Swamp cooling - noticeable difference?

I grabbed a $4.57 storage tote for my latest batch (double IPA) and filled it half-full of water, then put the fermenting bucket in that and I have a couple of liter bottles of water freezing to drop in there.

I am wondering, though, for anyone who has taken steps like these to keep fermenting temps down--was it a noticeable difference in your beer flavor? I've read that keeping fermentation temps down and pitching enough yeast are two things that can have a big impact on beer flavor, but is it worth the marginal effort?

I'm just trying to get my processes down on the fermentation right now, still extract brewing but thinking about jumping to all-grain. But I figure, take one thing at a time.

Controlling fermentation temps so you can ferment on the lower end of the temperature range does have a positive impact, less chance of off flavors that higher temps cause.

Also allows you to be able to use different yeasts that you couldn't use before.

If you can keep ambient temps reasonable you may be able to pull of a nice beer without one. For a big beer it's even more important. They will get noticeably hotter from fermentation.

I've brewed beer without, with and in my chest freezer. There is no going back after the chest freezer. Temp is one of the few controls we have over yeast. Only yeast can make beer.

This one is a double IPA so it's a little bit up there on the OG but nothing past 70 or so.

I'll post up in a month or so when it's kegged if there's anything noticeably different.

Don't forget to put a t-shirt on the carboy or bucket and to blow a fan on it. Even without ice, that is usually enough to drop the temp of the fermenter to 8-10 degrees below ambient.

I'm going to respectfully disagree with a previous post --

As a matter of thermodynamics, you're never going to cool your wort below room temperature with a swamp cooler, sans ice or some other cooling solution.

Putting the fermentation vessel in water aids thermal transfer, i.e., it helps your fermenter transfer internal temperature to the external environment (because water is a better conductor of heat than air). Blowing air on your fermentation vessel also aids thermal transfer. If your fermentation is vigorous and it's heating up the wort, these steps will help you keep it down to room temp.

But you will never, ever get your fermenting wort below room temperature without ice or some cooling solution. Water bath or increased airflow just increases the rate at which your wort reaches equilibrium with the environment. To cool below room temp you need to "sink" some of that heat off.

Thank you for replying though! I am glad for helpful comments.

jkreuze said:

As a matter of thermodynamics, you're never going to cool your wort below room temperature with a swamp cooler, sans ice or some other cooling solution.

Putting the fermentation vessel in water aids thermal transfer, i.e., it helps your fermenter transfer internal temperature to the external environment (because water is a better conductor of heat than air). Blowing air on your fermentation vessel also aids thermal transfer. If your fermentation is vigorous and it's heating up the wort, these steps will help you keep it down to room temp.

But you will never, ever get your fermenting wort below room temperature without ice or some cooling solution. Water bath or increased airflow just increases the rate at which your wort reaches equilibrium with the environment. To cool below room temp you need to "sink" some of that heat off.

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Interesting............because laws of thermal transfer aside, it does work.

The idea is "evaporative cooling". Of course, it works much better in a desert than in Florida's humid environment. But it DOES work.

Never ever say "never ever", my friend.

Swamp coolers work because of the evaporation of the water in the t-shirt clinging to the carboy. Put a fan on it to speed up the cooling and you absolutely will drop below ambient air temps. How much varies on things like humidity, fermentation generating heat, etc.

People have been using swamp cooler "air conditioners" for many many years without ice.

The misconception is people thinking they have a samp cooler just by putting their fermenter in a bucket of water. The t-shirt is critical as it introduces the evaporation.

Living in a desert i can tell you swamp coolers work like a charm or there wouldnt be one of these on top of every house in the neighborhood.

JetSmooth said:

The t-shirt is critical as it introduces the evaporation.

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So is the fan. It's the air movement that increases the evaporation, which increases the cooling.

The t-shirt wicks up the water, and the fan blows across it causing evaporation. Then, the t-shirt continues to wick up water, etc.

In humid climates, it doesn't work nearly as well because of the lower evaporation rate. But it works brilliantly in drier climates.

YooperBrew said:

So is the fan.

*snip*

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Yup. Also totally important. But some people skip the T-shirt and just point a fan at the fermenter sitting in the tub of water. Not going to be very effective that way.

jkreuze said:

I'm going to respectfully disagree with a previous post --

As a matter of thermodynamics, you're never going to cool your wort below room temperature with a swamp cooler, sans ice or some other cooling solution.

Putting the fermentation vessel in water aids thermal transfer, i.e., it helps your fermenter transfer internal temperature to the external environment (because water is a better conductor of heat than air). Blowing air on your fermentation vessel also aids thermal transfer. If your fermentation is vigorous and it's heating up the wort, these steps will help you keep it down to room temp.

But you will never, ever get your fermenting wort below room temperature without ice or some cooling solution. Water bath or increased airflow just increases the rate at which your wort reaches equilibrium with the environment. To cool below room temp you need to "sink" some of that heat off.

Thank you for replying though! I am glad for helpful comments.

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Check out latent heat.
This is a very important part of thermodynamics that deals with substances changing state from solid to liquid to to vapor, or vice versa.
How do you think a fridge, freezer, or air conditioner works. You're probably aware that all three have compressors (which convert gas into liquid) generating heat, but it is the subsequent evaporation of that liquid that generates the cooling.

-a.

Thanks for the correction, I read up on evaporative cooling, and I was wrong. But I learned about something new, which is good!

Anyone have hard data on wort temp changes due to evaporative cooling? I am just wondering about efficacy. I guess I can just temp out a batch myself this week.

jkreuze said:

Thanks for the correction, I read up on evaporative cooling, and I was wrong. But I learned about something new, which is good!

Anyone have hard data on wort temp changes due to evaporative cooling? I am just wondering about efficacy. I guess I can just temp out a batch myself this week.

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Do you remember on the first page where you erroneously told me I was wrong? Back there I mentioned that I get an 8-10 degree drop from ambient. But as others stated, it depends on relative humidity, temperature, surface area, wind speed, etc.

Cheers!

Humidity is a "huge" factor for swamp cooling. I get hardly any cooling out of it because I live right on the everglades and would rather just deal with changing out ice 2-3x a day.

Jdecarol said:

Humidity is a "huge" factor for swamp cooling. I get hardly any cooling out of it because I live right on the everglades and would rather just deal with changing out ice 2-3x a day.

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Yeah- that's why it's really impossible to say in your case how much of a cooling effect you'd get. In the Everglades, it'd be negligible since they're already at like 99% humidity. Same with Louisiana. But in Phoenix, you'd probably drop 8-10 degrees, like KingBrian, or even more. It depends so much on the humidity already in the air.

You could try it and see. I bet it would change during weather changes, too, so you may not always have the same results. However, if your climate is reasonably not humid, it should work. I live in a cool climate, and I find that just a water bath in my Yooper Lagerator with a frozen water bottle added to the water will keep my temps in the low 60s. (My Yooper Lagerator is an Igloo cooler with wheels that I made a special lid for so that the airlock pokes out- it holds temps perfectly for me).

I think the best part is not "swamp" or "evaporative'" it simply is thermal mass. It will ballast the temps to keep them consistent.

If I have days starting of a low of 50 and a high of 70 all I need is a good sized tub of watter to keep my fermenter in the low 60s. I never used the shirt and I live in a desert.

The temperature that can be attained by evaporative cooling is dependent upon the wet bulb temperature of the location. The wet bulb temperature is the temperature of the water vapor in the air. It varies from place to place, day to day and season to season.

Here is what I have learned from my experiments. I have played with this quite a bit. There are a lot of variables at work here. I ferment in my basement in my fall out shelter. (If we get nuked I'm gonna have a great time before I go!!!) The ambient temperature at this time of year in this room is about 65 F. I also have a pretty decent dehumidifier, which I have set to hold a constant humidity of 65%. (It also gets rid of the funky armpit smell!) Also worth mentioning I am about 630 feet above sea level. My control beer is 1.070 OG 5.25 gallon batch using WLP001.

I use the wet t-shirt method with a medium sized box fan positioned approx. 1 foot away from the carboy. The carboy (6.5 Gallon glass) is sitting on the concrete floor which is about 60 F.

Without the wet t-shirt during active fermentation = 75 F
With wet t-shirt only (fan off) during active fermentation = 68 F
With wet t-shirt and fan on low during active fermentation = 64 F
With wet t-shirt and fan on medium during active fermentation = 60 F
With wet t-shirt and fan on high during active fermentation = 57-58 F

I think the key in my case is the dehumidifier. I am able to hold quite steady temperatures and take a fair stab at how things will work out. It does vary a bit so I usually just take a pretty good guess and check it when active fermentation gets rolling and tweak as necessary. Hopefully you can find this useful.

Also wouldn't the law of conservation of energy be the main mechanism behind evaporative cooling? The act of water changing states from liquid to gas would require energy (in the form of heat). Probably throw a little bit of the law of conservation of mass in there as well. I'm not sure, I should probably google it.

livErD69 said:

I think the key in my case is the dehumidifier.

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One way to know for sure. Run the tests with and without the dehumidifier running.

livErD69 said:

Here is what I have learned from my experiments. I have played with this quite a bit. There are a lot of variables at work here. I ferment in my basement in my fall out shelter. (If we get nuked I'm gonna have a great time before I go!!!) The ambient temperature at this time of year in this room is about 65 F. I also have a pretty decent dehumidifier, which I have set to hold a constant humidity of 65%. (It also gets rid of the funky armpit smell!) Also worth mentioning I am about 630 feet above sea level. My control beer is 1.070 OG 5.25 gallon batch using WLP001.

I use the wet t-shirt method with a medium sized box fan positioned approx. 1 foot away from the carboy. The carboy (6.5 Gallon glass) is sitting on the concrete floor which is about 60 F.

Without the wet t-shirt during active fermentation = 75 F
With wet t-shirt only (fan off) during active fermentation = 68 F
With wet t-shirt and fan on low during active fermentation = 64 F
With wet t-shirt and fan on medium during active fermentation = 60 F
With wet t-shirt and fan on high during active fermentation = 57-58 F

I think the key in my case is the dehumidifier. I am able to hold quite steady temperatures and take a fair stab at how things will work out. It does vary a bit so I usually just take a pretty good guess and check it when active fermentation gets rolling and tweak as necessary. Hopefully you can find this useful.

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This is great information to know. Thanks for sharing the results with us.

np

Nice! I'm going to try this on my next batch.
Just another reason wet t-shirts are sexy...

I've been experimenting with improving the swamp cooling method and found that using a wicking type runners shirt (like CoolMax) instead of a cotton t-shirt really increases the evaporation efficiency.

See similar thread HERE.

I am using an actual swamp cooler set up for the first time. I have 2 primaries in a large cooler with the t-shirts and fan and I am swapping out a frozen 1 liter water bottle. It was 90* yesterday, and had 2 active fermentations down at 64*. Works great!