Temperture deltas

Discussion in 'General Brewing Discussions' started by Ward Chillington, Sep 8, 2019.

  1. Ward Chillington

    Ward Chillington Well-Known Member

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    Of the 2 things that I wanted to toss out to the forum, these are both matters of my personal experience so please, no body interpret this as me telling anyone they are wrong...so disclaimer done

    My brewing goal this past year has been to do my best to be consistent in my brewing process so that I can monitor what the changes that I have purposely made have really done what I expected them to do and with the help of my own engineering experience has bought to this art, I wanted to back things up with measurable data and not hunches or taste or anything subjective. The inspiration for this has come from this forum and other forums along with a whole lot of commuter hours listening to the Brulosophy Podcast ( thank you Thunder Wagon for turning me on to that)!

    This last batch was to see for myself what the tempature on the outside of my glass Carboy and the temperature of the wort deep inside of the carboy as I had been reading that there could be enormous differences and that you really cannot expect to truly control your wort without knowing what your wort's tempature really is. A third variable was to see if those flexible stick on thermometers were usefully "close enough". My outcome was that there was never more then a 1 degree difference between the 2 and yes, the core temp was always the warmer of the 2.

    My methodology was to use my 2 Inkbirds that are always within point one ( 0.1) degree Fahrenheit of each other when measuring air temps. My "A" probe was stuck to the side of the 6 gallon carboy covered with some fiberglass insulation to isolate from the ambient air temp. Probe "B" was in a 12 " SST thermowell sharing space with my fermentation lock. I pitched my yeast last Sunday evening at about 75° then proceeded to further cool the batch down to the optimal range (59 to 71° F) for the Safale 05 dry yeast that I sprinkled directly onto the wort, no rehydration this time. As things cooled down to 67°F to following morning I could see we had some early signs of life with a burp or 2 every 70 seconds but no sign of krausen and .2° delta between the probes. With that, let the monitoring begin!

    14 hours later we had a minor krausen going and had bumped up the wort temps by 1 degree and the yeast were doing their thing with off gassing happening every couple of seconds and some 11 hours later the next morning we were mid krausen, off gassing on the second and the probes both at 69.1°F. That night at full krausen the glass probe was at 69.6 and the thermowell was lower at 69.1°. At this point with the air temps in the basement climbing to the low 70's I reached for the swamp cooler method to keep things below 70° so the yeast would not peter out too fast creating the wrong esters in this batch of Red Trolley clone. I'm ending the week now at 68° and things starting to flocculate so no more swamp cooling.

    Now the plan is to give things another few to 4 days of rest before going to the bottles.

    With my temperature control methods a bit crude without a refrigeration chamber, I have been able to keep things within a five degree range overall which is fine with me but what I have proved to myself is that I do not have an enormous difference to concern myself with and that I am going to find a different use for that thermowell because my probe taped against the glass and the probe in the well and the cheapo tape on thermometer were all indeed close enough for what I am attempting to achieve; brew some decent beer at home for a decent price over and over!


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  2. thunderwagn

    thunderwagn Well-Known Member

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    Nice informative little endeavor! I've seen several similar write ups on the accuracy of the cheap little sticker type thermometers. The ones I've read where the tester actually did test and not just guess or post what others posted, generally do seem to vouche for the accuracy of these stick on type thermometers.
    Pretty cool I think!
     
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  3. Bubba Wade

    Bubba Wade Well-Known Member

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    In the winter, I use two temperature controllers, one for heat and one for cool. I use a stainless fermenter with a neoprene jacket. The cooling probe goes in a thermowell and the heating probe is placed on the outside of the fermenter underneath the neoprene. Similar to your observations, I never see more than two degrees difference between the two.
     
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  4. Craigerrr

    Craigerrr Well-Known Member

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    Thanks for the write up! Based on this, I think I may forgo the thermowell for the probe, and fix it to the outside of the carboy. Making 10 gallon batches, I have 2 carboys, I will pick up a couple of those stick on thermometers to see if they are close in temperature. I have noticed slight differences in the beer from carboy1 and carboy2, maybe it is temperature related...
     
  5. Trialben

    Trialben Well-Known Member

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    Very well written ward. I've always just taped the probe to the outside so gives me a little ease of mind knowing it's not to far from the actual internal temp. Cheers!
     
  6. BOB357

    BOB357 Well-Known Member

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    Good observations. A thermowell is a great tool if used properly, but definitely isn't an end all be all.
     
  7. Ward Chillington

    Ward Chillington Well-Known Member

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    Pretty much my method in the winter Bubba, sans neoprene! The cellar can be down in the 40's when the cold weather get here so I'll be doing some lagers and wifey's fave, a Kolsch, again but no honey. I'll just be keeping the probe on the glass and compensating for the delta via the Inkbird.
     
  8. BarbarianBrewer

    BarbarianBrewer Well-Known Member

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    I ferment in a chest freezer controlled with an Inkbird. I was always curious how much warmer the wort was over ambient so I did a similar test. I borrowed a Tilt Hydrometer to measure the wort temperature and used the inkbird to control the temperature inside the fermentation chamber. In a room temperature, plain water calibration test they were 0.1* F apart. At max fermentation activity the wort was approximately 2-3* F above ambient. I was brewing a 1.060 OG Irish Red.
     
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  9. hundel

    hundel Member

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    This is a wonderful writeup. Really enjoyed reading about something I ponder just about every time I check on my wort. The one thing I’d say (and it’s been said here before) is that a lot of brewing wisdom is about reducing failures that are the result of anomalies. I think most of our published beer experiments are along the lines of “one time I did X and unexpectedly no one could tell the difference” when a lot of the guidance we’ve been handed down is along the lines of “if you do X enough times sooner or later you are going to have a problem”. That said I appreciate the approach and the desire to share the results here!
     
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  10. Ward Chillington

    Ward Chillington Well-Known Member

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    Thanks Man!
     

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