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-   -   Wort Temp vs. Fermentaiton Chamber Temp (http://www.homebrewtalk.com/f163/wort-temp-vs-fermentaiton-chamber-temp-357514/)

BeezyHeezy 09-28-2012 11:43 PM

Wort Temp vs. Fermentaiton Chamber Temp
Does anyone have any experience or reasonable estimations for the expected temperature of the fermenting wort in its vessel (carboy or ale pail) compared to the temperature of the surrounding air?

I got myself a perfect little fermentation fridge (after several batches tasting exactly as ****ty solvent-like as the previous; in LA [Louisiana, not city del angels] avg. ambient temps of 75) and figured to set to something in the neighborhood of 65 to keep wort temps below 68. I don't want to immerse my temp probe (from a Johnson controller) in the wort b/c I sanitize the bare minimum and don't want to add to my workload.

I generally primary in a bucket and transfer to carboy for conditioning and clarifying and have been mostly using harvest Nottingham b/c the sweet sweet missus is eyeing the budget!


Edit: Son of a Bitch! I misspelled the damn thread title! Better pour another cold one.

jubelale 09-28-2012 11:50 PM

Temps can be anywhere from 5 to 10 degress higher depending on how vigorous the yeast are fermenting. Just tape the probe to the carboy to keep it at the set temp.

Paul07293 09-28-2012 11:50 PM

I use bubble wrap and duct tape to secure the probe to the side of the fermenter. This gets you the temp of the fermenting beer not the air in the frig.

Double-R 09-28-2012 11:56 PM

A piece of foam over the probe.. Then tape it over the bucket.
That works the best.. don't just let it hang in fridge .

BeezyHeezy 09-29-2012 12:27 AM

Sweet. I'll plan on going the foam route since I have some on hand. I might still set the controller a few degrees cooler until I have a few batches though it for comparison. Gracias.

jfr1111 10-01-2012 12:01 AM

Even if you tape the probe to the bucket, there's no guarantee the temperature won't be higher in the beer for two reasons.

First, the johnson controller (if analog) has a 2.5 degree "swing", meaning that if you set it at 60F, it'll wait until the temperature is 62.5F to kick in and then it'll keep the motor running until the temperature is 57.5F. Second, if you use a bucket, the bucket serves as insultation and the temperature might be higher inside the bucket than on the outside. Also, any controller is not necessarily calibrated.

The best way to go about is to tape the probe to the fermentor, but still have a digital thermometer that you absolutely trust to take a reading to double check, just to be sure. I used the method described above for my last beer, set the probe at 66F and woke up to a 72F beer this morning (as per my trusty thermometer)... It's better to shoot low, check with your thermometer and then go from there.

jammin 10-01-2012 12:14 AM

A thermowell is the best way to go:


Just drill a hole in the lid of your bucket. Too easy

Horseflesh 10-01-2012 04:03 AM

If you use a thermowell like that, does there need to be anything special about the temperature probe? Or can you just put in any old thing that fits?

snowbeavers 10-01-2012 07:52 AM

Funnily enough, I was thinking of the exact same thing this morning. I did a brew last night and because I live in the tropics where the ambient temperature if always over 30 degrees, we are constantly looking for ways to keep the temp down.

I bought a commercial fridge recently and turned it down to the lowest setting (+17 degrees celcius) but looked on the outside of my fermenter (coopers one that is pretty thick) and it said it was only 12 degrees (on the cheap one on the outside of the fermenter)! I panicked, took it out but it was already bubbling away. My girlfriend and I figured out that the temp inside must be much warmer because the yeast is active and because of the insulation of the fermenter.

So I put the thing back in the fridge and crossing my fingers. I think it is better to keep it cooler initially as this is when the yeast is most active.

BeezyHeezy 10-01-2012 06:32 PM

JFR, The johnson controller is digital (http://www.amazon.com/gp/product/B00368D6JA/ref=oh_details_o03_s00_i00) and the offset is programmable down to 1 degree. Good point on the calibration. I'll check it next chance I get.

Thanks for the thermowell link Jammin; I'll get some knowledge. I'm cold crashing my first brew with the setup and will keg tonight for results. If they're not as expected (delicious) I'll be doing more work to my temp control.

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