Fermentation temp control questions

[marke14]

Hello,

I am relatively new to homebrewing - been at it for about a year now, still doing partial boil extract batches, moving to BIAB soon.

I recently purchased a kegerator and am for the moment using it as my fermentation temperature control chamber. I use a 6 gallon glass carboy for fermenting.

I have a separate thread going re: how to use the kegerator as both a kegerator and a fermentation temp control chamber; I will likely purchase a chest freezer as a dedicated temp control in the near future.

My question is: what temperature should I really be aiming for during fermentation? 65-70 F I know, but ...

For the current batch (just boiled yesterday), I am for the first time using a digital thermometer with a probe, which I sanitized and passed along the side of the rubber stopper/bung down into the carboy.

I've set the kegerator at 59 degrees F (it's a blonde ale fermenting in there at the moment), and the thermometer sticker on the side of the carboy shows a temp of about 62 degrees F. However, the probe has been holding steady at 77 degrees F. That is quite a big difference!

I've read/heard that those stick-on thermometers can be pretty inaccurate in terms of the actual average temp of the wort in the carboy as the sides and glass can be a bit cooler than the temp in the center of the liquid.

Should I be aiming for an internal temperature of 65-70 F, as measured by the probe inside the carboy?

In the future, assuming I have an Inkbird and chest freezer setup, would I do the same in terms of putting the Inkbird's probe into the wort/carboy itself, and then set the temp control to 65 (give or take, for ales)? Or do you guys fix the probe to the outside of the carboy, etc.

Last small Q - should I cut a small channel in the side of my rubber bung to accommodate the probe wire? Not sure how airtight it will be with the probe wire going along the side ...

Thanks in advance.

 

[kingmatt]

What temperature did you pitch? If you pitched warm and put it in the kegerator set at a lower temp, the yeast may have started fermenting before the wort had a chance to cool down.

Have you calibrated the temp probe to ensure it is reading correctly? I have found that those stick on thermometers are actually pretty accurate.

 

[marke14]

I calibrated during the specialty grain steeping, using a traditional liquid thermometer. I was surprised to see that among the 3 I was testing - a cheap analog dial 12" probe, the liquid, and the new digital one - the dial one was off by about +10 degrees F, and the liquid and digital ones were very close to one another.

I pitched at about 77 F from a yeast starter I had made. I have not previously tried to get the wort cooler than that as I only recently bought the kegerator.

Is the proper sequence, then, to use the immersion chiller to drop the temp as much & as quickly as possible (I use a closed-loop system with a submersible pump in a cooler filled with ice and water, but that only got me down to 77 F yesterday...), then store the wort in the chiller (kegerator or chest freezer) until you reach 65-70F, and then and only then, pitch?

There is currently a good deal of activity so fermentation is happening ... I already have some krauzen on top as well.

 

[kingmatt]

Is the proper sequence, then, to use the immersion chiller to drop the temp as much & as quickly as possible (I use a closed-loop system with a submersible pump in a cooler filled with ice and water, but that only got me down to 77 F yesterday...), then store the wort in the chiller (kegerator or chest freezer) until you reach 65-70F, and then and only then, pitch?

That is what I do in the summer when my groundwater won't allow me to chill below 80 degrees or so with my immersion chiller. As long as your sanitation is good, you can seal up your fermenter and put it in your chamber to chill overnight until you get to your pitching temp. If you pitched at 77 and the yeast started fermenting already, they are going to produce their own heat and it will be harder for you to get down to the proper temp.

I personally set my temp control to 4 or 5 degrees under my target fermentation temperature to account for the additional heat put out by the yeast orgy.

 

[marke14]

I personally set my temp control to 4 or 5 degrees under my target fermentation temperature to account for the additional heat put out by the yeast orgy.

Thanks for that. I will keep that in mind.

I dropped the kegerator temp down a bit and the probe is now showing 75 so I am making progress in the right direction. I don't want to make it too cold in there right?

 

[kingmatt]

Thanks for that. I will keep that in mind.

I dropped the kegerator temp down a bit and the probe is now showing 75 so I am making progress in the right direction. I don't want to make it too cold in there right?

Unfortunately, most of the off flavors associated with fermenting at a too high temp occur very early into fermentation so you may be a little late to the party by the time you get it to the correct temp. Once fermentation slows, the temp will begin to drop so, yes, you don't want your chamber set too cold or your yeast may drop out early and not finish their job.

What yeast are you using?

 

[marke14]

Wyeast London Ale II I think it was - it was what I had so I used it

 

[marke14]

I'm down to 73 at exactly a day after pitching ... hopefully the beer will be OK. Live and learn ...

 

[ncbrewer]

I calibrated during the specialty grain steeping, using a traditional liquid thermometer. I was surprised to see that among the 3 I was testing - a cheap analog dial 12" probe, the liquid, and the new digital one - the dial one was off by about +10 degrees F, and the liquid and digital ones were very close to one another.

You need to calibrate with an ice water bath and boiling water - correction is made by interpolation. Boiling water is easy - find the boiling point based on your elevation. Ice water bath is harder. This article tells how to do it: https://blog.thermoworks.com/thermometer/thermal-secrets-creating-properly-made-ice-bath/

 

[ncbrewer]

I personally set my temp control to 4 or 5 degrees under my target fermentation temperature to account for the additional heat put out by the yeast orgy.

There's a lot of action in the fermenter at this time, so I feel that the stick-on thermometer gives a good reading. I always control to the target temperature - never experienced any fusel alcohol problems. ymmv

 

[marke14]

There's a lot of action in the fermenter at this time, so I feel that the stick-on thermometer gives a good reading. I always control to the target temperature - never experienced any fusel alcohol problems. ymmv

So, does anyone worry about actually measuring the fermenting wort directly via a probe? Is this uncommon and people are basically controlling the chamber temperature, setting that at the 65-70 F range as per the ale yeast strains (and colder for lager strains)?

As I said I was a little shocked to see that there was a huge difference between the stick-on reading vs. the probe - like 12-15 degrees F difference.

I was surprised that my LHBS owner told me that he never bothered with a temperature probe and just controlled the fermentation chamber. It came up as I was asking him about how to modify a stopper to allow the probe's wire to pass into the carboy.

 

[Dland]

I just tape temp probe for inkbird controller on outside of fermetor, sometimes with insulation when it is very cold, otherwise, a few layers of duct tape. Seems to be pretty accurate, a lot less to worry about.

So, does anyone worry about actually measuring the fermenting wort directly via a probe?

 

[ncbrewer]

As I said I was a little shocked to see that there was a huge difference between the stick-on reading vs. the probe - like 12-15 degrees F difference.

There might not be a measurable difference in actual temperature. Check the calibration of your thermometers (see the link in post #9).

 

[Dland]

If you have a laser type mechanics or refrigeration thermometer, that is a good way to check also.

 

[marke14]

Overall, it doesn't seem that a lot of people are directly measuring the wort/beer temperature, but rather measure the temp of the outside of the fermentation vessel. Correct?

I'd imagine that on a commercial or large scale HB setup, people might go more advanced and use a probe within the liquid, as there is more at stake as the volumes get larger and larger.

 

[ncbrewer]

Overall, it doesn't seem that a lot of people are directly measuring the wort/beer temperature, but rather measure the temp of the outside of the fermentation vessel. Correct?

As far as I can tell, you're right. Some have a thermowell built in, but most seem to use a sensor on the outside. For the stick-on type, it is used as-is. For an electronic probe, most have some type of insulation over it to prevent ambient temp from affecting it too much.