Fermenting a couple of beers at once - getting the temp right

[TK1]

Hi,

I currently use an old fridge to ferment in, and it has space for two fermenters. Usually with one going I mount the temperature probe on the side of the fermenter, covered by a piece of foam. So I seem to get a pretty accurate reading for the temp controller off the vessel.

However, I was keen to know what others do if you have two fermenters going at once, with different brews inside - especially if they are put in a few days apart, so not necessarily cooling down at the same rate. I'd put in complementary brews in terms of temperature, e.g. two ales or an ale and cider fermenting at around 18 - 19 degrees.

Hanging the temp probe just in the fridge would seem to give a more general reading, and possibly not accurate if it's reading just the fridge temp.

So interested in any experiences or thoughts on how others get around this. Do you just set the temp a few degrees lower, or attach it to the hottest/newest fermenter?

Thanks!

 

[TheWiggman]

Depending on what you're fermenting and how quickly it's going, I would use the stick-on method and transfer to the new fementer when it's put in. During the first phases of fermentation the temperature is far more critical. Hence, if you get the temp right for the first fermenter for the first 3 days, get halfway to your FG, and put the new fermenter in there will be minimal (if any) impact on the first beer. Obviously this can't apply to a saison and lager in the same fridge.
Don't use the dangle-in-the-air method, there can be quite a difference between the air and fermenter especially during a rigorous ferment. Likewise if you put the sensor in a bottle of water inside the fridge.

 

[Tilt]

I've done this a couple of times when I needed to fill a gap in the kegs - at best I got average results.
I matched yeast temp ranges, had similar starting gravities, pitched at the same time and even added a computer cooling fan to prevent Temp stratification +!swapped the fermenters around (top to bottom and vice versa). I strapped the probe to the most active ferment beer thinking that it was high temps I'd want to control rather than lower ones in the first 72 hours.
In the end each time I've done this neither beer has turned out as good as when I concentrate on one ferment at a time - driving temps and managing the profile specifically for that beer.
Long story short - you get twice the amount of beer in the same timeframe but not at the highest level of quality.

 

[themonkeysback]

I have done this quite a few times.

Unlike tilt I haven't really noticed any deterioration in beer quality.

Depends a little on the set-up of your fridge I guess.
My fermenting fridge is big enough that I can fit two 30L fermenters side by side. Obviously things are different in a fridge where they are above and below each other.

In general if starting both ferments at the same time I either just wedge the probe between the two fermenters (if using 2 of my plastic ones) or have the probe inserted inside my small chronical if using it + 1 plastic fermenter. Similar to your suggestions in the OP I have done 2 lagers at the same time/2 ales at the same time (with the same, and with different yeasts) and generally it has been fine.

Things become a little more complicated if you are starting ferments several days apart.
Fermentation will produce heat, and the most active fermenter will be producing the most heat.
So say if you are doing 2 ales - generally I would have the probe attached to the first fermenter, and then change it over the the new fermenter when I put it in the fridge. The only issue with this is the fridge may get colder to control the temp of the 2nd ferment and may drop your first fermenter by a degree or two. Another option is start your initial ferment a little lower (say 16 degrees) then increase to 18 once you add the new fermenter (with the same switch of probe location).

If you are considering diacetyl rests again it becomes more complicated, as you can't be quite as particular about starting at a particular SG because it is unlikely it will be the same in both vessels. Generally I just pick a middle ground I am happy with. If doing 2 lagers I will generally do my diacetyl rest once the beer added last to the fridge/the slowest fermenter is nearing terminal gravity. Generally the first beer will already be at terminal gravity by this point and pedantic brewers would suggest this isn't the best approach for a diacetyl rest but I have found it works adequately with my set-up.

I also have a fan in my fridge to try and stabilise the temp etc.

Hope that all makes sense/helps.

Adam.

 

[n87]

I have fermented 2 identical beers at once.

had the probe on the top one (which was hotter due to the heat rising thing)
the bottom one took a little longer ( a day or so) to ferment out... but apart from that... no differences in taste or quality

This was a Pale Ale fermented with US05, so a couple of degrees cooler wouldn't hamper it.

 

[Diesel80]

Same as above, strap to the one with most aggressive yeast. In my case normally the Nottingham fermenting one.

If you seals are buggered in the fridge, swinging in the air will have the compressor kicking on and off too often.

Cheers,
D80

 

[mosto]

I can fit two 20L cubes (which I ferment in) in my fridge very snuggly. If I've only got one in, I hang the probe in the air near the fermenter. Not best practice I know, but a bit of experimenting has shown to me that rigorously fermenting wort will ~2c higher than the ambient temp so I set the STC 2c below desired temp to compensate. If I've got two in there, I wedge the probe between the two to get an average reading. Again, would not be 100% accurate but would be out 2c at the most (and probably less). So I use yeasts with similar temp ranges and ferment in the middle of that range.

 

[Moad]

I do this with a couple of smaller fermenters and my conical. I usually put my favourite beer in the conical and look after that one, let the others run wild. Obviously not ideal but gets it done if you are looking to fill kegs quickly

 

[rude]

I no chill so put cubes in before hand to get to desired ferment temp

Sometimes 2 c lower then raise as they ferment

I just stick to the side of either fermenter close enough for me

 

[AJS2154]

Hi TK,

I made a schwarzbier and a bohemian pilsner side by side this year in my fermenting fridge. I used 2 different lager yeasts and used the temperature probe from my STC1000 on the stainless fermenter. The probe was covered in bubble wrap on one side, then had gaffer tape over the top. I had the temperature set at 12 degrees.

Whilst the beers seemed to ferment at slightly different rates, they mirrored each other reasonably. When fermentation was over, I lagered them in the fridge at 2 degrees for 3 weeks. I did not move the probe from start to finish.

The beers finished off nicely, I was happy with the results. It can work, from my experience. I will do it again next winter.

The hardest part of this is approach was the long brew day.....fermenting was easy after that.

All the best, Anthony

 

[thylacine]

No worries. For over 170 brews now I have used a little 150L chest freezer attached to a temperature controller for my four fermenters. Always four different recipes. (i.e. 4 ales OR 4 lagers) Not always same yeast. My taste buds remain happy. NOTE: I usually ferment at yeasts' lower range and assume fermenters with active krausen are at least 2c warmer than the temp gauge indicates.

Cheers

 

[TK1]

Hi,

Thanks all for the replies and experiences. Looks like the consensus is it's doable, with some experimenting and thought about where to take the temp reading from and maybe adjust it down a bit - and ensuring the styles are complimentary.

Will give it a go - worst case scenario is a "learning experience" and the need to do another brew

Out to the shed then for some brewing on the weekend...

 

[AJS2154]

Hey thylacine......that is impressive mate. Can you tell me just how you manage to have 4 different brews going all at once? Do you brew them all on the same day? How does it happen?

 

[thylacine]

Hey thylacine......that is impressive mate. Can you tell me just how you manage to have 4 different brews going all at once? Do you brew them all on the same day? How does it happen?

One of the advantages of 'No-Chilling'. Once I have four cubes filled and at the temp for the yeast, they are all pitched.

e.g. a brew (or sometimes two) per day; each cube set aside at ambient for 24hrs then placed in fermentation chamber to achieve desired yeast temp; when fourth cube is at desired temp then all are pitched.

I ferment in the same cube. Minimum 2 weeks Ales & 3 weeks Lagers. Gradually reduce temp (3c per day) down to 1c for minimum 7 days.

Cheers