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How do you accurately monitor fermentation temperature?

I would like to hear about ways to accurately monitor the temperature of the wort during fermentation. I don’t have a very sophisticated brewing system–no fermentation chambers, etc.-- and my house swings between a little too hot/cold, so what is the best way to figure out just how warm it is inside the carboy? Is the temperature strip stuck on the outside of the carboy giving me an accurate measurement of what’s going on inside, or is it muddled by the ambient temperature of the room that it’s in? Any and all help is appreciated, thanks!

stick on thermometers are pretty accurate.

I use the swamp cooler method of temp control. I recently fermented a ‘faux’ Kolsch (using s-05) and targeted a temp of around 55*. I put the carboy (6 gal carboy, 5 gal batch) in my laundry sink, fill sink with water up to beer level, then add frozen water bottles. Kept the water near 54-55* by swapping bottles every 8-10 hours as needed. Sporadically checked beer temp by dipping sanitized thermometer into beer. Temp of beer (even at high krausen) was never more than one degree above water temp, and was usually exactly the same. So I’m convinced that by monitoring the water temp, I’m monitoring my beer temp fairly accurately. I’ve used this cooler method dozens of time and have always had good fermentations and no fusels!

If you don’t have a big laundry sink, you can get a big, cheap plastic tub at walmart to use. Just make sure it’s deep and wide enough to do the job.
Hope this helps.

Cheers,

Ron

While the swamp cooler method above does work relatively well for controlling fermentation temps, I personally don’t advise opening up your fermenter to dip in a sanitized thermometer. It is time consuming and unnecesarily exposes your beer to the environment (oxygen and infection).

A stick on thermometer is a couple bucks.

+1 to a large, insulated water bath. Yep, don’t measure the actual wort temperature. It isn’t worth risking infection.

Chest Freezer with a brewpad on the inside. Single stage temp controller, plugged in to freezer for early on in the ferment, then plugged into the brewpad (heat) for the end to ensure it stays warm. Temp probe taped and insulated with styrofoam taped to the outside of typically plastic buckets. Single best investment ($120 total, got the freezer cheap) I have made in making better beer.

I’ve seen rubber stoppers online that you can slide a long temperature probe way down into the middle of the fermentation vessel. That’d give you a really good idea of your internal fermentation temp.

The stickers just seem so much easier to me though. I tape my temperature probe to the side of the carboy and put some thick bubble wrap on top of that to keep it from getting the direct cold/hot from the ambient air (or side of the freezer/heat source). I think it’s close enough.

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Yep. I use about a dozen of them and they’re always within 1 degree of a thermometer.

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Or 5 Euros where I am… :frowning:

Even on plastic fermentation buckets? …or just glass carboys?

On anything with a thin wall and isn’t insulated (won’t work on a cooler). But yes, good for buckets or carboys.

Yeah, wasn’t perfectly clear about this. It was just a one time experiment. I definitely would not advise doing this. Was just trying to show that by checking the water temp in the swamp cooler, you can get an accurate assessment of the temp of the beer. I just keep a thermometer near the laundry sink and check the water temp every so often. When I used to use the stick ons, they would get wet and go bad. This is my way of avoiding that, since I don’t yet have a ferm chamber-which seems to me to be the best option if you can do it.

:cheers:

Ron

I only use buckets and they work great.

Awesome feedback! Thank you, everyone!

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