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Author Topic: Brewing a lager but can't quite control the temperature  (Read 5104 times)

Offline Robert

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Re: Brewing a lager but can't quite control the temperature
« Reply #15 on: March 13, 2018, 02:14:00 pm »
But if his fridge holds 43°F, he doesn't need to do anything else! Fermentation adds 8 degrees or more, so he will be running at the perfect temp.  If he shuts off the fridge or adds heat, he will run the temp too high.  As fermentation winds down, is the time to cut attemperation. The OP just seems to have been concerned that the recommendation of >48°F referred to ambient, not fermentation temp.  I hold my fermentation chamber at 45°F, but I like to run 34/70 a little warmer at 54°F.  (Then up to 64°F at the end.)

I would guess that if you ferment at 43, the fermentation won't be active enough to generate 8 degrees.

I used to pitch that low for absolutely no good reason.  I recall the lag time was longer, but otherwise it got going and ran normally after that.  An extra pack of yeast to make up for lower growth could be insurance if you have to pitch on the low side.
Rob Stein
Akron, Ohio

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Offline ynotbrusum

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Re: Brewing a lager but can't quite control the temperature
« Reply #16 on: March 13, 2018, 02:21:49 pm »
I routinely ferment at 46F - no problems and not much lag, as long as a healthy yeast pitch is made.  I have not measured the differential in terms of the wort in active fermentation in my fermenter chest, but I would be surprised if it rose to anywhere near 8 degrees.  Ales, maybe if in the low 60's, might get that kind of differential, but lagers in the 40's seems a stretch - I could be dead wrong and am willing to be convinced otherwise.  Robert, you have a thermowell at the bottom of your Spiedel, so is that measuring such a large temperature differential (ambient to actively fermenting wort being 8 degrees different)?
Hodge Garage Brewing: "Brew with a glad heart!"

Offline Robert

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Re: Brewing a lager but can't quite control the temperature
« Reply #17 on: March 13, 2018, 02:30:17 pm »
Yep, I'm getting 8°F measured in the thermowell.  46°F ambient, 54°F ferment.  I used to use a stick on liquid crystal thermometer on my glass carboy, and that only showed 6°F difference.  I always assumed the actual difference measured in the ferment instead of at the interface with the environment would be higher, and it is.
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline Adam

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Re: Brewing a lager but can't quite control the temperature
« Reply #18 on: March 13, 2018, 03:50:55 pm »
Here is a suggestion:  Put the fermenter in at 43 and unplug the refrigerator and don't open the door.  If ambient is 50's or so, it should stay pretty stable and may rise up to 50, but may not.  You can always plug it in for "short stints" to control the internal temperature of the fridge and prevent big swings of the fermenting wort itself, if ambient is a lot warmer where the fridge is at.  A water bath in the fridge with the fermenter in the water bath is another solution if there is room...I keep a small laundry tub for use with my ales in the summer and swap out frozen water bottles to keep things in the low 60's in my basement and swap out the water, if it rises too much during fermentation.  That same concept would work for lagers in a fridge, I should think.

My thinking is that as the fermentation slows and he needs to raise the temperature for VDK rest or to just bring temp up to finish ferment he can plug in the heater for a few hours then unplug it

Before I had a temperature controller for both hot and cold I would set my fridge to the cold setting I wanted and then wrap my fermentor with an aquarium cooler and plug that in when I wanted the beer to warm up. The fridge does have to work a little bit extra but it can allow you to slowly warm your beer back up.

Let us know how your final product turns out.




But if his fridge holds 43°F, he doesn't need to do anything else! Fermentation adds 8 degrees or more, so he will be running at the perfect temp.  If he shuts off the fridge or adds heat, he will run the temp too high.  As fermentation winds down, is the time to cut attemperation. The OP just seems to have been concerned that the recommendation of >48°F referred to ambient, not fermentation temp.  I hold my fermentation chamber at 45°F, but I like to run 34/70 a little warmer at 54°F.  (Then up to 64°F at the end.)
Fermentation at Elevation

Offline itsjoao

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Re: Brewing a lager but can't quite control the temperature
« Reply #19 on: March 13, 2018, 04:56:14 pm »
Fermentation seems to be going well so I'll leave it like it is. I'll keep you posted! Thanks for the advice

Offline itsjoao

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Re: Brewing a lager but can't quite control the temperature
« Reply #20 on: April 06, 2018, 05:28:08 pm »
Just to inform you all, I just bottled today after 3 weeks of lagering at 4 degrees celsius, and dyacetil seems to be suuuper high. Smells a lot like butter, and i just bought a temperature controller for my fridge hahaha.
Cheers guys, thanks for the help