Swamp Cooler temp same as ambient?

[pdog44450]

I have only brewed ales in my homebrew career (25+ batches) all in my basement for simplicity's sake. In the summer I run an ambient temp of 66-68F*. I am currently trying a new (for me) technique of using a swamp cooler. With a wet shirt and a fan, the temp on the fermenter reads 61-62 and I can even get it down to 59 with the fan on high. My question is is my 61F* under the t shirt equivalent to a 61F* ambient temperature, or is the swamp cooler not affecting fermentation temperature as much as it seems?

Or is the answer to the question I'm asking more complicated than I think it is?

 

[GCPHomebrew]

Without a thermowell in the fermenter you can't know for sure. The rule of thumb i loosely go by is that the fermenter is 2 degrees warmer than the swamp water.

 

[Wynne-R]

I think you want the thermometer in the water. During strong fermentation the beer is well stirred by the evolving carbon dioxide. Before and after, the bottom is going to be a couple of degrees cooler than the top.

I ferment with a carboy in a water bath, and the temperatures reliably track within a degree. That’s with the water up to the beer-line.

Try moving the probe to different spots. I think you’ll find that the temperature on the fan side is lower than the back side. This is measurement error from evaporation cooling the thermometer.

 

[kh54s10]

I think you are mixing things up. Ambient is the air temperature of the room. With a cloth around the fermenter in water and a fan blowing on it you get some evaporation cooling. The important temperature is the temperature of the wort itself. If you have a stick on fermometer it will be pretty close to the wort temperature if the cloth/water is not cooling it.

Control the temperature of the wort. You don't really care about the temperature of anything else!

When I used a swamp cooler I used about 8 inches of water and rotated ice bottles as needed to control the temperature. No t-shirt, no fan.

 

[pdog44450]

I think you are mixing things up. Ambient is the air temperature of the room. With a cloth around the fermenter in water and a fan blowing on it you get some evaporation cooling. The important temperature is the temperature of the wort itself. If you have a stick on fermometer it will be pretty close to the wort temperature if the cloth/water is not cooling it.

Control the temperature of the wort. You don't really care about the temperature of anything else!

When I used a swamp cooler I used about 8 inches of water and rotated ice bottles as needed to control the temperature. No t-shirt, no fan.

I'm not mixing it up I am aware that ambient is air temp. My ultimate question is if my stick on thermometer is reading 61 with a wet t-shirt on it, is it equivalent to, if I didn't have the t-shirt, the fermenter being in a 61 degree ambient room. Just so I can estimate the wort temperature more closely

 

[pdog44450]

Without a thermowell in the fermenter you can't know for sure. The rule of thumb i loosely go by is that the fermenter is 2 degrees warmer than the swamp water.

Simple enough, thanks

 

[pdog44450]

I think you want the thermometer in the water. During strong fermentation the beer is well stirred by the evolving carbon dioxide. Before and after, the bottom is going to be a couple of degrees cooler than the top.

I ferment with a carboy in a water bath, and the temperatures reliably track within a degree. That’s with the water up to the beer-line.

Try moving the probe to different spots. I think you’ll find that the temperature on the fan side is lower than the back side. This is measurement error from evaporation cooling the thermometer.

My thermometer is a stick on that's on the side of the fermentor. I don't want to take the airlock off and check the temperature of the wort just to avoid any contamination or oxygenation issue so at this point I am just trying to make an estimate of the wort temp.

 

[Yooper]

My thermometer is a stick on that's on the side of the fermentor. I don't want to take the airlock off and check the temperature of the wort just to avoid any contamination or oxygenation issue so at this point I am just trying to make an estimate of the wort temp.

Without checking inside, you can safely assume the beer inside the fermenter is within a degree or two of the reading on the stick-on thermometer.

 

[kh54s10]

If you have a stick on fermometer it will be pretty close to the wort temperature if the cloth/water is not cooling it.

When I used a swamp cooler I used about 8 inches of water and rotated ice bottles as needed to control the temperature. No t-shirt, no fan.

Without checking inside, you can safely assume the beer inside the fermenter is within a degree or two of the reading on the stick-on thermometer.

The stick on thermometer is pretty close. If you are to err - err on the cold side.