What's the best way to attached the temperature controller's therometer on fermenter?

[DrunkleJon]

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

Realize though that this is with a conical. A metal fermenter. You get a slightly different amount of insulation from plastic or glass so the reading can vary. I have no scientific proof of this other than the insulating factors of the materials of the fermenters themselves. Additionally, what we're the degrees of the beer over and undershoot. Is it really enough of a factor that there will be any noticeable difference? That is the beauty of brewing. You can be as strictly scientific as you want to be or as relaxed too. I for one will be happy to risk a fraction of a degree of variance for whatever extended lifespan and energy savings occur from fewer cycles.

 

[Natdavis777]

I used to do the Ambient air method, and it worked fine, as long as I kept ambient low and slowly ramp up. Until this killed my ferm chamber. What I mean is that my compressor kicked on God knows how many times a day, eventually causing an electrical failure to the compressor.

I tape it to the side of the carboy now, insulated in bubble wrap. The compressor doesnt kick on nearly as much, and the beer is still sitting at the desired temp. Ive never used a thermowell, so I cannot comment.

 

[Scriv]

I use a thermowell

 

[balrog]

I tape to the side. I use plastic bucket. I insulate. My ferm chamber leaves 2"-3" space on all sides of bucket, nearly 6" above. I have a PC fan running constantly. I use simple (no PID) STC+ with 1/2° hysteresis from set point temp.

Having said all that, I can tell a difference, during stable post-fermentation exotherm, of the cycling of the ferm chamber, depending on whether I rotate the bucket side with temp sensor near the mini fridge side that cools the chamber or away from it.

One man's experience.
Brew on.

 

[JC_Brewer]

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.

 

[KartRacer54]

I use a Velcro strap around the fermentor with RC battery padding.

 

[bondra76]

I do a blowoff tube, and feed my STC-1000 temperate probe through the tube and directly into the fermenting wort.

No need for thermowell.

 

[doug293cz]

Realize though that this is with a conical. A metal fermenter. You get a slightly different amount of insulation from plastic or glass so the reading can vary. I have no scientific proof of this other than the insulating factors of the materials of the fermenters themselves. Additionally, what we're the degrees of the beer over and undershoot. Is it really enough of a factor that there will be any noticeable difference? That is the beauty of brewing. You can be as strictly scientific as you want to be or as relaxed too. I for one will be happy to risk a fraction of a degree of variance for whatever extended lifespan and energy savings occur from fewer cycles.

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

 

[doug293cz]

"Best" way is a thermowell stopper, and they're pretty cheap ($20), so that's what I use.

But in another thread you say this:

I've been using a 60W lightbulb covered with a metal coffee can. However, I've been having a lot of trouble stabilizing fermentation temperatures. I brewed a Kolsch last weekend and put it in my chest freezer with the aforementioned lightbulb, and the STC-1000 set to 16.5° C +/- 0.3° C, with the temperature probe in a thermowell stopper in the glass carboy.

I found that the temperature would swing wildly. I was seeing temperatures everywhere from 13.5° C all the way up to 19° C. It seems when the light bulb came on, the chamber would get so warm, and was so well insulated, that when the beer reached the desired temperature, it just kept getting warmer.

Anyway, I've removed the light bulb and replaced it with a heating belt my wife used to use for wine making (which I probably should have just used in the first place). The temperatures seem MUCH more stable now.

This other post describes experiences that are consistent with what I said in posts #30 & #38 above.

Brew on

 

[kombat]

I don't think that's a "but" as much as it's an "and." There's nothing inconsistent there. I was using a thermowell in both cases. The problem was the light bulb, not the thermowell. Now that I'm using a heating belt (with the thermowell), I'm getting very stable temperatures.

 

[azazel1024]

Ace bandage works a treat.

 

[DrunkleJon]

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.

Good point. And knowing your system is really what matters most. You chould chill your chamber with a block of dry ice and heat it with a blowtorch, and tighten up the swing once you figure out which works best for you. Extreme cases I know. My point was that gentle heating and cooling (non contact, no heatsink radiator, etc) should not carry over enough heat or cold generation to swing 5 gallons+ worth of liquid more than a fraction of a degree. Then again whatever works best for you, accept swing or work out how much insulation you need.

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

Very true. like above, find the balance for your system.

In my opinion though, and feel free to disagree, even a 1 degree over/under swing really should not cause any appreciable difference with fermentation. Compared to professional jacketed multibarrel systems where the beer inside can vary in temperature throughout the entrie fermenter by more than that during peak fermentation our temps can be even more tightly controlled.

 

[ChucknBeer]

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

Question: during his tests, he opened the fermenter and check the inner temperature of the beer?

I use a thermowell and in fact, one of my concerns with it was that the probe is almost in the middle of the beer mass. So, while the temp in the core can be 18°C, the temp in the outer beer mass (near the bucket walls) might be lower. This, of course, without having any knowledge of tempt transfer in liquids.

The first time I used the thermowell, I was constantly checking how long it took the fermenter to go to the desired temp and how much time it took to go above the range set in the STC-1000. This was during summer, with temps of over 30°C. It took the beer more than an hour to go from 19°C to 19.4°C, starting the compressor. After the fermenter reached 19 again, the temp usually kept dropping like 0.2 additional degrees, until it started going up again... all this during fermentation.

A variation of 0.6°C for a primitive ferm chamber seems quite ok for me.

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... I could be totally off, anyways.

 

[TennBrewer]

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.

 

[DrunkleJon]

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.

For a Kegerator/Keezer this works. For a fermentation chamber the temperature of the fermenting beer is what you want to measure as fermentation gives off heat which will mean that your fermenter full of beer is actually going to be warmer than the jug of water that you are measuring the temperature of.

 

[JC_Brewer]

Question: during his tests, he opened the fermenter and check the inner temperature of the beer?

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. I then swapped the setting on the controller for which probe was controlling the ferm chamber. Comparing the results of the two, the beer temperature was kept more constant while the chamber was being controlled by the probe on the side.

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.

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...

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.

 

[wardens355]

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.

This is a very important point to make. The wort is churning around during the early phases of fermentation that create the most heat, so there shouldn't be much of a temperature gradient between the center and edge of the carboy. This is also the most important time to control temperature. The temperature of air or a mass of tap water will have a considerable delay before reaching the temperature of the wort as it rises. Once activity dies down, little heat is produced, so measuring at the side of the carboy, or just air even, will probably be fine.

 

[jignn]

I tape it to the side of the fermenter under a couple small pieces of pipe insulation, a few inches below the top of the liquid level.

 

[ChucknBeer]

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.

Ah, I missed that part, you have both thermowell and side probes in the same fermenter.

Edit: was there a relevant temp reading diff between both probes?

 

[Gavin C]

.....great stuff about data.

Hey JC

Just wanted to pass on that this data of yours has saved me from purchasing thermowells. Thanks very much. I am in your debt.

This topic comes up all the time and it was in another thread that your data was mentioned showing "probe on the side" to be better than a thermowell in controlling beer temps. Can you share a link to the experiment you did? Would love to read more about it.

It seems the exothermic nature of fermentation seems to flummox a lot of people as repeatedly, talk about monitoring the ambient temperature in the chamber in the hopes of controlling fermentation is read in thread after thread. This one being no exception.

Granted if you do not have an STC1000 or similar controller, setting a desired ambient is the next best thing. But deliberately controlling ambient in a chamber negates the benefits of using a controller if you already have one.

One way to look at the issue albeit from a very different angle is this.

If you are cooking a steak on a grill and you want medium rare. You don't monitor the ambient temp of the grill. Everyone would agree that that would be nonsense. It's the meat temperature you monitor.

Change meat to beer, grill to fermentation chamber and the same laws apply, the only crucial difference being that fermenting beer will add heat to the system.

Anyway. Thanks again.

 

[JC_Brewer]

Just wanted to pass on that this data of yours has saved me from purchasing thermowells.

You're welcome. I think that thermowells still provide value in that you are able to better monitor the temp of your beer so that you can adjust your controller's setpoint to how it's keeping the beer where you want it.

I haven't published my findings anywhere. They're just scribbled down in my brewlog. I'll document my experiment again the next time I brew and take some screenshots of the temp logs so people can see my results instead of simply taking my word for it.

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.

 

[SpeedYellow]

...



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.

Sounds like your combination of heater, cooler, differential set point, etc. wasn't working well for the thermowell. But of course thermowells work perfect for a great many of us.... my beer temp always stays within the 0.3C differential. SS Brew Bucket, thermowell, STC-1000, 5 cu ft freezer, two seed mats wrapped around fermenter. I especially like the thermowell because I know exactly the beer temp -- no guessing.

I didn't realize it was so equipment-sensitive. Interesting info!

 

[grainbill]

that's how I was taught, been doing it that way for about 18 years, no issues, temp is spot on when taking gravity reading

 

[grainbill]

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 how I was taught, been doing it that way for about 18 years, no issues, temp is spot on when taking gravity reading

 

[grainbill]

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.

that's how I was taught, been doing it that way for about 18 years, no issues, temp is spot on when taking gravity reading

 

[AQUILAS]

Well since this thread of mine is still ticking, I'd thought I'd give another update.

It's been a week and a few days since I've used the tape-probe-to-bucket way and it's been working perfectly. Again, I taped the probe to a coozie, taped another coozie to the back of it for extra insulation, and then religiously taped it to the side of my fermenter, right next to my fermometer.

My fermometer and probe have been reading the same temperature this whole time. Hit my target gravity after one week and no off flavors. Actually, it tasted really close to the beer I'm trying to clone.

All has been well with this method and with how my fermentation went as well as some of the discussion here, I may stick to this method for the long haul.

 

[PCL]

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

 

[doug293cz]

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 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.

Brew on

 

[dstockwell]

I tape to the side of the bucket about mid way with bubble wrap on top of the sensor.

 

[PCL]

Thanks mug and dstockwell.

I will try that out.