Question for the fermenter builders out there...

[MuddyCreek]

Those of you who do monitored fermentation temps in some kind of fermentation chamber, do you use a thermoprobe simply inside the chamber and attempt to adjust for the exothermic prediction of the fermenting wort, or do you rig a thermoprobe inside the fermenting bucket/vessel and maintain a more precise temperature through that?

(Again, if that doesn't make sense it's because other peoples' communication skills must be terrible. It makes perfect sense to ME!) ((Yes, that was a joke...))

 

[kickflip_mj]

I guess the question is how many ferementers are you going to have in one chamber? If it was one i would place the probe in the fermenter. But if its multiple I would just monitor the exothermic temps. you could get crazy and seperate the chambers and add maybe small computer fans to adjust temps?

 

[kh54s10]

I have not worked on getting a thermowell yet, but you want to control the temperature of the wort not the ambient. I tape the probe onto the outside of my fermenters (the newest one added to my chamber that will hold 3) and cover it with a folded washcloth to insulate it from measuring ambient.

You definitely do not want to just dangle the probe in the chamber.

 

[MuddyCreek]

No, if I was going to do it I'd build a port into the fermenter. (In this case I'd likely use plastic buckets.) I thought about doing a single vessel container but Huaco's multi-temp fermenter build got me thinking.

The trick will be figuring out how to get a clean, leak-proof port into the plastic that I can insert the probe through. I'm also trying to figure out the most cost-effective cooling system. Any suggestions for leads to build threads I haven't seen are appreciated.

 

[Felixio]

Another option I hear on the forums a lot is putting it into a small bottle of water/sanitizer, that way its reading does fluctuate with the air temp inside of the chamber, but still gives you a good idea of the temp of the liquid (beer) in the chamber.

 

[BreezyBrew]

I have done both; with a thermowell and with the probe taped to the side under bubble wrap which is air tight. It only took me one time to realize that a theromowell will completely overshoot the ambient temp in the fermentor. It takes a long time to cool the temp down in the middle of the worth so what ends up happening is the fermentor ends up dropping to about 40 degrees (if you are using a chest freezer). This negatively impacted my fermentation, because it put a portion of the yeast to sleep.

Now I just tape the probe to the side of the carboy and try to keep out as much air as possible. This becomes problematic since it's summertime and the wort will be cooler than the outside air, causing condensation on the outside of the carboy (If you are using glass). Tape doesn't really like this too much, it slides all over the place, so I have a couple of bungee cords wrapped around it as well. I would love for a product to be available to us of some sort that would attach to the carboy and not let the ambient air in, but right now, all we have is the bubble wrap. In a perfect world we would be able to monitor both, and have a blowoff tube. I have done a ton of research and this is what I have come up with.

 

[Monster Mash]

You want to control the ambient temp not the wort temp in a refrigerator, if you are using a glycol jacketed fermenter then you want to use a thermowell in the fermenter.

A refrigerator gets very cold very quickly, if you put the probe in the fermenter and set it for 65 degrees the ambient temp will drop down to 38 degrees and stay there until your fermenter hits 68, if you are using a freezer IT WILL DROP DOWN TO FREEZING!!. Then since the ambient is well below 68 your fermenter continues to cool while the ambient starts to warm. When your fermenter warms up 1 degree your refrigerator turns back on and cools down to 38 again until your fermenter hits the temp again starting the cycle all over.

When you keep the ambient at a set temp the fermenter might raise a couple degrees higher during high krausen so I usually set my temp a couple degrees cooler.

Put a thermometer on the side of your fermenter and insulate it so you can watch your ferm temp. Try both hanging the probe and taping the probe and you will see what I am talking about, it is worse for me because my fermenters are 30 gallons so the temp swings are huge, it won't be as bad for 5 gallons but it does happen.

 

[BreezyBrew]

Ambient temps will make the fermentor cycle more often than it has to.

 

[chemman14]

I have done both; with a thermowell and with the probe taped to the side under bubble wrap which is air tight. It only took me one time to realize that a theromowell will completely overshoot the ambient temp in the fermentor. It takes a long time to cool the temp down in the middle of the worth so what ends up happening is the fermentor ends up dropping to about 40 degrees (if you are using a chest freezer). This negatively impacted my fermentation, because it put a portion of the yeast to sleep.

Now I just tape the probe to the side of the carboy and try to keep out as much air as possible. This becomes problematic since it's summertime and the wort will be cooler than the outside air, causing condensation on the outside of the carboy (If you are using glass). Tape doesn't really like this too much, it slides all over the place, so I have a couple of bungee cords wrapped around it as well. I would love for a product to be available to us of some sort that would attach to the carboy and not let the ambient air in, but right now, all we have is the bubble wrap. In a perfect world we would be able to monitor both, and have a blowoff tube. I have done a ton of research and this is what I have come up with.

I use those carboy carriers (the ones made out of nylon straps) on all of my carboys. I just use the strap that goes around the carboy to secure my bubblewrap/probe combo.

 

[Monster Mash]

Ambient temps will make the fermentor cycle more often than it has to.

I've been doing it for 15 years, 10 years with the current fridge. It's better then having the ambient temp drop down below 38 degrees....

Just set the controller to have a 4 degree temp differential, the ambient air can swing 4 degrees without effecting the ferm temp because of the thermal mass of the fermenter.

 

[kh54s10]

You want to control the ambient temp not the wort temp in a refrigerator, if you are using a glycol jacketed fermenter then you want to use a thermowell in the fermenter.

A refrigerator gets very cold very quickly, if you put the probe in the fermenter and set it for 65 degrees the ambient temp will drop down to 38 degrees and stay there until your fermenter hits 68, if you are using a freezer IT WILL DROP DOWN TO FREEZING!!. Then since the ambient is well below 68 your fermenter continues to cool while the ambient starts to warm. When your fermenter warms up 1 degree your refrigerator turns back on and cools down to 38 again until your fermenter hits the temp again starting the cycle all over.

When you keep the ambient at a set temp the fermenter might raise a couple degrees higher during high krausen so I usually set my temp a couple degrees cooler.

Put a thermometer on the side of your fermenter and insulate it so you can watch your ferm temp. Try both hanging the probe and taping the probe and you will see what I am talking about, it is worse for me because my fermenters are 30 gallons so the temp swings are huge, it won't be as bad for 5 gallons but it does happen.

This sounds likely but does not happen for me.

I have a large plywood and foam insulation chamber that can hold 3 fermenters. When I put a new fermenter inside I have it chilled in the neighborhood of 68 degrees. I set the controller between 64 and 68 depending on the brew, with the probe insulated and taped to the side of the fermenter. I also have a thermometer and it will drop to somewhere 62-64. As the temperature of the wort stabilizes so does the ambient. As long as nothing freezes I want to control the temperature of my wort, not the air inside the chamber. The wort could easily go 5-10 degrees above ambient during fermentation.

 

[LandoLincoln]

I've just let the probe dangle in the air and I've also taped it to the sides of the glass carboy. Taping it to the sides seems to give the beer a more stable ferment. If I set it for 65°, then it stays there. For homebrewing purposes, I don't think a thermowell is all that necessary.

 

[MuddyCreek]

Well, it would certainly be easier to rig a probe to the outside of the ferment vessel. And I can see how you'd kind of be all over the map especially with lagers if you had the probe inside a vessel and wanted to chill it down to say 38 degrees. (Especially with 15 or more gallon fermenting vessels).

Good food for thought. I suppose if you were a total psycho you could have two probes prepared, one ambient and one inside the fermenter. You could use the ambient until you got the chamber to around 4 or 5 degrees below your target ferm temp for a day or so, then you could switch to the internal probe and get more exact temperature control without yo-yo'ing too much. That sounds like a bit of over-complicating though.

 

[funnycreature]

I use a wine cooler as fermentation chamber. It is by far not as well insulated as a fridge/freezer. I did immerse my probe in the first few inches of wort the past few times and it worked amazingly well. The "ambient" temp is a lot lower but because of the mediocre insulation the wort doesn't cool significantly after the compressor is turned off. The temp difference of my thermostat is set to 0.5 °C and that's about the biggest difference I've observed. Guess what I'm trying to say is that it will depend on your system whether you should hang the probe in the fermenter or the fermentation chamber.

 

[pfgonzo]

I have a different experience.

I use a refrigerator (not a chest freezer) for my fermentation chamber and have a thermowell inside the fermentor... bucking the trend of the above posts. Pic of the thermowell here: https://www.homebrewtalk.com/f51/speidel-fermenter-mod-388371/index2.html#post5080792

I feed the temp probe of my stc-1000 in the thermowell and read the central-wort fermentation temp. I also have one of those aquarium stickers on the outside of the fermentor. Unlike what people have posted here, I have not found the temperature differential between the two to be even remotely significant. My unscientific guess is that there is so much activity going on inside the fermentor (churning etc...) that it keeps the liquid temp relatively consistent throughout.

Now maybe I have a weak/slow fridge, and I certainly assume the carryover temperature drop from a chest freezer is more extreme (especially for batches larger than my 5ga ones), but I've never noticed more than a 1-1.5 degree differential from the probe and the sticker, and most of the time they match. This includes instances where my post boil chill can only get to 75-80 or so and I refrigerate it to 65 (or less) before pitching.

 

[chrisdb]

I use glycol through stainless coil immersed in the wort to cool, an external pad to heat. I have a thermowell into the middle of my conical that goes back to a 2 stage temp controller, but I also have a digital thermometer through the side of the conical to read the temp on the perimeter. I am ususally holding my temps down, and find the core temp is a few degrees colder than the perimeter. I try to compensate by averaging the diffence and resetting my temp controller so the 'average' of my two temps equals my target fermentation temp