Wort Heater? (for a dry finish)

Howdy all.

Some of the recipes I see, specifically for the Westvleteren 12 clone, show a fermentation at a higher temperature such as 80F. I though the yeast produce a ton of energy and got it up here, but I see folks talking about keeping the temp there rather than letting it occur naturally, or raising the temp if the FG is ending up too high.

What is used to heat the wort, if this is a common practice to finish the beer where you want it? Also, if it is not part of a standard fermentation schedule (ex: my beer is just too high a gravity), when should I be heating the wort? I just want to be certain this won't have adverse effects to my beer.

I was going to make a wort chiller sometime soon, but as I am fermenting a strong Belgian ale right now, I may need a wort heater first!

Typically, we simply put a heavy shirt/jacket/coat on the fermentor, depending on what temps you are at and where you want to be, this takes a little monitoring. You could probably use an old water bed heater, or a heating pad? I don't know if they will be low enough though. Vendors sell fermentation heaters as well I believe.

we have a fermentation heat belt that just straps around the bucket. Works very well and adds about 5 degrees to the fermentor.

yeast produce a bit of heat energy, but not really 'a ton,' (they consume <10% of the caloric value of the sugar in the wort). It may be difficult to maintain 80+ degree temperatures, especially as fermentation slows (when it's the most critical to keep the temps up).

I normally place my carboy into a bucket, and fill the surrounding space with water. An aquarium heater in the water is an effective means of boosting fermentation temps. My normal process (with any beer) is to boost temps by about 5 degrees as the krausen starts to fall - and keep it there for 5 to 10 days to finish out and clean up any diacetyl, acetaldehyde, etc.

prosper said:

.... My normal process (with any beer) is to boost temps by about 5 degrees as the krausen starts to fall - and keep it there for 5 to 10 days to finish out and clean up any diacetyl, acetaldehyde, etc.

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Seems there is a downside to me using my plastic bucket, as I can not monitor that as readily, if at all. I will work on the aquarium heater though, setting that up this upcoming weekend.


Check this reasoning, see if it works out: 1 week at room temperature (high 60's), then 1 week at a higher temp (mid to high 70's), and then check to see where the gravity is. If still too high, keep the hot water on it, otherwise let it coast at room temp.

Do I need to have these higher temps to get it to finish, or can I substitute heat with patience?

buy a $5 floating thermometer and drop it in the water. Presto - easy to monitor fermentation temperature. Water conducts heat much much faster than air and I've found that, with this setup, the water temperature == the beer temperature (unlike an air-cooled fermentation, where the temperature of the wort could be several degrees warmer than ambient).

Your logic otherwise sounds good. However, heat works better than patience - moreso with certain yeast strains than others. Wyeast 3724 (dupont saison), for example - it will often stabilize ~1.030 forever, unless boosted into the mid to high 80's to finish out. I have noticed that with some of my beers that I bottles over the winter experience a considerable boost in carbonation if they make it to the hot summer days. And I rarely ever bottle beer before it's been sitting for at least 4 weeks in the fermenter. This problem went away after I started boosting the finishing temperature.

One other thing to consider - temperature swings will affect the yeast more than the average temperature. Going from 65F to 80F night-to-day will often cause your yeast to floc out early, and not attenuate fully no matter how much time you give it. Maintaining a very steady 70F would be much more preferable. I like the carboy-in-a-bucket technique because the mass of coolant water adds a large thermal buffer to help even out day to day temperature swings

If you don't want to have to babysit your wort, you really need to get one of these with this and this.

Then I just wrap a blanket around the carboy or bucket to hold the heat in.

prosper said:

. . . .I normally place my carboy into a bucket, and fill the surrounding space with water. An aquarium heater in the water is an effective means of boosting fermentation temps. My normal process (with any beer) is to boost temps by about 5 degrees as the krausen starts to fall - and keep it there for 5 to 10 days to finish out and clean up any diacetyl, acetaldehyde, etc.

Click to expand...

How high of temp can this process maintain? I'll be doing a couple of saisons soon and would like to ferment high at about 90F.

JJL said:

If you don't want to have to babysit your wort, you really need to get one of these with this and this.

Then I just wrap a blanket around the carboy or bucket to hold the heat in.

Click to expand...

That's the expensive way. A bucket plus an aquarium heater (which includes a thermostat) costs < $30 and works just as well (even when unattended).

COLObrewer said:

How high of temp can this process maintain? I'll be doing a couple of saisons soon and would like to ferment high at about 90F.

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depends on how big an aquarium heater you buy, and whether or not you insulate the bucket. I've found that 40W heater in an insulated bucket can maintain an temperature delta of 20*C, but a 400W heater in an un-insulated bucket will struggle at that delta.

In the dead of winter here, I've lagered beer in my (un-heated) garage with this technique (though you'll need an external temperature controller because most built-in aquarium heater thermostats don't go down to the 35*F range )