azazel1024
Well-Known Member
Ace bandage works a treat.
I'll also add that when I did this experiment, I was logging both locations (thermowell and on the side) at the same time during primary fermentation and comparing the two locations while under the same conditions.
I agree that stainless transfers temperature differently than glass/plastic but stand by my results for my system. If I used carboys, I would do the same thing because of the amount of time it takes to change the temperature of liquid.
I don't feel that via a thermowell would give you as tight temperature control unless you had a PID controller automatically adjusting.
But hey, in the end we're still making beer.
For best results you would want to balance the amount of insulation on the outside of the temp probe vs. the thermal conductivity of the fermenter. You want most of the temp input to come from the beer, but a significant fraction (maybe 20-30%) to come from the chamber. So, with stainless you would need less insulation than with plastic or glass.
Another thing you want to balance is the wattage of the heat source if you have one. Too high a wattage on the heater will cause the chamber to cycle more than a lower wattage. (It'd be nice if you could also easily balance the cooler power, but that's a lot harder to do than change heaters.) You want just a little more heat available from the heater than the chamber loses to ambient. Of course the heat lost by the chamber will vary depending on the temperature outside of the chamber.
Brew on
Question: during his tests, he opened the fermenter and check the inner temperature of the beer?Whole lot of opinions on this thread that are not backed up by data. @JC_Brewer has logged thermowell vs. taped on side, and found that the beer temp is more stable when probe is taped on the side. If anyone saying that the thermowell placement provides lower beer temperature swings than taping on the side has temp logging data comparing the two, please post it here. What is your goal?
- Stable beer temps? Then tape the probe to the side.
- Longer cool/heat cycle times? Then use a thermowell.
There is solid thermodynamic science behind why taping on the side provides more stable beer temperatures than a thermowell. The lag time in the temperature response of a thermowell, due to the high thermal mass of the fermenter contents, does cause the chamber temp to over and undershoot significantly. The chamber over/undershoots cause smaller, but still significant, over and undershoots in the beer. By having the probe taped to the side of the fermenter, the chamber temp has some influence on the temperature reading. When the chamber temp starts to undershoot, the probe reading drops a little lower, with the net result being that the cooling is shut off sooner. This results in less chamber undershoot, and therefore less beer undershoot. The same thing happens when heating.
Brew on
Best method for me initially was to put the probe in a jug of water inside the ferm chamber. After awhile, all liquids inside should come to the same temperature and the more thermal mass you have, the more stable the temperature. I now use a homemade thermowell I fashioned by crimping the end of a piece of hard copper tubing and a bit of melted wax (like paraffin used in canning) to seal the crimp.
Question: during his tests, he opened the fermenter and check the inner temperature of the beer?
Because I was logging data from both probes at the same time, I actually had a very good "idea" of the temp of the beer mass under both conditions.Having the prove attached to the side of the bucket might show more stable temp ranges, but you have no idea what is the temp inside the beer mass...
During primary fermentation, I wouldn't think that there would be as much of a temperature difference throughout the fermenter because, having watched beer ferment through a carboy, it's moving around pretty good.
Ah, I missed that part, you have both thermowell and side probes in the same fermenter.I didn't have to open the fermentor because as I previously stated, I had two probes; one in a thermowell (measuring beer temp) and the other on the side so I could view the logged temperature of both of them at the same time to compare the difference.
.....great stuff about data.
Just wanted to pass on that this data of yours has saved me from purchasing thermowells.
...
If my memory serves me right (my brewlog is at home), the beer temp was swinging 4 degrees (+/- 2 degree swing) from the setpoint while being controlled via the thermowell. It was less than a degree when it was being controlled on the side of the fermenter. It may not be enough for some to consider that big of a difference but I like my brewing processes to be consistent and repeatable. Especially temp control during primary fermentation.
But.. Fermenting wort creates heat. If you are measuring ambient/chamber temp rather than the beer itself, you are probably a few degrees of during peak ferment. Measuring the outside of the fermenter is a decent middle ground to a thermowell.
That's definitely the worst possible way to control beer temp. You're merely measuring the ambient air temp, except you've insulated the probe from what you want to read. It's like measuring air temp but jacking up your t'stat's differential. The result is larger swings in air temp (both hot and cold) and thus larger swings in beer temp.
You could of course measure in this cup of water but set the differential really low and that might be reasonable, but you're still measuring the wrong thing. We care about *beer* temp, so ideally we should measure beer temp (thermoprobe). The next best is the fermenter wall. Next best is the air temp. Worst thing is something else like a cup of fluid or block of metal sitting in there.
If you had about a 4" gap between the ends of the brew belt when wrapped around the fermenter, then center the probe in the gap, you should be ok.I am working on putting together my fermentation chamber, and this thermowell vs. side-taped thermometer has been very helpful. Thank you all.
Question: I was looking into heating options for my chamber. Initally I was thinking brew belt (for several reasons) and thermowell. Now that I am leaning against the thermowell, is a brew belt out of the question? It seems it would heat the vessel (bucket vs big mouth) and (perhaps) falsely elevate the measured temp over acutal internal beer temp. Anyone have any input on this?
Thanks in advance,
PCL
If your using a STC1000 taped to the side is fine, if your using a PID based BrewPi or something you should use a thermowell.
Because there is no prediction from the STC1000 your going to probably have quite a bit more overshoot if you have it in a thermowell i would think? But i guess that depends on the efficiency of your fermentation chamber, and if your using a freezer or a fridge. A freezer will obviously overshoot a lot more because they get so much colder.
The degree of overshoot with a thermowell depends on a number of factors:If your using a STC1000 taped to the side is fine, if your using a PID based BrewPi or something you should use a thermowell.
Because there is no prediction from the STC1000 your going to probably have quite a bit more overshoot if you have it in a thermowell i would think? But i guess that depends on the efficiency of your fermentation chamber, and if your using a freezer or a fridge. A freezer will obviously overshoot a lot more because they get so much colder.
But during normal operation with a 0.5F differential and a reasonably sized heater wrapped around the fermenter, you won't see much overshoot at all with a thermowell.
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