How are You Measuring Fermentation Temperature?

[Clint Yeastwood]

How do people here measure the fermentation temperature of their beer?

When I got started back during the early 90s, I assumed that if a recipe said to ferment at x degrees, I was to set the fridge at x and not measure the temperature of the beer. I had no way to check on the beer itself. I figured everyone else did it the same way.

I haven't really changed anything, since the beer comes out fine.

If I see a recipe for beer, can I assume the listed fermentation temperature is the actual temperature of the beer, or are there old recipes that just give the temperature of the surroundings?

Seems like it would be difficult to keep the beer temperature steady, since the yeast will give off different amounts of heat at different stages of fermentation.

Are people using those little strips that stick to the sides of fermentation vessels, or what? I have laser thermometers, but they're not ideal for measuring the temperature of shiny objects like kegs. I have used a marker to blacken little spots on kegs, and I shine my laser thermometer at the marks. Don't know if it actually works.

 

[DBhomebrew]

Seems like it would be difficult to keep the beer temperature steady, since the yeast will give off different amounts of heat at different stages of fermentation.

That's why one might measure the beer temp. Depending on size of batch and gravity, the beer temp can be 5+° over ambient. Your car's thermostat measures oil temp, not ambient, yeah?

Tape your controller's probe against the side of the fermenter with a piece of foam over it. Keeps my ferments' temp rather steady. Within the +-1° of the controller.

 

[corkybstewart]

I have a thermometer in a thermowell connected to a temperature controller which is connected to a window AC in a well insulated( but ugly) plywood box. The thermometer measures the temperature in the middle of my 12 gallon conical.

 

[BeerNsteadofH2O]

All of my fermenters have thermo wells, the probe's go back to inkbird controllers, each fermenter has heaters and cooling capacity, I calibrate my inkbird controllers with ice water.

 

[sibelman]

I still do it the way @Clint Yeastwood does. No disrespect to methods of gettingcloser to the beer itself. I generally set the controller to the low end of a yeast's declared temperature range, recognizing that during active fermentation the wort-becoming-beer will be closer to the middle of the range.

 

[BrewZer]

I'ma use the Inkbird dual temp controller ITC-308's thermocouple taped to the side of my fermenter for an instant read. I augment that with an Inkbird IBS-TH2 recording thermometer so I can has a record.

 

[Clint Yeastwood]

I found a thread with a post claiming a bunch of guys compared internal and external temperatures and found the difference was like half a degree. My fridge swings a lot more than that.

My Inkbirds don't claim to be very accurate.

 

[day_trippr]

[raises hand] I'm one of those guys who experimented with thermowells vs side-strapped insulated sensors and found the differential readings to be within 1/2°F of each other...

Cheers!

 

[DBhomebrew]

I found a thread with a post claiming a bunch of guys compared internal and external temperatures and found the difference was like half a degree.

[raises hand] I'm one of those guys who experimented with thermowells vs side-strapped insulated sensors and found the differential readings to be within 1/2°F of each other...

Are y'all talking about the same thing? Or is Clint talking about internal vs ambient?

It makes sense that the thermowell vs insulated side strap is pretty close. At the time of most exothermic activity you also get a significant amount of movement within the beer.

 

[DonT]

When I first started brewing, we measured the beer temp with a dial thermometer placed on the floor next to the bucket.

Later in life I built a fermentation chamber around a mini fridge controlled by Inkbird. The temp probe was taped to the side of the fermenter. Worked pretty well....

These days I have an Inkbird controlling a glycol chiller with the probe in a thermowell of a SS bucket...

How times have changed....

 

[jerrylotto]

Bottom line is that if you only control the ambient temperature, you're going to have wide swings in the fermentation temperature. Fermentation is initially exothermic and so it's going to be hotter than the environment, eventually evening out.

 

[Clint Yeastwood]

How much hotter? How much control can you get with a crude system using an Inkbird and Home Depot freezer? Does it actually work?

Is the beer any better? That's all that matters.

An Inkbird may be off by 4 degrees. Does anyone here calibrate them before using them?

 

[Clint Yeastwood]

When I first started brewing, we measured the beer temp with a dial thermometer placed on the floor next to the bucket.

Later in life I built a fermentation chamber around a mini fridge controlled by Inkbird. The temp probe was taped to the side of the fermenter. Worked pretty well....

These days I have an Inkbird controlling a glycol chiller with the probe in a thermowell of a SS bucket...

How times have changed....

How much has the beer improved?

 

[jerrylotto]

How much hotter? How much control can you get with a crude system using an Inkbird and Home Depot freezer? Does it actually work?

Is the beer any better? That's all that matters.

An Inkbird may be off by 4 degrees. Does anyone here calibrate them before using them?

Yes, I calibrate them because I use different probes that are permanently installed in my fermenters. And yes, my beers have gotten much better since I've been controlling temperature by the thermowell. Even if the calibration is off slightly, the variation is plus or minus 1 or 2 degrees. There can be as much as a 10° swing during the exothermic phase of fermentation if you're not actively, overcooling.

 

[DBhomebrew]

An Inkbird may be off by 4 degrees. Does anyone here calibrate them before using them?

Yes

 

[JohnDBrewer]

Inkbird in a thermowell with the fermenter sitting in an upright freezer.

Yes I calibrate my thermometers once a year or so.

 

[day_trippr]

There's zero doubt that controlling fridge or freezer compressors using comparatively tightly coupled sensors provides a significant advantage wrt controlling fermentation temperatures that simply cannot be matched using "ambient" temperature sensing. Never being concerned with a fermentation running outside a yeast strain's optimal operating range is A Good Thing

Cheers!

 

[corkybstewart]

How much hotter? How much control can you get with a crude system using an Inkbird and Home Depot freezer? Does it actually work?

Is the beer any better? That's all that matters.

An Inkbird may be off by 4 degrees. Does anyone here calibrate them before using them?

I've been brewing since 1992. The single thing that I did to make my beer substantially better was to control the fermentation temperature with my thermowell and insulated box. Being able to ferment near the lower temp range for a particular yeast, keeping the temp consistent, reduced the phenols and higher alcohols that created off tastes in my beer. My buddy and I brewed 40 gallons one weekend. 3 of the 10 gallon batches fermented with temp control, one was just in a closet at about 65F. The uncontrolled batch was awful compared to the other 3.
There's no doubt whatsoever that temperature control is important.
I don't know anything about the Inkbird, and using an external mounted controller, I've used my system since around 2005, before Inkbird I think.
The thermometer tape glued to the side of my conical is handy, and is usually within a couple of degrees of my controller, but it's just a convenient visual aid.

 

[Clint Yeastwood]

I should have said Inkbirds could be off by two degrees, not four. I blame the ungodly hour.

So who has seen a real improvement in beer after switching to internal measurement? Who has not seen a real improvement?

For what it's worth, apart from the built-in inaccuracy of the Inkbird, my fridges swing quite a bit while I'm using Inkbirds. If I set one for 65, I may walk by and see a temperature over 67. So does random walk cancel out the swings and put me at an average of 65?

 

[Clint Yeastwood]

I've been brewing since 1992. The single thing that I did to make my beer substantially better was to control the fermentation temperature with my thermowell and insulated box. Being able to ferment near the lower temp range for a particular yeast, keeping the temp consistent, reduced the phenols and higher alcohols that created off tastes in my beer. My buddy and I brewed 40 gallons one weekend. 3 of the 10 gallon batches fermented with temp control, one was just in a closet at about 65F. The uncontrolled batch was awful compared to the other 3.
There's no doubt whatsoever that temperature control is important.
I don't know anything about the Inkbird, and using an external mounted controller, I've used my system since around 2005, before Inkbird I think.
The thermometer tape glued to the side of my conical is handy, and is usually within a couple of degrees of my controller, but it's just a convenient visual aid.

I get it, but a closet is a lot different from a freezer with an Inkbird with the probe outside the vessel.

 

[DBhomebrew]

If I set one for 65, I may walk by and see a temperature over 67. So does random walk cancel out the swings and put me at an average of 65?

Your imperial stout may very well be hitting 75 at times, never getting down to 65 until fermentation is near complete. To bring an actively fermenting beer down to 65, ambient has to be appreciatively lower than beer temp. To maintain an exothermal entity at 65, ambient has to be appreciatively lower than 65.

The fact is that the yeast care what temperature the beer is, not what temp the ambient is. Measure and control what matters.

With the inkbird's probe on the side of the vessel protected from ambient with a square of foam, the inkbird never goes outside the +/-1.1° of the set temp. That's beer temp. The temp in which the yeast are working.

Does it make better beer? Do it for yourself and find out. It's not like you'll be convinced by any number of forum members' reports from experience.

 

[Bassman2003]

Clint, it sounds like you are wanting to stay with controlling the ambient which is fine. But the probe on the side is better. How quantifiable might be difficult to know but yeast like certain things and work better if they get those things.

I use a David Heath suggestion of plumber's putty of the Inkbird probe on the side of my fermenter. Works great. The Inkbird is very affordable so it is a cheap upgrade to the best way to do it.

I find for style like Belgians and Hefe, precise control over the upper range of temperatures is very important and not possible with control ambient only. This is some of what Corky was mentioning. The difference of getting into fusel territory or not.

 

[Clint Yeastwood]

I'll do whatever works best, but if no one can say one way produces better beer, then one way is as good as the other.

 

[DBhomebrew]

Yeah. Nobody on this thread has put forth any reasons whatsoever why measuring beer temp rather than ambient might be better.

 

[Clint Yeastwood]

Here is what's on my mind.

 

[DBhomebrew]

Doing a secondary is not likely to improve your beer. On the contrary. Very few trusted sources still suggest it on the homebrew scale.

Taping a probe to the side of a fermenter is #993 on my Top 100 list of brewing hassles.

Do it, don't do it. I'm sure you'll make the world's greatest beer either way.

 

[mac_1103]

The hassle of taping the probe to the outside of the FV with a little bit of foam insulation is approximately zero.

 

[Clint Yeastwood]

So a probe on the outside works? What if the beer is cooler toward the outside due to the lack of convection?

 

[DBhomebrew]

As fermentation winds down and convection reduces, the ferment becomes less exothermic. The temp gradient across the radius of the fermenter is reduced.

An insulated probe taped to the FV is much much better than measuring ambient.

A thermowell is marginally better than the taped probe.

 

[mac_1103]

So a probe on the outside works? What if the beer is cooler toward the outside due to the lack of convection?

So we're back to the difference between middle of FV and side of FV vs middle of FV and ambient. You cited "a thread with a post claiming a bunch of guys compared internal and external temperatures and found the difference was like half a degree." What is the definition of "external" in that thread - side of the FV or ambient? My own experience is that temperature measured by a probe taped to the outside of the FV with some insulation can be 6F higher than ambient. I've seen others claim 10F. Middle of FV vs side of FV should be a much smaller difference.

 

[Clint Yeastwood]

So it sounds like tape is a compromise between hassle and accuracy that works considerably better than nothing.

I should get a thermowell lid for one keg and make a lager called Hasselbrau.

 

[DBhomebrew]

So it sounds like tape is a compromise between hassle and accuracy that works considerably better than nothing.

With insulation, yes. Absolutely. Minimal to no hassle, minimal compromise on accuracy from thermowell, massive improvement over ambient.

I use a square cut off an old blue foam camping pad. I've also used a bubble wrap lined shipping envelope.

 

[Knightshade]

I tape an inkbird probe to the side of my keg which has a little insulating pocket I sacrificed from an old beer koozie. It is set to a 1.5 degree differential based on what my Tilt is telling me is the internal temp.

 

[redrocker652002]

I have not read thru all the posts, but for me, I simply tape the probe of the Inkbird to the side of the fermenter bucket about halfway between the top of the beer and the bottom of the bucket. I tend to set my temp in the middle of the yeast range, so I figure a degree or two isn't going to be too bad. Plug my dorm fridge turned Ferm fridge into the Inkbird and it seems to be working ok so far.

 

[Bassman2003]

Clint, not sure why you created the post if you do not want to change what you are doing already? (which is fine).

Just think about it logically - there is no way ambient air temp can represent what is needed for 3-10 gallons of liquid that has an internal heat source.

My last ferment I noticed the wine fridge temp was reading 54F and I had the Inkbird set to 65F. So that is 11 degrees of compensation to maintain the 65F from a touching the outside measurement. Could be a bit warmer inside. If that was ambient cooling only it might be 75F inside.

If you do not have an Inkbird then it is settled. Or if you do not want to get one. But the "proof" is clear I do not want my beer at 75F when I think it is at 65F

If tape is an issue use the plumber's putty. I stick it on the wall of the fridge in between brews.

 

[Skeeter686]

I can say that I was very surprised the first time I actually had a thermowell in the fermenter and could see the temperature rise. It was something like an 8°F temperature difference. I assumed it would be a couple degrees higher than ambient, but it was closing in on 10 degrees which put me at the top of the recommended temperature range for the yeast I was using. I started more active cooling at that point to keep it from climbing even higher.

 

[corncob]

How much hotter? How much control can you get with a crude system using an Inkbird and Home Depot freezer? Does it actually work?

Is the beer any better? That's all that matters.

An Inkbird may be off by 4 degrees. Does anyone here calibrate them before using them?

I use a thermapen to measure every gravity sample. I figure if my inkbird (or other old controller) starts to drift, I'll catch it. So far, it's within a degree. That's probe taped to the side, no foam.

 

[Clint Yeastwood]

Clint, not sure why you created the post if you do not want to change what you are doing already? (which is fine).

Just think about it logically - there is no way ambient air temp can represent what is needed for 3-10 gallons of liquid that has an internal heat source.

My last ferment I noticed the wine fridge temp was reading 54F and I had the Inkbird set to 65F. So that is 11 degrees of compensation to maintain the 65F from a touching the outside measurement. Could be a bit warmer inside. If that was ambient cooling only it might be 75F inside.

If you do not have an Inkbird then it is settled. Or if you do not want to get one. But the "proof" is clear I do not want my beer at 75F when I think it is at 65F

If tape is an issue use the plumber's putty. I stick it on the wall of the fridge in between brews.

I'm not being obstinate. I'm trying to ask hard questions to get the best answers. I guess it's the lawyer and scientist in me. I plan to try the foam thing on my next beer.

The mods changed one of my posts to say I started brewing in the Nineties! I started in '02. I made the mistake of saying I started under Bush I when it was really Bush II.

 

[Jonakr]

I'ma use the Inkbird dual temp controller ITC-308's thermocouple taped to the side of my fermenter for an instant read. I augment that with an Inkbird IBS-TH2 recording thermometer so I can has a record.

I just have the 308. It's set to the lower range of my two primary yeasts, so I just tape the thermocouple to my current new batch and let it run.

 

[CDS]

I've always just measured ambient too. I've got an Inkbird 308 regulating the temp inside a fridge holding my 14-gallon conical. The plumbers putty idea seems like a low-overhead method if it's really going to make a difference. Does the fermenter material matter? I notice in David Heath's video, he was demonstrating on a plastic fermenter - any reason to think a stainless steel fermenter would be different?