Brew Tips #14b: Temperature Control part 2
YARRRR! I don't usually do a two parter here. But, this is one I felt needed a bit more information and a follow up of sorts. It is supposed to be one of the most important things after all. I may even do a third part once some of these beers finish.
As mentioned, I bought a wine cooler with a supposedly near high enough max temperature (14C) for ale yeast. As many will point out, fermentation is exothermic and actual fermentation temperatures can push that temperature up even further inside of the fermenter. So I was hopeful that this 14C would effectively be closer to 16-18C inside of the fermenter. 18 would be ideal, but most people had good results with 16C for many yeast strains.
I don't have a temperature control module yet. Though I will probably get one at some point. For now, I just have an analog meat thermometer in there. Just sitting on top of my fermentation pail.
The first batch I put in, I think probably had a stalled fermentation. I panicked a bit, when after 24 hours, there was absolutely no activity. So I went and pitched another packet of yeast. It got started after another 12 hours, but seemed sluggish and only went on at a slow pace for a few days. Now, because I added the second pack, another option is that it took off like a rocket while I wasn't looking. It wasn't a high gravity beer. So seems possible. Anyway, temps at the top of the fridge reported a chilly 10-12C, which means that down near the bottom was probably even colder. This is why I'm thinking it possible that the yeast just fell out of suspension and I'll have a disgustingly sweet beer to deal with. Anyway, I bottle on Saturday, will have a better idea then.
To try and figure out what was going on a bit more, I picked up some fermometers. Those peel and stick thermometers for the fermentation pail. The second batch I did things a little differently and paid a lot more attention.
Keep in mind, if that first batch is ruined, it is because I let I things get WAY out of the acceptable range and fermentation never had a chance to get fully started. Also keep in mind, I'm not even sure if I screwed up that batch yet. Beer making IS pretty darn forgiving. But fermenting in a fridge that is actually pushing fridge like temperatures (with an ale yeast) is quite a big no-no. :)
Second time around I properly aerated the wort. I usually do. The first wine cooler batch I didn't for some reason. The next thing I did was watched the fermometer at regular intervals to get an idea how quickly or slowly the temperature was changing and roughly where it was at.
Given the paranoid ramblings of virtually everyone on the forums I was a little concerned with what I did next. But I noticed after 24 hours that the fermometer was dropping to levels I wasn't happy with... so I shut the fridge off over night. A fridge is generally well insulated and if kept closed should keep the temperature fairly well. Not to mention, I have quite a few gallons of very cold beer in the fridge to help keep the temperature steady as well.
Lo and behold... in the morning, the temperature had gone up. But only by 2-4C... in 6 hours. The warming had allowed the yeast to get active. But I still kind of monitored the fermometer and let it slowly rise until about 16-18C. 18C is supposed to be fairly ideal for most ale yeasts, including the US-05 strain I had going.
Now here is where the science kicks in. 2-4C in 6 hours is fairly slow. But getting up to 16-18C took even longer. And it basically held at 18C without any power for almost 12 hours after it got there. And the reason is actually quite simple (or maybe not). When the fridge and the beer were at the coldest, they were also at their greatest temperature differential from the ambient temperature in my office. The greater that difference, the quicker the fridge will warm up. The greater the temperature difference in the fridge, the quicker the beer will warm up.
With the fridge off, it gradually got closer in temperature to the ambient temperature outside of the fridge. As that happened the rate at which the temperature increased slowed. The same effect also happened in the fridge between the ambient internal temperature and the beer temperature.
Also, the 4-ish gallons of beer is quite a large volume of liquid to drastically change the temperature in without wild differences in ambient temperatures.
Where is this all going? Well...
Firstly, it isn't anywhere near as easy as anyone would have you to believe to rapidly change the temperature of a sizable batch of fermenting beer. This is probably why swamp coolers are popular (and generally effective). No one will convince me otherwise, that as the ice bottles or whatever they use to cool warm up and melt that the temperature doesn't rise more than a few degrees before topped back up. Not to mention the water would have "cold spots" and "warm spots", and the yeast unless completely wrapped in cold spots, would probably occupy a warmer area in the water.
And secondly, with the exception of some non-temperature controlled, heat extreme locations, ideal fermentation temperatures (for ales) are going to closer to room temperature than they are to refrigeration temperatures. This means that manual temperature control (IE... turning the fridge off every few hours once you get at/near your target temp) will probably result in a fairly stable fermentation. If you can remember to cool it a bit longer before you go to bed, you can likely even keep it in that range overnight without worry. Will depend of course on ambient temperature differences between the house and fridge, as well as how well insulated the fridge is.
As usual, this isn't to try and say that proper temperature isn't better. I have zero doubt that a perfectly maintained temperature (whatever that means) will stress the yeast less than gradual temperature changes. Also, a temperature control module takes the fussing out of your hands. You don't need to watch for when you start getting to the temps you want, and you don't need to manually do anything to keep it there.
Just saying that is may not be as big a deal as some would have you believe. This second batch I'm doing has never fluctuated more than 1C every 2 hours and most of the time temperature "swings" were FAR slower than that. I'm fairly confident it will out come tasting much better than my room temperature fermentations of past. I'll probably do a short diacetyl rest as fermentation slows down. But not too worried in general since it is actually fermenting most of the time in/around that 18C mark, but also because I bottle condition.
I'll probably either update this or make a new post once these two batches are drinkable. (Assuming the first batch ever is).
As mentioned, I bought a wine cooler with a supposedly near high enough max temperature (14C) for ale yeast. As many will point out, fermentation is exothermic and actual fermentation temperatures can push that temperature up even further inside of the fermenter. So I was hopeful that this 14C would effectively be closer to 16-18C inside of the fermenter. 18 would be ideal, but most people had good results with 16C for many yeast strains.
I don't have a temperature control module yet. Though I will probably get one at some point. For now, I just have an analog meat thermometer in there. Just sitting on top of my fermentation pail.
The first batch I put in, I think probably had a stalled fermentation. I panicked a bit, when after 24 hours, there was absolutely no activity. So I went and pitched another packet of yeast. It got started after another 12 hours, but seemed sluggish and only went on at a slow pace for a few days. Now, because I added the second pack, another option is that it took off like a rocket while I wasn't looking. It wasn't a high gravity beer. So seems possible. Anyway, temps at the top of the fridge reported a chilly 10-12C, which means that down near the bottom was probably even colder. This is why I'm thinking it possible that the yeast just fell out of suspension and I'll have a disgustingly sweet beer to deal with. Anyway, I bottle on Saturday, will have a better idea then.
To try and figure out what was going on a bit more, I picked up some fermometers. Those peel and stick thermometers for the fermentation pail. The second batch I did things a little differently and paid a lot more attention.
Keep in mind, if that first batch is ruined, it is because I let I things get WAY out of the acceptable range and fermentation never had a chance to get fully started. Also keep in mind, I'm not even sure if I screwed up that batch yet. Beer making IS pretty darn forgiving. But fermenting in a fridge that is actually pushing fridge like temperatures (with an ale yeast) is quite a big no-no. :)
Second time around I properly aerated the wort. I usually do. The first wine cooler batch I didn't for some reason. The next thing I did was watched the fermometer at regular intervals to get an idea how quickly or slowly the temperature was changing and roughly where it was at.
Given the paranoid ramblings of virtually everyone on the forums I was a little concerned with what I did next. But I noticed after 24 hours that the fermometer was dropping to levels I wasn't happy with... so I shut the fridge off over night. A fridge is generally well insulated and if kept closed should keep the temperature fairly well. Not to mention, I have quite a few gallons of very cold beer in the fridge to help keep the temperature steady as well.
Lo and behold... in the morning, the temperature had gone up. But only by 2-4C... in 6 hours. The warming had allowed the yeast to get active. But I still kind of monitored the fermometer and let it slowly rise until about 16-18C. 18C is supposed to be fairly ideal for most ale yeasts, including the US-05 strain I had going.
Now here is where the science kicks in. 2-4C in 6 hours is fairly slow. But getting up to 16-18C took even longer. And it basically held at 18C without any power for almost 12 hours after it got there. And the reason is actually quite simple (or maybe not). When the fridge and the beer were at the coldest, they were also at their greatest temperature differential from the ambient temperature in my office. The greater that difference, the quicker the fridge will warm up. The greater the temperature difference in the fridge, the quicker the beer will warm up.
With the fridge off, it gradually got closer in temperature to the ambient temperature outside of the fridge. As that happened the rate at which the temperature increased slowed. The same effect also happened in the fridge between the ambient internal temperature and the beer temperature.
Also, the 4-ish gallons of beer is quite a large volume of liquid to drastically change the temperature in without wild differences in ambient temperatures.
Where is this all going? Well...
Firstly, it isn't anywhere near as easy as anyone would have you to believe to rapidly change the temperature of a sizable batch of fermenting beer. This is probably why swamp coolers are popular (and generally effective). No one will convince me otherwise, that as the ice bottles or whatever they use to cool warm up and melt that the temperature doesn't rise more than a few degrees before topped back up. Not to mention the water would have "cold spots" and "warm spots", and the yeast unless completely wrapped in cold spots, would probably occupy a warmer area in the water.
And secondly, with the exception of some non-temperature controlled, heat extreme locations, ideal fermentation temperatures (for ales) are going to closer to room temperature than they are to refrigeration temperatures. This means that manual temperature control (IE... turning the fridge off every few hours once you get at/near your target temp) will probably result in a fairly stable fermentation. If you can remember to cool it a bit longer before you go to bed, you can likely even keep it in that range overnight without worry. Will depend of course on ambient temperature differences between the house and fridge, as well as how well insulated the fridge is.
As usual, this isn't to try and say that proper temperature isn't better. I have zero doubt that a perfectly maintained temperature (whatever that means) will stress the yeast less than gradual temperature changes. Also, a temperature control module takes the fussing out of your hands. You don't need to watch for when you start getting to the temps you want, and you don't need to manually do anything to keep it there.
Just saying that is may not be as big a deal as some would have you believe. This second batch I'm doing has never fluctuated more than 1C every 2 hours and most of the time temperature "swings" were FAR slower than that. I'm fairly confident it will out come tasting much better than my room temperature fermentations of past. I'll probably do a short diacetyl rest as fermentation slows down. But not too worried in general since it is actually fermenting most of the time in/around that 18C mark, but also because I bottle condition.
I'll probably either update this or make a new post once these two batches are drinkable. (Assuming the first batch ever is).
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