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-   -   Wort temp vs. ambient temp (http://www.homebrewtalk.com/f163/wort-temp-vs-ambient-temp-243821/)

badmajon 05-05-2011 01:34 PM

Wort temp vs. ambient temp
 
I have my chest freezer set at 65f, however, I'm not sure what the wort temp is getting to during fermentation.

Should I be doing this a different way?

o4_srt 05-05-2011 01:52 PM

Quote:

Originally Posted by badmajon
I have my chest freezer set at 65f, however, I'm not sure what the wort temp is getting to during fermentation.

Should I be doing this a different way?

Attach the temp probe for the controller to your fermenter, and cover it in insulation. This way, ambient air temps won't affect the probe, and the freezer will keep the beer at a relatively constant temperature.

badmajon 05-05-2011 01:55 PM

Quote:

Originally Posted by o4_srt (Post 2896890)
Attach the temp probe for the controller to your fermenter, and cover it in insulation. This way, ambient air temps won't affect the probe, and the freezer will keep the beer at a relatively constant temperature.

Good idea. What about with multiple fermentors in the freezer?

o4_srt 05-05-2011 02:11 PM

Quote:

Originally Posted by badmajon

Good idea. What about with multiple fermentors in the freezer?

Control the temps on the most recent batch. Beer is more susceptible to fermentation flavors during active fermentation. If you have a 2 week old batch, 1 week old batch, and a fresh brewed batch, control the fresh brewed. The other two should be mostly past the point of increased fermentation temperatures.

Or get another ferm chamber.

Krrazy 05-05-2011 02:25 PM

It will depend on the point in the fermentation cycle that they're at. If it's within maybe 3-4 days of pitching, they're usually generating more heat. The temp usually settles out once they get past that stage. From what I've read and heard, this is the point in fermentation when you're most likely to develop off flavors due to runaway temperatures. If you've brewed multiple batches at the same time, they should be somewhat aligned on that cycle and I would think the freezer temp to keep one at the right temp would be good for the others. I guess you could risk stalling a batch out if one took off and started producing a lot of heat (and that was the one with the probe attached) and another hadn't started yet. If there's a week or so between the batches, the older ones will probably be maintaining a constant temperature and you could possibly chill them down too much while your freezer is working to keep your new batch at the proper temp. That shouldn't be too much of a problem though. I use use those fermometers and if I do notice that the temp of my older batches are getting low and I don't think they're done fermenting yet I make sure I rouse the yeast a bit after they have warmed back up when the new ones go through that hot cycle.

Ideally you want to keep the fermentation temperature pretty constant but I guess that would only mean one batch at a time in the freezer and who has time for that when there are pipelines that need to be filled! ;)

Jbear 05-05-2011 08:31 PM

I just picked up a freezer yesterday to use as a fermentation chamber after my last batch had a really vigorous fermentation that spiked the temp up to 73* (sitting in a 64* ambient closet) resulting in a lot of fruity esters in my porter... My thermostat can heat or cool, so I'll also put a tiny space heater in the freezer in case it needs a boost as fermentation wraps up or to raise temps for a D-rest, etc.

I try to brew about every 2 weeks, so for multiple fermentations going my game plan is to have the freezer be dedicated to each beer for the first 7-14 days during the active/hot fermentation then I will move them to the closet I have been using to ferment. The closet maintains a steady mid-60s temp and can hold 3 vessels easily. I'm hoping that will give me the control I need without bottlenecking the pipeline. That being said though, a second chamber would be nice to have full control including being able to cold crash and whatnot. Perhaps I'll have to see just how many cheap craigslist chest freezers I can get HWMBO to approve...

What do you guys use as insulation over the temp probe on the outside of your vessel?

o4_srt 05-05-2011 08:46 PM

Quote:

Originally Posted by Jbear
I just picked up a freezer yesterday to use as a fermentation chamber after my last batch had a really vigorous fermentation that spiked the temp up to 73* (sitting in a 64* ambient closet) resulting in a lot of fruity esters in my porter... My thermostat can heat or cool, so I'll also put a tiny space heater in the freezer in case it needs a boost as fermentation wraps up or to raise temps for a D-rest, etc.

I try to brew about every 2 weeks, so for multiple fermentations going my game plan is to have the freezer be dedicated to each beer for the first 7-14 days during the active/hot fermentation then I will move them to the closet I have been using to ferment. The closet maintains a steady mid-60s temp and can hold 3 vessels easily. I'm hoping that will give me the control I need without bottlenecking the pipeline. That being said though, a second chamber would be nice to have full control including being able to cold crash and whatnot. Perhaps I'll have to see just how many cheap craigslist chest freezers I can get HWMBO to approve...

What do you guys use as insulation over the temp probe on the outside of your vessel?

If you can only heat or cool, not both, don't worry about the heater. Just run the freezer on the temp controller. I used a piece of 2" r-10 foam insulation that I cut to fit the curve of the Carboy. I notched a hole for the thermocouple so that the thermocouple rests against the side of the Carboy. I then tape the whole mass to the carboy


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