Swamp Cooler: How cold is too cold?

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simps984

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Hey all, so I've rigged up a swamp cooler for the first time to ferment out a roggenbier. My recipe calls for a 62 degrees fermentation temp. My basement right now holds pretty steady at 72.

For the setup I've got a bucket filled with water that reaches up around halfway up my 6 gallon carboy. I have two towels draped over the carboy and pour water on these every few hours. I also have a pretty good sized fan blowing on these towels, set to "high" and this generates a great deal of wind. Finally, I swap 3-4 small 6oz frozen water bottles every 8 hours or so.

My question: Is this making things too cold? Cold enough to halt/severely slow down fermentation? What component of the swamp cooler should I undo, if any?

Cheers!
 
each type of yeast has a Temp Range. For ales anything below 50 degrees would make the yeast go dormant and flocculate out....but hig 50's low 60's is great for the majority of ale yeasts. For Belgians you actually want to have it hotter to produce the typical belgian funkiness....
 
each type of yeast has a Temp Range. For ales anything below 50 degrees would make the yeast go dormant and flocculate out....but hig 50's low 60's is great for the majority of ale yeasts. For Belgians you actually want to have it hotter to produce the typical belgian funkiness....

Righto, so I guess I'm wondering if all my swamp cooler measures are dropping the temps down to that 50 degrees level. I should also add that I'm using a recipe from Jamil's book Brewing Classic Styles, and he recommended using Wyeast's Weihenstephan yeast, but fermenting it below its range, @ 62F.
 
I doubt you are getting yours to 50 degrees, without using a lot of ice and rock salt....I have only EVER gotten my swamp cooler down to 57 degrees. And that was with a ton of frozen waterbottles.

fermenting.jpg


The water bath was 57 degrees, but the temp strip on the big fermenter was a few degrees higher...So I really don't think you need to worry about your yeast going dormant, so just relax....
 
Quick question: Do you have a stick-on thermometer on your fermenter?

Nope, I have a regular thermometer in the room that I know is accurate and it consistently reads 72F, I take the temperature of the swamp cooler water with a probe thermometer, which shows 62-66, depending upon how many frozen bottles of water I have in there. Anybody have an estimate as to how much more cooling power the soaked towels with a large fan constantly blowing on high has? In other swamp cooler threads, some have commented on this technique, saying it "super charges" your swamp cooler. I guess I'm just trying to refine the method a bit.
 
I would suggest spending 3 bucks and getting the stick-on thermometer for your fermenter. This way you will know what the actual temp is and you won't have hypothesize.

Start with just the water basin and a wet towel. If that's not cool enough add the fan, then the ice.

Where are you located? Depending on your ambient conditions, specifically the wet bulb temp, the wet towel may be all you need.
 
I would guess that the temp of your fermenting wort is pretty close to the temp. of the bath it is sitting in. While the fan and t-shirts probably help, hard to believe the wort could be much, if at all, cooler than the bath they are sitting in??
 
I would guess that the temp of your fermenting wort is pretty close to the temp. of the bath it is sitting in. While the fan and t-shirts probably help, hard to believe the wort could be much, if at all, cooler than the bath they are sitting in??
I agree. As long as it's in a water bath or similar where there is direct contact between cooling liquid and the carboy then the beer inside should be close to bath temp. The beer will be a little warmer because of the heat generated by fermentation. If it were sitting in a room with just air surrounding the carboy then it could be noticably warmer inside the carboy because the heat transfer via air is way less efficient than the heat transfer via water. The fan and towels/t-shirts do help but don't lower the temp of the carboy contents below that of the bath. IME, for that to happen the room air would have to be quite cool and very dry (in which case you prob wouldn't need the bath to begin with).
 
I would guess that the temp of your fermenting wort is pretty close to the temp. of the bath it is sitting in. While the fan and t-shirts probably help, hard to believe the wort could be much, if at all, cooler than the bath they are sitting in??

I've read that the wet towels + fan have an evaporative effect that really cools things down. Imagine if you're in a rainstorm and your clothes get soaked, and then the wind picks up, making you very cold. Same thing.
 
Yes simps, while I agree, the fact remains that half of the carboy is submerged in the cooling bath and the two will tend to equalize. Perhaps the evaporative cooling is lowering the temp of the brew, which is lowering the temp of the bath the beer is in.
 
Wouldn't you get more life and lower temps by doing this in a cooler, with a lid that can be closed (except for the airlock poking up)?

I'm going to have to do this pretty soon and have been contemplating the exact process. My plan is to use frozen 2L bottles and rotate with fresh out of the freezer when they thaw. Isn't it hard to keep a constant temp?
 
Wouldn't you get more life and lower temps by doing this in a cooler, with a lid that can be closed (except for the airlock poking up)?

I'm going to have to do this pretty soon and have been contemplating the exact process. My plan is to use frozen 2L bottles and rotate with fresh out of the freezer when they thaw. Isn't it hard to keep a constant temp?

Actually once I get the water in the swamp cooler to say 65-68° it does not move all that much even in warm ambient air temps. Takes a lot to move 8-10 gallons of water up or down with just air temp.
 
I've read that the wet towels + fan have an evaporative effect that really cools things down. Imagine if you're in a rainstorm and your clothes get soaked, and then the wind picks up, making you very cold. Same thing.
Yes simps, it does have some effect. I forgot how much humidity can affect it and I live in a very humid climate so it's least effective here. I have always had to use some sort of swamp method or something to keep fermenters cool. Sitting in a water bath, wet towels, a fan blowing right on it...I've done it for years and measured the resultant temps. You get a few degrees (depending on the air temp and humidity) but that's about it IME. The 'cooling' happens due to the water evaporating and way less water evaporates when it's humid vs. dry (that's why you sweat more when it's humid...evaporative cooling is so much less efficient when it's humid). If you have a drier climate it prob works noticably better than it does for me.
 
Yes simps, it does have some effect. I forgot how much humidity can affect it and I live in a very humid climate so it's least effective here. I have always had to use some sort of swamp method or something to keep fermenters cool. Sitting in a water bath, wet towels, a fan blowing right on it...I've done it for years and measured the resultant temps. You get a few degrees (depending on the air temp and humidity) but that's about it IME. The 'cooling' happens due to the water evaporating and way less water evaporates when it's humid vs. dry (that's why you sweat more when it's humid...evaporative cooling is so much less efficient when it's humid). If you have a drier climate it prob works noticably better than it does for me.

+1

Evaporative cooling will produce a temperature of 2-3 deg over wet bulb. Wet bulb temperature is the temperature of the water suspended in the air. This temperature varies from place to place and from month to month. With a little creative searching, you can find a wet bulb chart for your region online.
 
Do you guys submerge the temp strip in the swamp bath or do you keep it dry?

I guess my question is where on the fermenter do you place the strip?
 
Do you guys submerge the temp strip in the swamp bath or do you keep it dry?

I guess my question is where on the fermenter do you place the strip?

Keep it dry. I have mine placed higher than the water level in my swamp cooler. I have read they don't read accurately when they are wet.
 
To the original post: I don't think you'll get much more than a 10 degree pulldown with that setup, so you won't overchill the brew. I used to do the bucket with frozen bottle method, but it was always a PITA and never worked because we used to leave the temps at 78 24/7. This year in a different apartment I'm using the same bucket with a towel wrapped around a 6.5g carboy, with about 6" of water in the bottom of the bucket, and a fan blowing on the towel. I add water and soak the towels every 12 hours or so. It has been going from room temp of 74 to 65, with some parts reaching 59 directly under the fan. These readings are off the sides of the towel though with an infrared thermometer. The beer itself all wrapped up hasn't hit under 64, so I don't think you have to worry about cooling too much.

Previous to this great working swamp cooler, I was afraid of brewing anything that needed to be fermented under 72 degrees, but now I'm confident that I can brew down to 65 :D Opens up a whole new world of experience. Now I just need to get a rolling boil going on my small apartment burner (I've seen the threads, and will be trying the insulation soon ;) )
 
I doubt you are getting yours to 50 degrees, without using a lot of ice and rock salt....I have only EVER gotten my swamp cooler down to 57 degrees. And that was with a ton of frozen waterbottles.

fermenting.jpg


The water bath was 57 degrees, but the temp strip on the big fermenter was a few degrees higher...So I really don't think you need to worry about your yeast going dormant, so just relax....

Thread dig.

For a swamp cooler, does the water level need to be at the same level as the brew (5 gallons or so)? Can it be at the same level? Is there a benefit from water level being the same as the brew level?



Here is a pic of mine:

P5040774.jpg


I have a stick on thermometer on my fermenter, but the water level is too high to read it so I have a floating thermometer I leave in there. Which leads me to my next question.

Even after initial fermentation is complete (its been just over 2 weeks), is the brew going to remain 5°F warmer than the water temp? Or is that just during initial fermentation?

Also, I have been keeping the water temp at 60-65F, is that fine?

Note: I took the water bottles out because it got pretty cold last night and the water temp got into the low 50's, so I am letting the water warm back up.
 
Trevor,

I'd be careful about leaving the adhesive thermometer submerged. The website for those things say they are water resistant, but not water *proof*. They say after a long period in water the water can leach under the strip and kill it. Sure, only 3 bucks, but I thought I'd give you the heads up.

As for your question, I'm sorry I don't know the answer. I have yet to actually use this set up.
 
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