Multiple Fermentations - One Fridge

[Benniee]

I've recently upgraded my fermentation fridge due to the old one carking it, and the new one I've got will comfortably fit in a couple of fermenters. Great - this will allow me to get some more beer brewed in a shorter period of time.

But in thinking about it I've come across a problem I'm wondering how others deal with. Lets say I am currently fermenting a lager in my fridge at around 10 degre, and I want to get another beer underway. Going through my regular brew day I end up with beer in the fermenter at around 25 degrees. What I would typically do is put the fermenter in my fridge to chill it to pitching temps, then pitch as normal. But if my fridge currently has a fermentation underway when I go to do this it will likely raise the temperature of the currently fermenting beer while the second beer cools to pitching temps. Assuming both beer are equal volume this temp swing could be half the difference of the two.

So when people are fermenting multiple beers in the one fridge how do they deal with this? Brew two beers close together and then wait until both are at picthing temps before pitching any yeast?

Benniee

 

[QldKev]

I've recently upgraded my fermentation fridge due to the old one carking it, and the new one I've got will comfortably fit in a couple of fermenters. Great - this will allow me to get some more beer brewed in a shorter period of time.

But in thinking about it I've come across a problem I'm wondering how others deal with. Lets say I am currently fermenting a lager in my fridge at around 10 degre, and I want to get another beer underway. Going through my regular brew day I end up with beer in the fermenter at around 25 degrees. What I would typically do is put the fermenter in my fridge to chill it to pitching temps, then pitch as normal. But if my fridge currently has a fermentation underway when I go to do this it will likely raise the temperature of the currently fermenting beer while the second beer cools to pitching temps. Assuming both beer are equal volume this temp swing could be half the difference of the two.

So when people are fermenting multiple beers in the one fridge how do they deal with this? Brew two beers close together and then wait until both are at picthing temps before pitching any yeast?

Benniee

I always start both fermentors together, and ensure both have yeast that likes the same temperature range. Then when you crash chill both are ready at the same time. But I also no-chill so it makes it easy to have a couple of brew ready to go at any stage.

QldKev

 

[argon]

I do this all the time... Albeit haven't done it with lagers at lager temps. As long as my tempmate probe is connected to the first fermenter, when adding the second one, the fridge will compensate for any temp changes.

I'd assume that putting an ambient temp fermenter in a 10c will have a minor affect on ferment 1. But probably not much to worry about. As an example I would never put a freshly made nc cube in the same fridge next to an active ferment, as I think the high temp differentials would have a larger effect.

In short, if you are directly monitoring the temp of ferment 1 and don't put wort next to it that's way too hot, I don't think it's much of a concern.

 

[QldKev]

But if you start the beers at different stages, I assume you don't crash chill?

When I brew, say using a US-05, currently I brew at:
Pitch yeast into room temp wort - this is because I no-chill the wort will be at room temp, and then I often pitch onto a used yeast cake, so I cannot tie up my fridge getting the wort to the best pitching temp.
Day 1 - 17c - to help get the temps down quick. my fridge does seem to be able to drop fermentors fairly quick. also I often pitch onto the prior yeast cake, so a slightly cooler temp helps it start of not too fast.
Day 2 - 18c - set to normal ferment temp - this may get delayed to day 3 or 4 if the beer is fermenting fast
Day 8 - 22c - beer should mostly be fermented out, this just helps it finish.
Day 10 - 4c - crash chill
Day 14 - transfer to keg, and back to step 1 refill fermentors


In the perfect world I would like a 3 week cycle; but I don't have extra fermenting space as my other fermenting fridge always has other drinks in it.

QldKev

 

[argon]

Qldkev at me or OP? Anyhoo I do crash chill, but I have a few options.
1. CC it in the same ferment fridge, by just dropping the tempmate
2. Move the whole fermenter to the keg fridge (have 4 kegs in 6 keg capacity fridge NEED MOR KEGS AND TAPS)
3. Rack into keg, CC in keg (before transferring to serving keg after however long)

These options allow me a fair bit of flexibility.

 

[reVoxAHB]

But in thinking about it I've come across a problem I'm wondering how others deal with. Lets say I am currently fermenting a lager in my fridge at around 10 degre, and I want to get another beer underway. Going through my regular brew day I end up with beer in the fermenter at around 25 degrees. What I would typically do is put the fermenter in my fridge to chill it to pitching temps, then pitch as normal. But if my fridge currently has a fermentation underway when I go to do this it will likely raise the temperature of the currently fermenting beer while the second beer cools to pitching temps. Assuming both beer are equal volume this temp swing could be half the difference of the two.

So when people are fermenting multiple beers in the one fridge how do they deal with this? Brew two beers close together and then wait until both are at picthing temps before pitching any yeast?

Benniee

I can't see having a second fermenter at 25C swinging the 10C all that much. I would just give it a go and take temp readings on both ferms every hour or so until you reach desired pitching temp on #2. The data will tell you what's happening for future or tweaking process. If you are doing ale, you're only talking 7 degrees (25C to 18C).. my ferm fridge would drop that in only a couple of hours. The ambient temp of the fridge wouldn't move too much (I'm guessing) esp as the probe will pickup a change and kick on the cooling, which will presumably run full guns until you hit target of 18C.

Now, to answer your question in how I deal with it.. simple: I ferment lagers with lagers and ale with ale. I always overpitch lagers+blowoff which has allowed me to skip diacetyl rest w/o issue. I have the facility to ferm 3x23L carboys / 1 lowest point of fridge, 2 highest. If I were attempting what you suggest, I would chuck the lager at bottom and (cooling) ale on top as I've noticed the lowest point of my fridge most stable/coolest (heat rises, and my fridge cooling plate is on upper shelf which would be closer to the wort to cool).

Hope helps
reVox

 

[Benniee]

Thanks for all the replies guys - some reports from those of you doing just what I am hoping to do.

Just to clarify I am considering either lagers with lagers or ales with ales - not trying to mix an ale and lager ferment. I think the problem with ales would be minimal due to my ambient temps being fairly close to ale fermenting temps. It's mostly the thought of dropping a mid 20's degree fermenter into the fridge with a 10 degree lager ferment underway.

In the past I have opted to crash chill the beer at the end of fermentation - which I obviously wouldn't be able to do here unless the two beers were due to finish fermentation at around the same time, which would typically mean a similar start time, which is not what I'm looking at here.

When the time is available I think I'll follow Revox's advice and do a bit of an experiment - and measure the temp of both fermenters during that initial stage when the second one is added into the fridge. From casual observation of my most recent ambient-to-pitch chill cycle it took the fridge around 6 hours to get the wort from 26 degrees down to 10. That is using a probe straped to the outer surface of the fermenter, under a little bit of foam insulation.

I'll report back with any results I get.

Benniee

 

[QldKev]

Qldkev at me or OP? Anyhoo I do crash chill, but I have a few options.
1. CC it in the same ferment fridge, by just dropping the tempmate
2. Move the whole fermenter to the keg fridge (have 4 kegs in 6 keg capacity fridge NEED MOR KEGS AND TAPS)
3. Rack into keg, CC in keg (before transferring to serving keg after however long)

These options allow me a fair bit of flexibility.

The post was open for anyone.

The main thing I was leading to is if you have a fermentor ready to crash chill and a second ready to pitch your yeast; due to being 1 week apart, then you can't ferment and crach chill in the same fridge. If you have the option of using another fridge for crash chill thats ok. For me I keep them fermenting at the same stage so I can use one fridge for fermenting and crash chill. It does limit me to only have an ale run or a lager run thou.

QldKev

 

[reVoxAHB]

Like everything in this hobby you could upgrade, too. That is to say, if you have the space etc., to introduce a second ferm fridge. Are you dispensing? I use my kegging fridge to CC when other ferms are still on.

I've given a couple of fridges away over the years, and see them pop up on freecycle fairly often. Throw on another $45 controller and problem solved.

But I do think if you give the experiment a run, you'll be fine. I'll be interested to catch your result.

Cheers

 

[Bribie G]

Do you have a temp mate or fridgemate? Then as an experiment you might want to place the probe somewhere in the cabinet where it measures the actual ambient temp in the fridge near where the colder lager is sitting. If the air is holding at 10 degrees then there's no reason why the cold lager should warm up. Another thought is that, if you have space, separate the two fermenters with a sheet of that sytrofoam with aluminium coating on each side, to prevent direct radiant heat from the warm fermenter affecting the cold fermenter (Damn -- Ross sent me a couple of panels as packing in a carton I received last week - I thought "wow I bet that could come in handy but I'm moving house in 2 weeks so I'll have to chuck it sadly") Bugger I could have sent you a sheet. No idea where you would get it, Ross (Craftbrewer) would know.

 

[felten]

I remember on the brewstrong episode on fermtemp, if you're controlling 2 fermenters at the same temperature, in the same fridge; they suggested to place the probe so it was touching both fermenters, inbetween them and insulating it from the ambient somehow.

 

[Benniee]

Well I finally got around to doing some testing over the weekend and thought I'd post back here with what I found.

My fermentation fridge was running at 10 degrees with about 22L of fermenting beer inside. Everything was nice and stable as that beer had been fermenting for around a week.

Second fermenter was added - it's temperature around 23-24 degrees. I have a small computer fan that circulates air around the fridge. The temperature probe for the thermostat was attached to the already chilled fermenter.

Well it was pretty much as Argon described earlier in this thread. The temperature of the first fermenter didn't really lift at all - the fridge just cycled a little faster than usual until the second fermenter was down near 10 degrees.

A good result for what I wanted to do.

So I guess you could conclude that as long as you have enough thermal transfer capacity in your fridge/freezer/fermentation chilling device you can add a fermenter to the chamber without greatly altering any fermentations that are underway.

Obviously the larger the temperature difference between the two the harder this becomes, but I have no intention of adding a NC cube next to my 10 degree ferment. It was more a way of getting from ambient to pitching temps.

Thanks again for the replies I got.

Benniee