Fermenting Temperatures (in A Fridge)

[beerguide]

I am in the process of testing my used fridge out for the first time as a fermenting (primary) fridge. The fridge itself doesn't work properly and never gets colder then 7 degrees, even overnight.

I'm reading and being told a large variety of conflicting information regarding temperatures and I'm hoping for a more definitive response from everyone here. Below is a quick summary of what I've read and believe to be correct.

For Lager:
I should aim for around 10-15 degrees for primary fermentation.

For Ale:
I should aim for around 18-24 degrees for primary fermentation.

Are these correct? As I'm now looking for a Fridgemate I've seen a few posts from people saying they are fementing at 5 degrees, I would have thought this would be too cold for even a Lager and the yeast would become dormant. Am I reading this wrong, and are they most likely cold conditioning a secondary fermentation?

Im putting down a Pale Ale in the next day or two and I've worked out (until my fridgemate arrives) that if I cool the fridge for around 10 minutes in the morning it holds around 16-18 degrees all day without needing to be turned on again. The yeast I have S04 SafAle which should be okay by reading the packet if I can hold a temp around this.

I tried searching for the answer to this here, but became more confused as there are many 'recommendations' on what temps are acceptable. I've even been told I could ferment at 7 degrees for my Ale by just leaving the fridge on permanently. I hope to get a more definative answer in this thread before I go and stuff up totally

I know this has been discussed probably a million times and I apologise for another thread, but there are so many conflicting answers when I search these boards and I wouldn't be confused if it weren't for this fridge as I'd just do it at room temp which is around 20 degrees.

 

[gavpk]

i ferment my ales at around 18-20, (i think u were told wrong as 7c is a bit low for ales) i only use the fridge in the summer when the days are hot, any other time i have no probs keeping 18-20 with a heater. remember this is only for ales. lagers you will need your fridge most of the time to keep a nice 11c

hope this helps

cheers

Gav :beer:

 

[Wortgames]

The temps you quoted are perhaps a bit on the warm side. That is great if you are just beginning and/or you want relatively quick results, but a lot of people ferment a lot cooler than that.

Some lager yeasts are active at 2C, although they will take many weeks to ferment out at that temp (as is traditional). True lagers are usually fermented anywhere between about 3C and 12C and ales are fermented between about 14C and 24C.

If your fridge doesn't get very cold it is probably low on gas, which means it will be very inefficient and therefore expensive to run. Used fridges aren't hard to come by these days, I would say recycle yours and get one that works (or even one that has a busted thermostat) and use an external controller. Relying on a faulty fridge to provide fermentation temps is not good for the environment or your wallet.

 

[beerguide]

Cheers Gav! Thats what I thought too and were it not for the fridge I would have always thought that.. I just got totally confused once I started looking into controlling the fridge and I saw a lot of conflicting info and advice.

Does the fermentation process itself generate much heat? All the temp readings for my fridge have been made with an empty fridge, I'd imagine the heat generated by fermentation would only be a degree or two in the fridge, but need to take that into account obviously.

Ambient temps are mid to high 20s here at the moment and we had over 30 at the weekend, so I'm going to need the fridge I think.

Wort: The time to ferment doesn't bother me if it takes longer, I'd prefer to do as much 'right' as I can even if it does take longer. Thanks for the info - I'll get the fridge checked out as its only about 3 year old.

 

[gavpk]

wortgames is right, look at another fridge maybe, and also mashmaster (site sponser) sell the fridge controllers, i got one from there and it works a treat.

good luck

Gav

 

[beerguide]

Wortgames, just rereading your post you say 'true lagers'. Can you elaborate on this a little further, and where do I find a suitable yeast for this as most of the Lager yeasts I've seen all have around 9 degrees as the lowest ideal temp (eg: S23 Saflager)?

Is this just because its harder to reach and they advertise a higher temp as most people can acheive this, I just don't want to have the temp drop too low and the yeast go dormant on me?

Fermenting lagers around 5-7 degrees for a lager to me would be perfect for the fridge at present. Noting above when I said 7 degrees, that is on the fridge's lowest setting, not the normal setting. On the 'normal' the fridge gets down to around 3, and high its around 2.

 

[Wortgames]

Traditionally, lagers were brewed in caves full of ice. The yeast mutated and only strains that could tolerate the low temps survived, and became 'lager yeast'. They took months to ferment and the beer was ready to drink by summer. This is a bit impractical for most modern brewers (and there is the issue of diminishing returns) so few go to these lengths any more, but most lager strains will happily ferment at quite low temps.

The lowest temp I ever fermented a lager at was around 6C, and it took about 8 weeks from memory (I think it was a Bohemian Pilsner strain). It was a lovely drop but I don't think it was any better than ones I've done at 10C which are ready in half the time.

 

[simpletotoro]

For Lager:
I should aim for around 10-15 degrees for primary fermentation.

For Ale:
I should aim for around 18-24 degrees for primary fermentation

hi...id go with these temps instead...

For Lager:8-12/c
For Ale:16-20/c (16/c cause like you said the fermentation generates some heat on its own...)

also

The yeast I have S04 SafAle which should be okay by reading the packet if I can hold a temp around this.

i'd use us-56 or s-05 or whatever they call it these days for a pale ale as it ferments cleaner then s-04 ...i use that one only for stouts and dark ales ...up to you though...

Im putting down a Pale Ale in the next day or two and I've worked out (until my fridgemate arrives) that if I cool the fridge for around 10 minutes in the morning it holds around 16-18 degrees all day without needing to be turned on again..

you could also bung in a couple of frozen 2litre water bottles into your fridge to help make sure your temp doesn't rise above 16-18/c if the day turns out to be a scorcher ...i do this in my other dodgy fridge and it works a treat ...but the main fermenting fridge has temp control ...

don't stress if the temps drop below what your after it'll just slow down or stall temporarily the ferment ...as you no doubt know the real killer is to much heat....

 

[Wortgames]

Just another note on yeast temps, there was some discussion a while back about exposing the yeast to falling temps. The theory was that the yeast go into 'uh-oh, winter's coming' mode and start taking measures to protect themselves rather than continuing to ferment.

Basically if you plan to ferment cool, you should start off cool, not start warm and then chill which can trick the yeast into premature hibernation.

I'm sure someone will correct me if this has since been debunked but it sounds reasonable to me.

 

[simpletotoro]

Just another note on yeast temps, there was some discussion a while back about exposing the yeast to falling temps. The theory was that the yeast go into 'uh-oh, winter's coming' mode and start taking measures to protect themselves rather than continuing to ferment.

Basically if you plan to ferment cool, you should start off cool, not start warm and then chill which can trick the yeast into premature hibernation.

I'm sure someone will correct me if this has since been debunked but it sounds reasonable to me.

yeah this sounds very feasable to me but what actually happens when they hibernate?...
i'm not saying what your saying is wrong in fact it sounds very logical...
but i have on the odd occassin actually frozen my newly fermenting wort and yeast and just slowly thawed it out over several days and gently swirled the fermenter and she started up right as rain...the result tasted pretty damn good as well ...mind you i do have a gutter palate

anyway i ramble off a little ..my question is when the yeast goes in hibernation mode can any off flavours or ill effect result or is it just a case of sleep time...
cheers simpletotoro

 

[beerguide]

Basically if you plan to ferment cool, you should start off cool, not start warm and then chill which can trick the yeast into premature hibernation.

Makes sense. Thanks again to both yourself and simpletotoro for your input, it is appreciated. As I continue to learn and try different yeasts and temperatures etc.. it will all become much clearer and I'll wonder why I was ever in such a confused and worrisome state

 

[Wortgames]

my question is when the yeast goes in hibernation mode can any off flavours or ill effect result or is it just a case of sleep time...

I'm not aware of any ill effects occurring purely from yeast going into hibernation, AFAIK slower colder ferments just tend to result in 'cleaner' tasting beers with less yeast character - but I guess the thought of the good yeast going night-night leaving other bugs to have the run of the place is probably enough to make it less than ideal.

 

[KGB]

Does the fermentation process itself generate much heat? All the temp readings for my fridge have been made with an empty fridge, I'd imagine the heat generated by fermentation would only be a degree or two in the fridge, but need to take that into account obviously.

I was going to mention this when I read in your first post that the fridge will hold 16-18 deg all day when turned off. I'd expect the fermenter to add a few degrees over the course of a day if it was in a fridge that was turned off.
If you have to ferment when its hot, a wet towel wrapped around the fermenter and some airflow (window or small fan) works wonders to keep the temp down. I've been doing this the last few days in Sydney (30+ the last few days) and have been amazed how well it works.

 

[beerguide]

I've found pretty much the same that the fridge is holding around 16-18 on its on, even on the recent 30+ days we've had in Newy.

I've been occasionally whacking in a 2ltr bottle full of salt-water (frozen) in the fridge during the day and I have a digital thermeter which will record flucuations in temperatures and its been maybe a degree or two +/-so its been a great technique/trick.

Thanks KBG.

 

[frogman]

I hope with your digital thermoteter you are measuring fermenter temps not ambient temps in the fridge.
I found when I first set up my fermenting fridge my fermenter temps were nearly 10deg higher than the air temp in the fridge. Now keep fridgemate probe taped to side of fermenter with a block of foam over it to insulate it from temp flucations when the door is opened to sniff the air lock.

FROGMAN...

 

[beerguide]

Frogman, certainly am I too have the probe inside a foam block which is taped to the fermenter. I actually have two digital probes on the fermenter - one on the top and one on the bottom (why? cause i had one spare so I thought I might as well use it). I also have the usual stick on one also - you know the cheap ones you buy from big-w etc..

There is around a two degree difference between the fermenter and ambient temp in my fridge - its a reasonably small fridge.

But very good advice for anyone else reading this thread who may not have thought of it.

 

[blackbock]

Just regarding the self-generation of heat during fermentation: it is my experience that a normal pitching quantity does not appreciably raise the temperature of the wort, but when an excess of yeast is available (i.e pitching onto an old cake) the wort temperature can easily be 2-4 degrees above ambient. I am speaking about a standardish batch size of around 22L.