Ferment/ambient temp changes - how long to change?

[barleyfreak]

Does anyone know how to calculate how long it takes 5 gallons to adjust to changes in ambient temperature? It is cold in the winter here and my sole source of heat is a woodstove. My last ale ferment had temp swings of 74 at one end and 62 the other. Assuming that the ambient temp was equally divided in both climbing and falling between those two temps, then doesn't it make sense that the beer's temperature would always be playing catch up to those temps and really have a range closer to something like 66 to 70?

In other words if the ambient temp low and high do not stay there for long, then the beer will never actually reach that temp extreme. If anyone knows an online calculator or formula for calculating the change in temp of a liquid in ambient temp changes that would be helpful. I wasn't able to find one.

**Disclaimer** I do understand that ambient and ferment temps are different -- I make adjustments for that.

 

[NordeastBrewer77]

read these fermentation temps and controlling temps
personally, i chill my wort to fermentation temperature, pitch, and hold temps. those links will give you some ideas on how to best control fermentation temps.

 

[barleyfreak]

Thanks for the links, but they don't answer my question. I'll rephrase it. I'm trying to find a formula for the temperature change of beer equalizing to ambient temp. Take 5 gallons of fermented beer at 60 degrees and put it in a room at 75. How long does it take for the beer to stabilize at that temp? I tried googling it with water but couldn't find anything. There's gotta be a calc somewhere. An 8 oz glass of water would rise to 75 in xx minutes, but 5 gallons would obviously take longer due to larger thermal mass.

I don't have room for a swamp cooler (no basement, no room in house or garage) and I have done water baths before, but if I can maintain a reasonable temp in the house, it is far easier. That is why I'd like to know the answer to this.

 

[NordeastBrewer77]

i understand your question. but if you cool to fermentation temps, pitch, and hold temps there's no need to sweat the equation.\
as far as room, as you can see in the pics, the 'swamp cooler' we're talking about here isn't the kinda that cools a garage, it's a water bath and takes no more room than your fermenters.
i was simply trying to give you a few suggestions on how to maintain temps, which i feel is far better than pitching at 60, placing into a 75 degree ambient room, and hoping the temps don't rise too fast. which they will, fermentation is exothermic and 60 degree wort in a 75 degree environment will quickly raise to 80 degrees or above, way too warm for almost any ale strain.

 

[Phunhog]

I don't think there is an easy answer to your question. It would depend on how much heat your fermenting beer is producing. Obviously that is going to change based on where it is in its' fermentation cycle. Another factor is the shape and material (glass, plastic, stainless) of your fermenter.

 

[Frodo]

Does anyone know how to calculate how long it takes 5 gallons to adjust to changes in ambient temperature? It is cold in the winter here and my sole source of heat is a woodstove. My last ale ferment had temp swings of 74 at one end and 62 the other. Assuming that the ambient temp was equally divided in both climbing and falling between those two temps, then doesn't it make sense that the beer's temperature would always be playing catch up to those temps and really have a range closer to something like 66 to 70?

I've never seen a calculator. But in my experience of watching temps closely on my fermenters (6.5 gal glass), yes the temp of the beer is always behind diurnal ambient temp swings and usually resides somewhere in between the min and max temp swings except for when fermentation is really going strong - then all bets are off, depending on timing you could end up with your fermenter reaching a much higher temp than the max ambient temp.

edit: example: lately my ambient temp has been swinging between about 54 and 62 degrees, but my "aging" fermenters have only been cycling up/down 1 degree or so, from around 58 to 59 degrees according to the stick-on Fermometers.