Lagering, temperature control, yeast activity.

[ol-hazza]

So i made a pilsener 6 odd weeks ago, which i fermented in a swamp cooler and tried to keep around 12c. Since then i have aquired a second fridge which i wired an stc 1000 to with the help of some great threads on here.

Naturally before i had wired in the temp control i put my pilsener and an amber ale in the fridge and froze them both solid, which was fun. The amber has since been bottled as it looked like it had enough yeast still to carb it up. Will let yall know how that goes in a month or so.

So anyway now the temp control is working, i decided to get it lagering at 4c. Got it programmed and narrowed in from the default .5c variance to .3c. The sensor i placed in a wine bottle full of water as i figured that would end up around the same temp as the beer which is at FG.

The next day i checked on it and it was still reading as 16c, which was a but confusing until i realised that i hadnt turned on the switch for the fridge on my stc setup. DOH!

Anyway i switched that on and a day later checked it out again. This time it was reading 4c for the wine bottle, but a seperate reading on the beer showed that it was at 10c. I realised that during fermentation the beer would stay warmer than ambient in the chamber but didnt think it would remain that much higher so late in the play.

So next step was to fasten the temp controller to the beer under some styrofoam/polystyrene stype stuff. The beer is now reading at 4.5c which is good, but the water in the wine bottle has frozen.

So the beer is remaining 5 - 6c above ambient (provided the stc is reading accurately) is this more likely to be yeast activity, incorrect temp readings, magic, the bigger container?


Luckily i decided against lagering and cooling bottles at the same time and saved myself that mistake. Or would they have been fine for the same reason the pilsener is?

 

[ol-hazza]

Bump

 

[aryoung1980]

To me it sounds like it's a volume issue. Your 750mL bottle of water will cool down much quicker than 19L of pilsener. When you strapped the probe to the beer, it probably sent your cooling unit into high gear...dropping the ambient temp to 0C or lower which caused your freezing.

That's my two cents. Maybe someone else has a different idea.

 

[ol-hazza]

I was thinking that was probable but as more time passes and the temps of the vessels remains different that would suggest to me that there is still some yeast action creating heat in the lager?

 

[estricklin]

To me it sounds like it's a volume issue. Your 750mL bottle of water will cool down much quicker than 19L of pilsener. When you strapped the probe to the beer, it probably sent your cooling unit into high gear...dropping the ambient temp to 0C or lower which caused your freezing.

That's my two cents. Maybe someone else has a different idea.

Which is why unlike many others on this forum, I don't always place my sensor on the fermenter, but rather on the top of it loosely, or against the walls of the deep freeze itself. If there's a big temp difference at the start, you can actually get things a little too cold by placing the probe on something with such a large volume.

 

[ol-hazza]

Which is why unlike many others on this forum, I don't always place my sensor on the fermenter, but rather on the top of it loosely, or against the walls of the deep freeze itself. If there's a big temp difference at the start, you can actually get things a little too cold by placing the probe on something with such a large volume.

So after the initial temperature drop you then fix it to the fermenter or do you brew/lager to ambient temp?

 

[shtoive87]

Which is why unlike many others on this forum, I don't always place my sensor on the fermenter, but rather on the top of it loosely, or against the walls of the deep freeze itself. If there's a big temp difference at the start, you can actually get things a little too cold by placing the probe on something with such a large volume.

I would think there's enough heat leaking into the fermentation chamber that you don't have to worry about things staying too cold. You want to keep the beer at fermentation temps, not necessarily the chamber itself.

To the OP: you may have the wine bottle in a colder part of the chamber. The water will cool off sooner than the fermenter due to the mass difference (much like a drop of water cools faster than a pot of water). I think you did save yourself some trouble by lagering the bottles elsewhere.

 

[ol-hazza]

Which is why unlike many others on this forum, I don't always place my sensor on the fermenter, but rather on the top of it loosely, or against the walls of the deep freeze itself. If there's a big temp difference at the start, you can actually get things a little too cold by placing the probe on something with such a large volume.

This makes sense, but after the initial temp drop do you then affix the probe to the fermenter or do you lager/brew by controlling the ambient temp?

 

[estricklin]

This makes sense, but after the initial temp drop do you then affix the probe to the fermenter or do you lager/brew by controlling the ambient temp?

My chest freezer is pretty big, so what I do is place the fermenter just a half inch or so from the walls and sort of fix the probe between the 2 or as I mentioned, on top of the bucket, because then the volume isn't effecting it much it's just touching the thin lid which should see temp changes quicker.

 

[ol-hazza]

Ok. So roughly what temp would you set the fermenting chamber at when brewing ales or lagers?

 

[estricklin]

Ok. So roughly what temp would you set the fermenting chamber at when brewing ales or lagers?

With lagers I'm not as scared of starting too low, I mean I've started as low as 45F and ramped up, but I generally go about 52-54. For ales I set it to about 67, sometimes I do see it drop as low as 65 but it's almost always 66-68 so +/- 1 degree. When I lager I set it for 34 or so but I've gone as low was 30 just keeping an eye on things.

Edit:

Oh and a tip, I done this in my kegerator but not in my fermentation chamber as I need to, I made a recirculation fan out of a small plastic coffee can and an old computer fan and cell phone charger. Keeping the air moving makes a huge difference in how well you can maintain a constant temperature.

 

[ol-hazza]

Yeh a fan is on my to do list, I have only recently gotten the STC wired in.

Im also going to put a fermenter bucket of water in the chamber to see how that compares with my beer temp, and then do a top/bottom switch as well. This fermentation chamber build is more complicated than I thought!