Hey guys,
I’m brewing my first lager, a Munich Helles, using saflager W34-70 yeast and im worried my fridge temperature is too low. It’s about 43 degrees at minimum setting and saflager recommends minimum of 45 degrees. Should I worry? I’m might try turning my fridge on and off to get a temperature a little higher. Also, should I try doing a diacetil rest in those conditions?
Thanks in advance
With the fridge at 43°F, the fermentation temp will be easily 51°F. (Fermentation generates heat.) So you’re good. You can reduce diacetyl (not a big problem with 34/70), and just speed up fermentation, by raising the temperature at the later stages. If you can’t control temp, you can just wait until you are at or under 50% of OG, and just move the fermenter to a cool room temperature, like a basement. All the temperature-sensitive flavor producing effects happen earlier in fermentation, this won’t make it taste ale-like, just clean it up and finish it off faster.
Wait, the lowest your fridge will go is 43*? Are you talking about crashing the beer afterwords and lagering, or just the primary fermentation? You say 43* at minimum but you can ferment w34-70 from 48-68*.
I have a Munich helles going right now, same strain. I fermented at 58* and then crashed to 38* after 3 weeks. I did not do a diacetil rest, just not worried, but the beer has been at 38* for about a month now.
Just looking to clarify.
And I would also go for an over pitch with a lager strain.
I thought the OP meant the lowest degree of attemperation he could get, ie the lightest touch on the thermostat, or the highest fridge temp, would be 43°F. Otherwise the question makes not much sense.
Yea I know but he’s worried that’s too low, and it’s the minimum… so? That’s why I’m wondering about not being able to crash The temp. After the fact.
If anything I would want to ferment higher than 43 or 45. But that’s just me, and then I’d still cold crash later.
Maybe there is some confusion between fermenting and the lager process was my take at the OP.
This may sound crazy, but a steady 43F would be better than bouncing up and down. I’d do 43F and keep an eye on it. When activity slows, if you can warm it up and keep it warm, great. But avoid drops in temp, especially as you get past half way done.
If 43°F is his top end on ambient in the fridge, he should have no trouble with that. Warm it up as fermentation winds down, then back in the fridge to crash near freezing or below. I think that’s what I recommended. What I’d do.
Me too. 43 fridge for 4 or 5 days, then to the most stable temp area I had. Maybe closet in center of house, till terminal gravity and no diacetyl. Then back to the 43 fridge for a week, fell fine, keg a week later.
Good point, Jim, on STABLE temp area once you start letting it rise. I said basement, but I know this time of year my basement can fluctuate. Your closet idea is better. Stability is more important than actual temp.
Hey guys sorry for the confusion, what I meant is my fridge at minimum power stays at about 43 (which is too cold for w34/70) and that got me worried. I think you guys got me covered. I’ll probably just keep it like that, ignore the rest (since it’s summer right now so I won’t have a chill room in my house) and lager at 40ish when fermentation is done.
That should work! If the fridge is at 43°F, fermentation will go at around 51°F or so, and when it winds down and produces less heat, the beer will eventually come to the temp of the fridge, so you can even run the fridge a little colder for lagering, keeping it in the fridge the whole time. Just don’t reduce the temp the fridge is set to until you’re sure fermentation is complete.
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.
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.)
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.
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)?
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.
Fermentation seems to be going well so I’ll leave it like it is. I’ll keep you posted! Thanks for the advice