Yes, Virginia, fermentation temp control really IS important.

Okay, time to stir the hornet's nest...

I see folks on here suggesting that "Oh, US-05 should be fine up into the mid-70's, no problem... It's a very tolerant yeast."

Sorry guys, that's not true. Yes, it'll ferment up there. Yes, a lot of yeasts will ferment up there without turning out terrible beer. But if you want commercial quality beer, you need temp control. There's no other way around it.

It's simple. You ask a brewer who has temp control what his top three brewing processes leading to good beer are, and I guarantee temp control will be in the top three. It'll often be #1 on the list.

As brewers, we're all proud of the input we have into the process. We ogle over brewporn; beautiful single-tier HERMS setups with total automation. We obsess over mash temp, and boiloff rate, and every little bit of brew-day minutiae.

But you know what? You can screw up most of that and still have a pretty damn tasty beer if you keep your yeast cool and happy (I know, I've done it). And you can do everything else perfectly on brew-day, but if screw up your yeast, your beer will be sub-par.

Last year I did an experiment with another brewer. On my system, we brewed 15 gallons of DIPA, while I can only ferment 10. So I drew off 5 gallons into his carboy and put the rest in my fermenter. *Everything* about the batches, i.e. recipe, water, process, mash, aeration, etc were identical up until the point yeast (US-05) was pitched. Both were pitched at 64 degrees. Then I temp-controlled my beer, and he took his home to ferment w/o control. Mine fermented at 64 degrees, with a controlled rise to 72 at the very tail end of ferment to finish it off. His climbed up for about a day or so to the 76-78 degree range in the early active fermentation stages before subsiding and coming back down naturally.

We submitted both to a homebrew club meeting for evaluation, including a couple members who are BJCP judges. The results were clear. The temp controlled beer had comments like "good malt and hop balance", "clean crisp bitterness", "great mouthfeel", "great hop flavor". The un-controlled beer was still decent, but with some comments like "very strong grapefruit flavor", "not well balanced", "slightly solventy, little medicinal in the finish", "finish leaves something to be desired".

The temp-controlled beer got judge scores of 40/39/36. The non-controlled (same judges/same order) got scores of 29/32/25. So the scoring ranged from 7 to 11 points difference between temp-control and no control.

So what's the takeaway?

A beer in the 40/39/36 range will commonly medal in competition. A beer in the 29/32/25 range will not. The temp-controlled beer was a very nice beer. The non-controlled beer wasn't *bad*, but it wasn't good enough to stand alongside a commercial DIPA.

All the brewday factors were identical, but we were left with two very different beers. If you want your beer to score like the first one, you absolutely need fermentation temp control.

I agree 100%, Also:

The earlier in the fermentation cycle the wort is, the more crucial the control needed.

Ambient temp in your cellar does not equal the temp in the fermenter.

I agree.. Temp control is one of the best things you can do to make good beer. Also pitching the proper amount of healthy yeast is right up there too. Do those things and you brews will be good.

Water is wet? Certainly a sentiment worth reiterating. I'll also something that often gets overlooked, especially by novice brewers.

When people speak about fermentation temperatures, they are talking about the wort, not the ambient air temp. The two are not the same and the wort temp will ALWAYS be higher than the ambient air during active fermentation. The higher the intensity of fermentation the greater the differential in temperature between wort and ambient air.


My top 3 factors would be

Ferm/pitching Temps
Dissolved O2 levels
Yeast cells pitched

This all boils down to one thing, providing the best possible work environment for yeast

If you aren't doing this you may as well not pay attention to the other aspects of brewing, because it's all just window dressing compared to this cornerstone.

Playing devil's advocate a little here but...

There is a ton of really good beer made without strict temperature control. Three of the best beverages I have ever produced were fermented in a carboy in the corner of a spare closet at ambient temps. All three have brought home numerous medals in multiple competitions. They have scored between 37 and 42 in all three cases. Sometimes I just run out of temp controlled fermentation space so I do what I must.

Now that is not to say things are completely left to chance. I do make sure my beer is at fermentation temperature before I pitch yeast. My yeast is also at fermentation temperature before I pitch it as well. While my temp may not be strictly controlled it is held fairly constant without wild swings in temperature.

I think more harm comes from stressing yeast with wild temp swings than simply allowing a beer to ferment at 70 degrees instead of 66 degrees. I think style also comes into play here as well. If I brew a porter or stout and a pale ale on the same day but only have room for one in the ferm fridge you can bet the pale ale is going in the fridge.

+1000 to the thread starter. Truer brewing words of wisdom have never been spoken.

Yep!

I tell every new home brewer that temp control is the single best investment I made in home brewing equipment and I stand by that.

MidTNJasonF said:

Playing devil's advocate a little here but...

Now that is not to say things are completely left to chance. I do make sure my beer is at fermentation temperature before I pitch yeast. My yeast is also at fermentation temperature before I pitch it as well. While my temp may not be strictly controlled it is held fairly constant without wild swings in temperature.

Click to expand...

Appreciate the devil's advocate position...

I'm not saying you need +/- 1 degree F with a temp controller and refrigerator, but that temps -- particularly early in fermentation -- need to be monitored and steps should be taken with most ale yeasts to keep them at 70 or lower. For most ales I think they'll be better at mid-low 60's than even up at 70 [I basically never ferment above 68, with most in the 62-65 range], but I think every degree you creep above 70 is just inviting problems.

HOW temp control is accomplished is a lot less important than just making sure the temps aren't allowed to go nuts. Depending where you live, how your house ambient temps behave, and what time of year it is, it might not require much active "control". But not everyone has the luxury of a basement or cellar where ambient temps sit at a nice constant 60 degrees

TEMP CONTROL IS NOT AMBIENT TEMP

You can put stout in early fermentation at 75F in a chest freezer SET TO ZERO and that effer will not cool down 1 degree until it is WAY too late.

Temp control = Proper Chilling

cheezydemon3 said:

TEMP CONTROL IS NOT AMBIENT TEMP

Click to expand...

Agree completely. I was specifically referring to wort temps, not ambient. For the beer I fermented, temps were taken using a Johnson controller inserted into a thermowell into the center of my fermenter. For the other brewer, it was measured with a fermometer on the side of his carboy.

It's my belief that it's dangerous to allow wort temp for most ales to exceed 70 degrees during active fermentation, and even that is higher than I personally allow my beers to go during active stages (though at the very end of the ferment, I often allow it to rise to 72 to finish off).

Fermentation temps and controlling them are key to making great beer....no doubt. What I don't think gets explained nearly enough though to new brewers is exactly what this means. I have heard that Budweiser maintains temps to within .1 degree F. during fermentation. Not 1 degree but .1 degree!! Now that is not really within our reach as homebrewers but how much temperature fluctuation is too much? If you are measuring your temps via a thermowell you could easily have a 2-3 degree swing multiple times during fermentation depending on the type of controller you are using.

Phunhog said:

I have heard that Budweiser maintains temps to within .1 degree F. during fermentation. Not 1 degree but .1 degree!! Now that is not really within our reach as homebrewers but how much temperature fluctuation is too much? If you are measuring your temps via a thermowell you could easily have a 2-3 degree swing multiple times during fermentation depending on the type of controller you are using.

Click to expand...

Very interesting point. The question is whether the 2-3 degree swing a typical homebrewer might see (i.e. I set my controller to a 1-degree swing, but I'll bet the actual value is >2 degrees) is more impactful to *quality* or to *repeatability*?

I'm guessing that for Budweiser, the need to make that beer taste the same every time requires even tighter control than most homebrewers are capable of providing. But does a beer that has 0.1 degree swing taste *better* than a beer that has a 2.5 degree swing? Or do they taste equally *good* as long as the yeast are kept well within their comfort zone?

I know I'll probably never have good enough of a process control that 0.1 degree would be meaningful for me for repeatability. But if a 2.5 degree swing is enough to stress out the yeast and impact the quality of beer, I wonder how important it might be to investigate a way to tighten that up? I *am* an electrical engineer... It can't be that hard

This thread is full of win. As the Pope, JZ, put it--fermentation is 80% or more of beer character.

I've come to believe that making wort is the easy part. It's pretty easy to follow a recipe, weigh out the grains, hit the mash temp (being off by a few degrees doesn't make nearly as big a difference at this stage), add the right amount of hops at the right time... that stuff is all child's play.

It's the yeast that really make the difference. You need to pitch the right amount of healthy yeast, at the right temperature, into a well-aerated wort. It's a little paradoxical that these are simultaneously the most important factors, and yet also the hardest to control and measure.

If I have a 2L starter on a stir plate, how much yeast is that? Is that 250 billion? 350?

If I splash my wort while transferring into the fermenter, how many ppm of O2 is that? What if I agitate it with a Fizz-X de-gassing rod on a drill for a minute or two? Will that get me to 8 ppm? Or just 2 ppm?

If my wort is fermenting in a room with an ambient temperature of 70° F, what temp is my wort? What if I sit in in a pail of water? Now what's the temp deep inside that fermenter? What if I throw a couple frozen apple juice bottles into the tub? Now what's my temperature?

These things are the hardest to measure, but they have the biggest impact on the resulting beer.

I just started getting into temperature control. I'm still using water baths, but in the winter I used aquarium heaters and my stir plate to heat the water bath up and maintain a consistent temperature. Now that my basement is around 70F, I use the water bath and stir plate, but I thought I was going to have to use ice bottles, but I've positioned a fan above and it's keeping it right around 66-67F, which is right in the middle of the range for WLP090, so I think I'm doing okay.

My question is about the temperature ramps. I see a lot of people do them, but I'm not sure where to start to figure out how to do it. Seems like a lot of people start ramping up towards the end of fermentation, but what does that exactly mean? When do you start it, when do you end it and at what rate? And how do you know what temperatures to use? The WLP090 I used has a range of 65-68F. Should I go above that at the end of fermentation? What if I use Wyeast 1056, which is good up to 72F? Should I go up to the end of the listed temperature range?

Thanks for any help you can provide.

bwarbiany said:

I wonder how important it might be to investigate a way to tighten that up? I *am* an electrical engineer... It can't be that hard

Click to expand...

Fellow EE chiming in...

I built a Son of Fermentation chiller(google it) and rigged it for heating as well. I assembled a controller with SSR's and mechanical relays that control the fans and heater(high-temp painted lightbulb in galvanized ducting). I used a LM86 temp controller chip that utilizes a diode-connected 2N3904 as the temp sensor. The micro is an Atmel ATMEGA8 and have a blue LED backlit 2x16 character display(HD44780 controller). I can calibrate the sensor using offsets programmed into the LM86 or my firmware. The sensor is wrapped in grounded foil and I tape it to the carboy during fermentation. I've floated thermometers in the primary and it's dead-nuts accurate in terms of regulation, ± half a degree F. It's ugly, but it works and it's original!

I control within .1° C using an STC-1000 and what I call ‘creative use of overshoot’. I ferment in a water bath, so my methods don’t directly apply to air, but I think the principle is the same.

Consider these two cases:

1. Probe in air
Pro: frequent small cycles, good regulation
Con: weakly correlated to fermentation heat

2. Probe in Thermowell
Pro: Strongly correlated to fermentation heat
Con: long cycles, big temperature swings

How ‘bout we split the difference? Place the probe on the side of the fermentor with some insulation under it. Experiment until you get the duty cycle you want.

As the compressor runs, the probe cools and shuts off the compressor. Since it’s attached to the fermentor, conduction will heat it up and initiate another cycle. Shorter cycles, better regulation.

bwarbiany said:

HOW temp control is accomplished is a lot less important than just making sure the temps aren't allowed to go nuts. Depending where you live, how your house ambient temps behave, and what time of year it is, it might not require much active "control". But not everyone has the luxury of a basement or cellar where ambient temps sit at a nice constant 60 degrees

Click to expand...

THIS makes me glad that as a novice brewer I have a basement that sits in the low 60s (I know, I know NOT ferm temp). I may not have a stove that can boil more than 2 gallons of water, but I can consistently ferment in the high 60s at most. Much easier to boil on a banjo in the garage and make my own wort chiller than convert a freezer.

Now do I build a ferm chamber first, or a conveyor to get the 70lb kettle of wort from my kitchen out to the garage and back. . . .

Wynne-R said:

How ‘bout we split the difference? Place the probe on the side of the fermentor with some insulation under it. Experiment until you get the duty cycle you want.

As the compressor runs, the probe cools and shuts off the compressor. Since it’s attached to the fermentor, conduction will heat it up and initiate another cycle. Shorter cycles, better regulation.

Click to expand...

That's precisely how I use mine. Sensor is covered in foil for better thermal conductivity and taped on the carboy with duct tape. I've found that 1 minute of hysteresis keeps it locked in temperature wise. The insulated box keeps it from cycling so much.

Do those STC-1000 units operate two-stage or only heating or cooling? It would be nice to have a backup unit, I'm not wire-wrapping another one of my boards!

I know I am being redundant, but I see people missing the boat.

I WOULD TAKE A BREW CHILLED TO 60F and LEFT TO 75F SUMMER TEMPS

OVER

A WORT CHILLED TO 75F AND THEN SUBJECTED TO A ZERO DEGREE FARENHEIT FERMENTATION CHAMBER

cheezydemon3 said:

I know I am being redundant, but I see people missing the boat.

I WOULD TAKE A BREW CHILLED TO 60F and LEFT TO 75F SUMMER TEMPS

OVER

A WORT CHILLED TO 75F AND THEN SUBJECTED TO A ZERO DEGREE FARENHEIT FERMENTATION CHAMBER

Click to expand...

For sure. I do make sure my wort is chilled to my desired pitching temp first, before I pitch yeast and before it goes in the chamber. I don't rely on my controller bringing the wort temp where I want it, just keeping it there afterwards.

i talk about 1028 a lot because it is probably my favorite yeast. fermented at 57-61 degrees it makes an awesome clean pale or IPA. but bump that up to 66 and suddenly you have a minerally beer with very little hop character.

I forgot to make enough ice for my IC pre-chiller beforehand on brewday, and frustratingly could only get my wort down to about 72*. Ambient house temp is 71-73* max, dropping a little lower at night, and when my clone of Bells 2 Hearted was fermenting, much to my dismay, the stick-on thermometer read 77* at peak activity.

I am a little worried about this beer...but, it is what it is, and I'll drink it one way or another.

The truly sad thing is...I have a fermentation chamber...a free fridge I got has been repurposed, complete with a 1-stage Johnson temp controller. Unfortunately it got gross over the wintertime since it never ran, so it needs a lot of cleaning. Plus I have 3-4 doors/frames stacked up against it due to some DIY home repairs...so not super accessible right now.

If i would have taken an hour or two to get it ready on brew day, all my troubles could have been solved...but alas, now I will have to suffer less optimal beer. This post is also a mental note to clean that thing out, ASAP!

So I just brewed my first beer on Saturday and its fermenting away happily in my keezer. I've already decided to focus on temperature control during fermentation as my primary focus for the next few brews.

The question I have regarding this is the following. Is it better to chill my wort a bit too far and pitch at a lower temp (say 62 F) and let it rise to the target temp (say 68 F) or pitch a slightly higher temp (73 F) and try to crash it down? In order to acheive the former, I'd probably have to buy an IC and run that through an ice bath before it enters my plate chiller (unless there is a better/cheaper method).

I used a plate chiller and my wort came out at 74 F and my fermentation temp was 68 F (ambient, another lesson learned). I aerated with an aquarium pump and an aeration stone for 15 minutes. Fermentation started about 4 hours after pitching [WY 1056] (quicker than I expected) and has slowed to a crawl as of this morning.

Thanks for the great discussion. I can't wait to improve my process for the next brew!

smizak said:

For sure. I do make sure my wort is chilled to my desired pitching temp first, before I pitch yeast and before it goes in the chamber. I don't rely on my controller bringing the wort temp where I want it, just keeping it there afterwards.

Click to expand...

I do believe that most of the brewers who understand the importance of temperature in the fermentation process to the point where they take the sort of steps we are talking about here are also careful to pitch at or a few degrees below the starting ferment temp.

cheezydemon3 said:

I know I am being redundant, but I see people missing the boat.

I WOULD TAKE A BREW CHILLED TO 60F and LEFT TO 75F SUMMER TEMPS

OVER

A WORT CHILLED TO 75F AND THEN SUBJECTED TO A ZERO DEGREE FARENHEIT FERMENTATION CHAMBER

Click to expand...

LowNotes said:

I forgot to make enough ice for my IC pre-chiller beforehand on brewday, and frustratingly could only get my wort down to about 72*. Ambient house temp is 71-73* max, dropping a little lower at night, and when my clone of Bells 2 Hearted was fermenting, much to my dismay, the stick-on thermometer read 77* at peak activity.

I am a little worried about this beer...but, it is what it is, and I'll drink it one way or another.

The truly sad thing is...I have a fermentation chamber...a free fridge I got has been repurposed, complete with a 1-stage Johnson temp controller. Unfortunately it got gross over the wintertime since it never ran, so it needs a lot of cleaning. Plus I have 3-4 doors/frames stacked up against it due to some DIY home repairs...so not super accessible right now.

If i would have taken an hour or two to get it ready on brew day, all my troubles could have been solved...but alas, now I will have to suffer less optimal beer. This post is also a mental note to clean that thing out, ASAP!

Click to expand...

Not sure if this is what you are saying, but if you think that the fermentation chamber would have helped at all without more ice, see above.

Yes the STC-1000 is dual stage. If I set it to 17° C, then the cold relay kicks on at 17.3 and the warm at 16.7. assuming the differential is set to the .3° C minimum. In either case it kicks off at 17.0.

Not sure what you mean by one minute hysteresis. Is that the compressor run time?

The foil sounds like a slick idea. I was thinking of a few layers of tape between the sensor and the fermentor, but that might not be enough.

cheezydemon3 said:

I know I am being redundant, but I see people missing the boat.

I WOULD TAKE A BREW CHILLED TO 60F and LEFT TO 75F SUMMER TEMPS

OVER

A WORT CHILLED TO 75F AND THEN SUBJECTED TO A ZERO DEGREE FARENHEIT FERMENTATION CHAMBER

Click to expand...

I'm not saying I disagree (I generally try to pitch yeast 2-4 degrees below optimal ferment temps and let it rise to ferment temp from there). I definitely DO NOT recommend pitching hot. My personal belief is that many of the off flavors are generated in the early yeast reproductive phase, and that this is thus the MOST critical time at which to avoid high temps.

But for the purposes of this experiment, we controlled for this. We pitched yeast for both beers into 64 degree wort. His then rose to the 76-78 temp naturally, i.e. it wasn't purposefully heated, and you can see from the judges' comments what it did to the beer.

malaeum said:

The question I have regarding this is the following. Is it better to chill my wort a bit too far and pitch at a lower temp (say 62 F) and let it rise to the target temp (say 68 F) or pitch a slightly higher temp (73 F) and try to crash it down? In order to acheive the former, I'd probably have to buy an IC and run that through an ice bath before it enters my plate chiller (unless there is a better/cheaper method).

I used a plate chiller and my wort came out at 74 F and my fermentation temp was 68 F (ambient, another lesson learned). I aerated with an aquarium pump and an aeration stone for 15 minutes. Fermentation started about 4 hours after pitching [WY 1056] (quicker than I expected) and has slowed to a crawl as of this morning.

Click to expand...

Yes, it's better to pitch low and let it rise. (IMHO)

Instead of dropping coin on an IC, why not just put the 74 degree wort into your keezer, let it come down to mid-60's, and *then* pitch yeast. It should only take a few hours to chill down to that level, and you're not really missing anything by waiting only a few hours. In cases where I haven't bought ice for my CFC and the beer has gone into the fermenter too hot, I've left in the fermentation chamber as long as overnight before pitching yeast, with no ill effects. A lot cheaper than buying an IC when you already have a plate chiller!

Down the road, if you go with a multi-pump system, you can probably do something similar to what I do for chilling:

1) Recirculate worth through the CFC back into the boil kettle using pump #1 while running hose water through the CFC until the kettle temperature is below ~120 degrees F.
2) Start recirculating ice water through the CFC using pump #2.
3) Move outflow of CFC to the fermenter and control temp of what's going into the fermenter using the valve on pump #1 to control outlet flow/temperature.

Either way, if you already have a plate chiller, it's silly to spend money on an IC now when future equipment purchases will probably make the IC obsolete.

Wynne-R said:

Not sure what you mean by one minute hysteresis. Is that the compressor run time?

Click to expand...

I mean that the temperature has to be solid over or under the set temperature for one minute before either stage kicks on. Stops it from cycling too much. You could call it duty cycle too. The one minute seems to keep it dead-on, a good compromise between outside air influence and real fermenting wort temperature.

I leave my wort to chill overnight too. I put the controller about three degrees higher then my target. Usually its in target when everything averages inside the chest freezer.

Decent Water filter and temp. Control are the major factors from my old decent rating to world class beer rating.

This is a good topic that many homebrewers that I've met fail to appreciate, and its something that I see everyday on these forums. There are tons of threads on here of people agonizing over mash pH, ounces of specialty grains, putting together a delicate yet sophisticated hop schedule, but who choose to ferment at the ambient temperatures in their homes. There are likely a very small minority of people here who have a space in their home that maintains a constant ambient temperature suitable for each specific strain of yeast throughout the year, but most of our homes experience wide temperature swings throughout the day and night. Temperature control during fermentation is easily the most important factor of what goes into making a great beer, followed by yeast starters for liquid yeast, and aeration. Agonizing over the details while ignoring the major components of brewing great beer is something that I see a lot of here and in person.

I sincerely wish someone had emphasized the importance of temperature control to me when I first started brewing. Like many, I started out with a kit during Christmas and produced a drinkable beer. When I tried to brew in the summer I made beer that was atrocious and had to be dumped. It was incredibly discouraging and almost convinced me to leave the hobby before I gave temperature control a serious attempt. A water bath/swamp cooler can work but a chest freezer with a temperature controller on it is the way to go IMO. Nothing will impact the quality and consistency of your beer like temperature control. There is a thread on here with a guy who is making a 3 BBL brewery out of his house. He has shiny equipment. He does not have temperature control - without trying his beer, I would say politely that he's likely not making the best beer he's capable of.

Some people will be stubborn and insist that their ambient temperatures are sufficient. That's fine. I'll keep hanging ribbons up on my wall and have my friends brag about my beer to strangers (to my embarrassment) with my temperature controlled beer.

bwarbiany said:

Instead of dropping coin on an IC, why not just put the 74 degree wort into your keezer, let it come down to mid-60's, and *then* pitch yeast. It should only take a few hours to chill down to that level, and you're not really missing anything by waiting only a few hours. In cases where I haven't bought ice for my CFC and the beer has gone into the fermenter too hot, I've left in the fermentation chamber as long as overnight before pitching yeast, with no ill effects. A lot cheaper than buying an IC when you already have a plate chiller!

Click to expand...

I suppose I was worried about some sort of infection. I figured if I get the yeast in there in short order it dominates any nasties picked up from the air but if I gave them time in that sweet environment they might take off before I pitch. I believe I value sanitation highly and with your advice it sounds like I am just being a bit overly cautious. Glad to hear that this would work as I really didn't want to spring for an IC after I just invested in a plate chiller (HOLY HELL do those things work SO much better than ICs).

I've brewed about a dozen batches with my old roommate and we always fermented in ambient temperatures. I'm ready to step it up to produce much better beers now that I am able to have my own equipment. Thanks very much for the advice!

Probably a stupid question but recently got an old fridge to ferment in... I want to get a Johnson temp controller, what's the best way to handle the probe? Is there a way to get it directly into the wort? I use plastic buckets & better bottles

Larzean said:

Probably a stupid question but recently got an old fridge to ferment in... I want to get a Johnson temp controller, what's the best way to handle the probe? Is there a way to get it directly into the wort? I use plastic buckets & better bottles

Click to expand...

Save your money. Get an STC-1000. I use three and they're excellent. Since you're in NY, you may also want the ability to run a small heater inside the fridge. The STC-1000 is a dual controller and will handle that just fine.

Simply tape the sensor to the outside of the bucket/BB. Tape a few layers of some kind of insulation (I use bubble wrap) over top of it. It will read the bucket temp which is only about 1*F cooler than the liquid sitting in the very middle of the bucket at the most active phase of fermentation (based on posts of folks who measured temps in both places at the same time).

Larzean said:

Probably a stupid question but recently got an old fridge to ferment in... I want to get a Johnson temp controller, what's the best way to handle the probe? Is there a way to get it directly into the wort? I use plastic buckets & better bottles

Click to expand...

"Best" method? In my opinion, it's a thermowell.

But before I had a setup that allowed for that, I would duct tape it to the side of the fermenter with a bunch of paper towels to insulate it from the fridge temps so I know it would be registering beer temp. Worked fine.

Bwarbiany, really?

You wondered aloud about the possible need for tighter regulation.

I suggested a possible solution and explained how it might work.

Smizak apparently uses a similar method and gets ± .5°F.

Then you endorse the thermowell method, the largest possible temperature swing for a given controller.

https://www.homebrewtalk.com/f14/ye...ally-important-417013/index2.html#post5283920

Wynne-R said:

Bwarbiany, really?

You wondered aloud about the possible need for tighter regulation.

I suggested a possible solution and explained how it might work.

Smizak apparently uses a similar method and gets ± .5°F.

Then you endorse the thermowell method, the largest possible temperature swing for a given controller.

https://www.homebrewtalk.com/f14/ye...ally-important-417013/index2.html#post5283920

Click to expand...

I maintain that a thermowell is the most accurate way of measuring the wort temperature.

I would also think that the method you're referring to is more applicable to your fermentation in a water bath than for those of us fermenting in air in a fridge.

The specific heat of water [or wort] is SIGNIFICANTLY higher than the specific heat of air, so IMHO the overshoot of allowing the air around a fermenter to get quite a lot cooler than the wort would be significantly less impactful than allowing the water bath to get even a degree or two cooler than the wort. I just don't think the wort temp overshoot will be all that big of an issue from air temp overshoot.

I think my main issue if I wanted to reduce swings is that my current temp controller (Johnson) has a 1 degree resolution. Reducing that to 0.3 resolution with an STC-1000 (or similar) would be enough for me to be happy, and I think I could do that just as well with a thermowell (and not overtax my compressor) as I would get with your creative use of overshoot.

Thanks for the input guys