it do its thing.

:cheers:

#9

Thanks for the responses. I went this morning to check, and the wort was into lager temps (52-56). I cut the controller, removed the jugs of water (some had ice in them from the day before when it was just a deep freeze), and left the lid open for about an hour. Hopefully, it’ll keep going up. I had to leave town for a few days, so I can’t monitor for the next few days. I set the probe in a jug of water (one without ice) and closed the lid.

Have I screwed up the sensor by putting it in water? I did this already. Based on what I’d read already

#10

They are covered with plastic so I don’t think it will fail immediately. Take it out and let it dry, then check its accuracy against another thermometer.

#11

I have the metal probe and the analog thermometer. It appears to be soldered and sealed, so I was a little surprised when someone said it needed to be covered. I just thought it was to prevent corrosion.

#12

Oh, the analog model. It comes with a set differential of 3.5degF. So you can’t use it to control the fermenter directly (unless you want it to vary by 3.5 degrees). In that case it’s best to hang it in the air and control the fermenter yourself.

The differential on digital models can be adjusted to 1 degF which would be more appropriate to control the fermenter.

#13

[quote=“TG”]Oh, the analog model. It comes with a set differential of 3.5degF. So you can’t use it to control the fermenter directly (unless you want it to vary by 3.5 degrees). In that case it’s best to hang it in the air and control the fermenter yourself.

The differential on digital models can be adjusted to 1 degF which would be more appropriate to control the fermenter.[/quote]

Thanks! I guess I should have spent the extra $20 and got the digital

#14

After arriving back into town, the temperature stabilized to about 64-66 degrees, and the fermentation is still going. This is the third full day (pitched Thursday afternoon around 5). How long should I keep fermentation at this temperature before I begin raising the temperature to finish out the fermentation? I ask because I’ve read where some suggest that you should raise the fermentation temp to the high end of the yeast’s ferm temp.

#15

I would not start raising the temps until at least a few days after all activity has stopped at the lower temps

#16

I would not start raising the temps until at least a few days after all activity has stopped at the lower temps[/quote]

Okay. I have left it at 70, and I’ll keep it there until the bubbles stop and I take a gravity reading. I’m excited bc this is the best I have ever been able to control the temp.

On a side note, the area behind the shed where the freezer is has been covered up with mosquitos that are attracted to the cO2 being pushed out by the beer. Interesting phenomenon.

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