Best way to determine temp of beer in opaque food-grade bucket?

[brewer1222]

What's the best way to figure out what temperature my beer is inside my food-grade bucket? I guess I could take the lid off and stick a thermometer in but I'd rather not do that.

 

[demonrichie]

how are you controlling temperature? you could use the ambient temp as fermenting wort usually rises 5-10 degrees over ambient temp

 

[brewer1222]

Right now it's in a bathtub with the fan running.

 

[arturo7]

Maybe something like this?

http://www.austinhomebrew.com/product_info.php?products_id=998

 

[demonrichie]

people on here told me to keep my swamp cooler about 5 to 10 under my desired fermentation temperature and its worked for me well

 

[brewer1222]

That works through the plastic?

 

[remilard]

Best? A stainless thermowell through the stopper. This will run you about $15 and assumes that you have an RTD or thermistor that will fit inside of it. Also assumes you have a stopper and are willing and capable to drill a second hole through it.

http://www.brewershardware.com/Straight-Wall-Thermowells/

Barring that, I wouldn't go sticking stuff in there. The water bath and some assumption about the temp of the beer vs the water is probably the best.

 

[Olddog]

Maybe something like this?

http://www.austinhomebrew.com/product_info.php?products_id=998

That's what I use for my bucket fermenter.

 

[Boondoggie]

That works through the plastic?

Yes it does, and is accurate enough for these purposes.

 

[dndlyon]

I'm posting because I'm wondering if I'm missing something. Can you get an accurate enough temperature by placing a thermometer on top of the bucket? I know this is ambient air temp, and the fermentation adds some heat to the liquid in the bucket, but isn't the ambient air "good enough"? (yikes! I hope so, because if not, then I'm not monitoring my temp close enough!)

 

[Hang Glider]

Well, if your ambient air is 60F, then you're probably good. If your ambient air is 70, your beer is fermenting at between 74 and 80, which is quite a bit warm for ale yeasts.

If it's sitting in a water bath that is significantly cooler than ambient air, you're in better shape. WallyWorld sells an indoor/outdoor thermometer with a remote bulb made to sit outside. Drop that bulb into the tub of water and you've got a decent idea of the fermenting temps. Water will also extract some of the heat of fermentation better than air, so the water temp and fermentation temp will be closer than the typical 4-8 degree rise.

 

[HairyDogBrewing]

I use this:

I epoxied on a bit of copper tubing and added an extra grommet to the lid.
The hardest part is finding a thermometer with an 8 inch probe.
These thermometers are POS.

BTW I usually see only 2 or 3 degrees above ambient temperature.
I'm sure it depends on the yeast, recipe, etc.

 

[Marko73]

I myself focus as much as I can on the ambient temp. The temperature is higher during the active fermentation phase, but then isn't so drastic as it settles in over the weeks. I guess I have always found the ambient temp easier to control and easier to measure.

Not sure if this helps, just my $.02

 

[Yooper]

I'm posting because I'm wondering if I'm missing something. Can you get an accurate enough temperature by placing a thermometer on top of the bucket? I know this is ambient air temp, and the fermentation adds some heat to the liquid in the bucket, but isn't the ambient air "good enough"? (yikes! I hope so, because if not, then I'm not monitoring my temp close enough!)

In my opinion, no. Ambient air may be the same temperature as the beer, or 10 degrees lower.

Those cheap "stick on" thermometers work well enough, though. You can gauge the temperature within a degree or two. Another way to check the temperature is to keep the fermenter in a water bath. (I use a cooler, and add water to the level of the beer). I float a thermometer in the water, and it's a pretty good gauge of the beer temperature too. If it's too warm, I just add a frozen water bottle.

 

[Revvy]

I'm posting because I'm wondering if I'm missing something. Can you get an accurate enough temperature by placing a thermometer on top of the bucket? I know this is ambient air temp, and the fermentation adds some heat to the liquid in the bucket, but isn't the ambient air "good enough"? (yikes! I hope so, because if not, then I'm not monitoring my temp close enough!)

Most of use your thermometer strips on the side of the bucket, about midway up. If you are using a swamp cooler, than above the water line. And yes, it works "good enough" for our needs.

You can also add an aquarium thermometer to your swamp cooler, and pretty much after a couple days all the liquid should be close enough in equilibrium temp wise, unless you are adding ice, that it will give you an good enough idea.

You have to realize, that although we stress temp control and keeping the ferm temp in the ideal range of the yeast. We aren't talking needing minute by minute precise temp monitor, with triple back up and feedback loops. This isn't a nuclear reactor core.

And your beer isn't going to go "off" if you don't know exactly the core temp at any given time. Or if you look at it finny. It's going to be beer, and probably good beer, no matter whether have a accurate temp reading or not.

Beer was brewed successfully long before ss steel glycol cooled fermenters, and will be brewed long after the zombies eat our brains and the "King of the sacred barley water" trades slave girls for drinkable liquid.

Just having a basic awareness is fine. "Hey my apartment gets in the 80's in the afternoon, so I guess I need to rig up a swamp cooler for the first few days." And then rigging one up is going to be enough to be the difference between making great beer and making good beer.

Back in the old days they brewed seasonally, using more heat tolerant yeasts in the warmer times of year, or they just fermented in a cave, or a cellar.

This isn't a newborn baby, so we don't need to be uber anal about the temp every second. Looking at a strip and saying "hey it's fermenting around 63 degrees" is going to make just as good a beer than knowing that the beer is 63.8 degrees near the wall of the bucket and 64 degrees at the core.

 

[brewer1222]

thanks for the tips, guys, these are great

 

[mk78]

I'm kinda bummed I'm gonna miss out on the slave girls after zombies eat my brain.

 

[shelly_belly]

I have a 5.5 gal Kolsch in the freezer with a ranco thermistor taped to the middle of the BetterBottle. The ranco is set on 63F+-1. A stick-on thermometer reads 65F. A thermometer in the freezer reads 60 now 10 days in. At 4 days in the "ambient" thermometer reached a low of 56F. Thus, at high krausen with a 65F target, a 9 degree swing between ambient and actual temp. Ranco thermister and stick-on thermometer read constant the whole time.

Enjoy!