Fermentation Chamber Help

Discussion in 'General Brewing Discussions' started by Zak2428, Nov 29, 2020.

  1. Zak2428

    Zak2428 New Member

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    Hey all,

    Recently I moved from FL to NC - in FL I was able to maintain my room temp at the exact temp range my beers needed for the SafAle 04 & 05 yeast that I had to use. With the move to NC and the obvious climate difference here, my room temp no longer fits the range I need, so I purchased an InkBird, 7 cu ft Chest Freezer, and small space heater thinking I could maintain the chest freezer at a set 69-70 degrees. However, after playing around with it, the heat and cold air from the freezer/heater were so delayed in maintaining that temp range, that i need some assistance or ideas on how I can better maintain the temp in my freezer...

    It's hard to explain, but basically this is my situation. I want to maintain the chest freezer at 69. The inkbird would turn the heat on if it dropped to 67 and would turn the freezer on if it rose to 71. However, once the heat is triggered at 67 it would raise the temp to 69 and shut off, BUT the air temp in the freezer would actually continue to rise to 78ish even though the inkbird turns my freezer on at 71. And vice versa, the freezer would go until it hits 69, shut off, but the temp would continue to lower to 59 even though my heater is triggered back on when the temp hits 67. The inkbird is triggering both to turn on and off at the right time, but the temp in the freezer is delayed.

    What am I doing wrong, or what would you suggest I do instead?
     
  2. Bubba Wade

    Bubba Wade Well-Known Member

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    Try this. Tape the sensor to the side of your fermenter. You might even put a bit of insulation over the sensor.

    What you are really concerned with is not the air temperature, but the beer temperature.

    The reason that the temperature would keep rising or keep falling is due to the low heat capacitance of the air. The coils in the heater are warmer than the air, so when the heater shuts off, heat continues to be absorbed by the air. And with low heat capacitance, the temperature continues to rise.

    If you measure the beer temperature, this has a high capacitance. When the heater (or chiller) shut off, the amount of heat available for transfer is small compared to the heat capacitance of the beer so the temperature will change very little.
     
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  3. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    Just out of curiosity, why such tight temperatures on S04 and US05? I found that S04 works better in the low 60's and US05 is known to go as low as 55F. At lower temperatures both yeasts are cleaner, especially S04. Or are you trying to get esters from the yeast? Then I understand why you wouldn't want the yeast to drop in temperature.

    Both yeasts work very well from 62-70F, but if your after esters, then raise the temp to 68-72F, S04 even higher.
     
  4. Zak2428

    Zak2428 New Member

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    Honestly, just from my past experiences those are the temps I've had the most success with. Plus, it was the only temp I could sit my beer in since it was the room temp down in FL - it was impossible to find a cheap chest freezer down there, so now that I have one available I need to figure out my set up so I can start using different yeast that utilize lower temp ranges. For SafAle 4 & 5, I'd be fine fermenting at the lower ends of these yeast ranges, but right now I just need to figure out how to minimize the temp fluctuations so I can avoid it hitting the two extremes of the yeast range. From my understanding, if it's fluctuating from both ends of the temp extremes, this would stress the yeast, would it not? Or, does it not matter as long as it's not dipping below or above the recommended range?

    Just an update - I've made a few adjustments to my set up and it's been sitting around 63-65 now, which is ideal. Going off of what @Bubba Wade mentioned, I also stuck a 1 gallon fermenter in there with just water to test what the liquids temp would sit at and it seems to sit mostly at 65 degrees. I'd imagine my 2 gallon batches would react similarly. I'm thinking about adding a small fan in there to help move the air around, I'm thinking that'll help? Idk, just trying to figure out the best way to set this freezer up to avoid high temp fluctuations - unless i shouldn't be too worried about it?
     
  5. west1m

    west1m Well-Known Member

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    Yes, add a fan
     
  6. Donoroto

    Donoroto Well-Known Member

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    As @Bubba Wade wrote, focus on the liquid temperature. For that, try a setup that measures that as closely as possible.

    My inkbird sensor is taped to the fermenter under some thin insulation (1/4" felt), and my Tilt hydrometer says temperatures stay fairly constant.

    You can (and should) set the inkbird to operate at a one degree temperature tolerance; write back if you need instructions.
     
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  7. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    Typically, the liquid doesn't swing in temperature like the air in the chamber. That's why the taping of the probe to the fermenter keeps the temperature from looking like it's swings from one extreme to another. The yeast can be pitched in cool, kept in a cool area and the temperature will rise as fermentation becomes more active. The beer can exceed ambient air temperatures from the exothermic activity of the yeast. Once the fermentations slows, the yeast stops producing heat and the temperature will drop if the ambient temperature is lower.

    So I'll pass on advice I got a while ago about S04, pitch low 62F or so and let it rise. It can peak @ 72-74F toward the very end and then the temperature will drop, the beer turns out fine. As long as the ambient temperature is around 66-70F, you'll be fine just leaving it in the room. Use the keezer for yeasts that require low temps, like Kolsch's, Alt's and even lagers. The keezer also works great for dropping yeast and hops when the beer is done. Cool the finished beer to 33F for a few days and get clearer beer.
     
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  8. Nosybear

    Nosybear Well-Known Member

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    On the other hand, if you use the thermowell, temperatures will yo-yo. Reason: The probe is in the center of the beer and (oversimplified, omitting convection) the beer warms and cools from the outside in. The effect is more pronounced with a freezer that cools faster than a refrigerator. Ask me how I know....
     
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  9. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    I guess I would politely disagree. The beer that’s in active fermentation is naturally be circulated by the escaping cO2. Even lagers churn in high krausen. The churning action keeps the internal temperature uniform. I’ve used thermal wells and never saw a big swing in temperatures. Not sure what you experienced.
     
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  10. Nosybear

    Nosybear Well-Known Member

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    I'm using a freezer as a fermentation chamber with a Fermwrap taped to the back to provide heat, if necessary. Likely has to do with the rate of cooling and the delay in the sensor reporting the change in temperature.
     
  11. 56 Firedome

    56 Firedome Active Member

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    I use a thermowell with my Inkbird with 1 degree up & 1 degree down in a cooling compartment cooled by a mini fridge. Not as powerful as a keezer but I've never seen more than that 1 degree variance.
     
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  12. BOB357

    BOB357 Well-Known Member

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  13. Donoroto

    Donoroto Well-Known Member

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    I have a SS fermenter and when I use the thermowell, temperatures swing 3-5 degrees (according to the Tilt), I went back to taping the sensor to the outside of the fermenter, with much better results. @HighVoltageMan! your mileage obviously varies but my own experience matches Nosy's. Not being able to see through Stainless I have to just guess that convective action isn't as forceful in my setup.

    Anyone want to buy a lightly-used 1.5" TC Thermowell?
     
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  14. Nosybear

    Nosybear Well-Known Member

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    I spent extra for the thermowell in my brew bucket.... Back when I was using a refrigerator for a fermentation chamber rather than an upright freezer, I didn't get the yo-yo temperatures using a thermowell. It cooled much slower, allowing the temperature to equalize throughout the beer. The upright freezer I'm using now, not so much. Wife and I have agreed to trade the upright for the chest freezer so I can build a keezer, then I'll switch back to using the refrigerator as a fermentation chamber, then I'll use thermowells again.
     
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  15. Donoroto

    Donoroto Well-Known Member

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    Hm. I wonder how I can fix the hysteresis issue when using the thermowell. Intuitively it should be More Better, but empirically it was not.

    Further research needed...
     
  16. Nosybear

    Nosybear Well-Known Member

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    Empirically: Tape the probe to the outside of the fermentor covered with a bit of insulation - I steal batting from my wife's quilting projects. Typical of any system, the hysteresis is caused by delay between the sensor and the actual state - it's a lot colder outside of the fermentor than where the probe is. By taping the sensor to the outside of the fermentor, the temperature falls slower but since the delay is on the cold side, it cools in increments and doesn't overshoot because the environment is only marginally colder than the sensor.

    You could hypothetically control the variation by thickening the insulation: The slower the probe cools, the colder the actual environment compared to the beer.

    It really gets ugly when you add warming to the mix: The cold side overshoots, resulting in a beer that is below temperature, which the warm side tries to compensate...
     
  17. Brewer Jim

    Brewer Jim New Member

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    I use a 16oz plastic Coke bottle filled with water. I have a 1/4" hole drilled in the cap. I leave my temperature probe inserted in the bottle. The water in the bottle will change quicker than the temperature in the fermenter. The bottle temperature will change 2 degrees before the temperature changes in the fermenter. So the bottle temp will have swings of 4 degrees but the temp of the fermenter remains constant.
    Also for the heating I use a little 5 watt bulb on an extention cord inside my chest freezer. Cheap and it provides all the heat i need.
     
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  18. 56 Firedome

    56 Firedome Active Member

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    Is that thermowell1.5" in diameter or 1.5" long? If 1.5 long that would barely reach the surface of the fluid. If 1.5 in diameter, that might represent air gap between the sensor & the fluid.
     
  19. BOB357

    BOB357 Well-Known Member

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    I use a thermowell and ferment in a fridge. Haven't had a problem with temperature swings during active fermentation.
     
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  20. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    That’s been my experience.
     
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