Accuracy of the stick on thermometers

The fermometers that you stick on your carboy. How accurate are they? They read the temp of the fermenting beer right? Not the ambient temp of the room. Guess I have just never really thought about it before.

I have found them to be fairly accurate as long as there is not a big difference between the ambient vs beer temperature. They are influenced by ambient as one would guess.

Good to see ya around again, Greg!

I have found the stick on thermometers to be within 1-2F of the actual interior temp.

You have to be careful not to soak them in a tub of water when you are washing or sanitizing a bucket or carboy. They will tolerate a dip or rinse, but not a soaking

So they are pretty close. I guess that is good to know, I’ve never thought to actually test them. That said right now our fermentation chamber (aka: “the basement”) is around 73* and I’m trying to stick around 65* for an ale with frozen water bottles and a swamp cooler so we’ll see how it goes. It’s been way to hot this year…

So, if possible, put the stick on above the coolant line (swamp water) and below the top of the beer

Agreed that they’re pretty accurate… at least within a degree or two. I recently found out my thermometer was off by 7 degrees. When I filled the fermentor from my kettle, I saw a 7 degree difference. I assumed it was the stick on fermometer, but after checking against two other thermometers, the stick on fermometer was accurate and my original thermometer was off.

[quote=“Denny”]Good to see ya around again, Greg!

I have found the stick on thermometers to be within 1-2F of the actual interior temp.[/quote]They blocked us at work but now we can get here during lunch. Been travelling a lot too. Hard to do much from my iPhone when on the road.