Best Way to Measure Fermentation Temperature

[Bassman]

I have 2 fermentors, one is a carboy and the other is a plastic bucket. What is the most accurate, but relatively easy, way to monitor the temperature of the beer as it is fermenting? I currently have my bucket in a tub with water and a towel and fan arrangement to fight the heat but I am flying blind as to the actual fermentation temperature. The bucket has the plastic thermometer strip on it but it is wrapped by the wet towel and when I remove the towel to look at it several of the numbers are lighter, and not just numbers next to each other. I wonder if I destroyed the strip somehow. I think I read that the strips are not very accurate in terms of the actual wort/beer temperature.

Any thoughts? This will impact how I deal with temperature control in the future because, i.e. SOFC vs. Mini-fridge vs. Low-tech Lagering.

 

[Zooom101]

If the fermenter is more than 50% submerged in the water bath than you can assume that the temperature of the wort is roughly equal to the temperature of the water bath. I have found the fermentometer strips to be fairly accurate. I say this because I run a fermentation chamber with a temp probe taped to the side of a bucket and insulated with a few layers of towel. My temp controller always reads what the strip says.

You're ultimately going to want to build a fermentation chamber. It makes life much easier. Until then, I would get another strip. With the wet/towel and fan setup it is very difficult to control the temperature within ~2 degrees F. So you probably won't need much more accuracy than that. Mine says "fermentometer" on it and it works fine. If you're looking for even more accuracy, you can get an electronic thermometer with an wired probe and stick that to the side of your bucket/carboy.

My last piece of advice would be to get the "ebay temperature controller" that everyone is talking about in the DIY section of the forum. If you complete that build according to Androids instructions you could use it as an electronic thermometer and even use it to turn your fan on and off. That's probably as tight as your going to get with your temp control until you get a chamber. Plus, if you can use it to control your chamber when you eventually build it.

Good luck.

 

[mojotele]

I think I read that the strips are not very accurate in terms of the actual wort/beer temperature.

Mine are actually quite accurate. Usually if it reads, say, 66*F, I'll take the beer out for a hydrometer sample and find that it reads 67*F with my NIST traceable thermometer. The 1 degree difference can be explained by transferring to a warmer vessel.

 

[mc_eric]

If the fermenter is more than 50% submerged in the water bath than you can assume that the temperature of the wort is roughly equal to the temperature of the water bath. I have found the fermentometer strips to be fairly accurate. I say this because I run a fermentation chamber with a temp probe taped to the side of a bucket and insulated with a few layers of towel. My temp controller always reads what the strip says.

+1 to this. I've found those strips to be fairly accurate as well.

Also, the water won't ruin the strip, it just makes it hard to read when it's submerged. Once it dries off it will be fine. I've been using a water bath to control ferm temps, and my stick thermometer has been through many this many times, it still works fine. Just dont try to take it off once it's stuck on there. That will ruin it.