Need to get something to lower temp during fermentation

General Homebrew Discussion
1

Hey All,

I have done two brews that were fairly successful but maybe a bit under on what ABV should have been. Doing research, I think part of problem is temp where 2-4 week fermentation goes on is only about 73-74. Is there anything out there turn key or close to turn key where I can set 5 gal carboy in and dial in whatever temp I want (for last two they suggested 68).?

thx

2

An old fridge from Craigslist and a temperature controller is the easiest way

3

A chest freezer hooked up to an external temp controller is a common way to control fermentation temps. What makes you think your ending up with low abv? Are you using a hydrometer to take original and final gravity readings? The reason for fermenting at 68 is flavor, the warmer fermented beer will finish at the same gravity

This is an example of a temp controller
https://www.amazon.com/gp/aw/d/B015E2UFGM/ref=mp_s_a_1_1?ie=UTF8&qid=1497531690&sr=8-1&pi=AC_SX236_SY340_QL65&keywords=temp+controller+for+brewing&dpPl=1&dpID=41dREFV9XIL&ref=plSrch

You set your fermentation temp and the unit turns the freezer/heater on and off to maintain whatever temp you set

4

Yes, using OG and FG with hydrometer. Now I am confused, guy at homebrew store mentioned my storing temp would affect ABV.

5

The fermentation temp, except for extremes, which is not the case here, won’t effect FG. That being said controlling fermentation temp is very important and should be pursued.
If you want help trouble shooting the abv/fg issue you could post your recipe and procedure.
here are a few things to consider:

  1. The final gravity in a recipe or brewing software is always an estimate. If you are fairly close and the beer doesn’t taste overly sweet your good. Ex: 1.012 estimated fg; 1.015 actual FG and beer tastes OK, no problem. 1.012 est FG and 1.020 actual fg and beer tastes sweet= problem.
  2. Too much specialty grains (crystal, carmel, etc) can result in a higher fg
  3. Extract doesn’t attenuate as well as properly mashed all grain wort.
    4.If you are doing all grain mash temp effects attenuation
6

First off, those temps are very much on the high side unless you are fermenting belgian stuff.  Ideally, you want low to mid 60’s for ales.  Google swamp cooler if a fridge and t-stat is too much for you now.  Lastly, I agree with pete, temps do not really affect FG and it likely due to extract and/or specialty grains.

7

So glad I have found this forum, you guys have helped a bunch. I think I found a chest freezer for $150 that will hold two carboys. I will get the temp controller and should be in business :)…Brewing Saturday so perfect timing.

Thx again

8

All of this.  As a cheap workaround (if$ is an issue) use a plastic tub of water, add the fermenter to it and add frozen water bottles as needed to hold the water temp to your target fermentation temp. I did it for a while and it works.

9

If you’re only a few degrees over you may not even need ice; just setting the fermenter in a large bin of water will keep it a little below ambient temperature.

10

Yes.  This is true.  On the flip side, if you’re doing Belgians you can also add an aquarium heater to the water bath and jack up the temperature.  OF course, this works better with an external temp controller like the one linked above.

FWIW, the set it and forget it nature of controlling temp in a fridge/freezer (you can also add heating elements here if you want to) is awesome.  Making lagers was never so easy.

11

OK. I officially have the chest freezer and temp control will be here tomorrow. Should I tape probe to carboy or just inside the freezer will work too?

thx

12

I have a piece of reflectix insulation taped to the carboy that holds the probe against it.

13

Both work but taped is better.  I have the old school Johnson t-stat with aluminum line and don’t want to risk kinking the line it so it stays in one place in fridge.  Many thanks to Andor for the link!  The dual cold/heat t-stats have sure come down.  Might be time for an upgrade…

14

Pretty much how I use my thermostat. I tape a probe for a indoor/outdoor thermometer to the fermenter so I can monitor beer temp vs ambient freezer temp vs room temp. I usually need to keep the freezer temp below what I want to ferment at so it needs a bit of monitoring.

15

Tape is good. I try to put something like a small piece of bubble wrap between the tape and probe to insulate it for a more accurate reading… you can also get a thermowell that way your temp is coming from within the carboy and not the wall of it.

16

something like this work?

17

Themowells are cool, but in my experience there is too much lag with a standard thermostat. By the time the probe is at target, the chamber and outside of the vessel is well below. This results in large negative temp swings.

Fancier controllers are able to compensate for this overshoot, but are more expensive or may require multiple components and wiring.

18

Well, the reverse is true with the probe on the side. The center of the fermenter is at a higher temperature during fermentation.  So you either get an unknown higher temp or an unknown lower temp where your probe isn’t.

19

My goal is for a stable temp, as much as possible.  That temp is likely to be within a band of several degrees, but that’s OK.  The actual temp to me (assuming it is within range of where it should be) is not as important as a stable and consistent temp.

20

Personally, I’ve never seen a measurable difference.