Cold Crashing

[Redlantern]

Don't be so sure. I've used a 4ft piece of 1" ID tubing for my blow off and it sucked back a good pint or two of sanitizer into my carboy once when I forgot to remove it and cap the carboy.

Depends on the volume. I do not even have two pints in my blow off. No reason to have a ton of actual liquid. or at least no reason to have the tube all the way to the bottom. If it is only an inch deep in a mason jar then none will get sucked up

 

[trav77]

So then you dont worry about it getting sucked back in.

I also am going to use a freezer witha an inkbird at about 32f

Yup. I'm not really on this super paranoid about oxidation train. Not saying it's not an issue but i only keep 2 kegs on tap at a time so they turn over pretty quick. No noticeable issues.

 

[trav77]

Also if you are using a thermowell make sure you have a 2 stage controller with a heat source (I use a brew belt). Otherwise your freezer can overshoot and freeze your beer. If your controller temp probe is measuring ambient then less of an issue.

 

[btbnl]

Time for some math:

Assuming that you're cold-crashing from around 70F to just above freezing, the volume of the gas in the head-space will shrink by about 7%, and of the beer by about 0.2%.

As a specific example, a 6G fermentor with 5G of beer will suck back ([6-5] x 0.07 + 5 x 0.002) = 0.08G, or about 2/3 pint.

So if you wanted to use your blow-off solution as a reservoir without sucking any liquid all the way back into the fermentor, you'd need at least 8 feet of 1/2" diameter tubing.

FWIW I've put together a little spreadsheet here to calculate the total suck-back volume and the corresponding line-length for user-specified fermentor and beer volumes and blow-off tube diameter.

 

[MagicMatt]

Time for some math:

Assuming that you're cold-crashing from around 70F to just above freezing, the volume of the gas in the head-space will shrink by about 7%, and of the beer by about 0.2%.

As a specific example, a 6G fermentor with 5G of beer will suck back ([6-5] x 0.07 + 5 x 0.002) = 0.08G, or about 2/3 pint.

So if you wanted to use your blow-off solution as a reservoir without sucking any liquid all the way back into the fermentor, you'd need at least 8 feet of 1/2" diameter tubing.

FWIW I've put together a little spreadsheet here to calculate the total suck-back volume and the corresponding line-length for user-specified fermentor and beer volumes and blow-off tube diameter.

I don't have time to check the actual math here (it's pretty simple but I'm about to leave), but plugging my numbers into your calculator does not agree with my experience. As stated previously, I use 1" ID hose and have had over a pint get sucked back. 6.5 gallon carboy, 5.5 gallon batch, 70°F to 32°F. Your calculator says I would only need 2.03 ft of hose to prevent suckback, but mine is 3ft and it happened.

 

[doug293cz]

I don't have time to check the actual math here (it's pretty simple but I'm about to leave), but plugging my numbers into your calculator does not agree with my experience. As stated previously, I use 1" ID hose and have had over a pint get sucked back. 6.5 gallon carboy, 5.5 gallon batch, 70°F to 32°F. Your calculator says I would only need 2.03 ft of hose to prevent suckback, but mine is 3ft and it happened.

"Volume" drop due to temp change from 68˚F to 32˚F is indeed 7.3% (293.15 / 273.15 = 1.07322.) However, the temp induced "volume" drop is not the whole story. Prior to cold crashing, the partial pressure of CO2 in the headspace is 14.7 psi. Cooling increases the solubility of CO2 in the beer, and if allowed to come to equilibrium, the CO2 partial pressure would drop to ~8.7 psi. The loss of 6 psi pressure in the headspace needs to be made up by air suck back. So for 1 gal headspace, you need to suck back 6 / 14.7 = ~ 0.41 gal of air. How much you actually suck back will depend on how long you cold crash.

Brew on

 

[btbnl]

"Volume" drop due to temp change from 68˚F to 32˚F is indeed 7.3% (293.15 / 273.15 = 1.07322.) However, the temp induced "volume" drop is not the whole story. Prior to cold crashing, the partial pressure of CO2 in the headspace is 14.7 psi. Cooling increases the solubility of CO2 in the beer, and if allowed to come to equilibrium, the CO2 partial pressure would drop to ~8.7 psi. The loss of 6 psi pressure in the headspace needs to be made up by air suck back. So for 1 gal headspace, you need to suck back 6 / 14.7 = ~ 0.41 gal of air. How much you actually suck back will depend on how long you cold crash.

Brew on

Good point! I've updated the calculator also to include the absorption, which is almost always the dominant effect if the system is left to reach equilibrium. In MagicMatt's case he'd need about 12 feet of 1" line, and 3 feet of line would allow up to 3 pints of suck back!

 

[MagicMatt]

Wow.

You know, for a second there I almost starting contemplating how to get 12ft of hose in there. Lol, yeah, not going to happen. I actually rarely even need blow offs any more with keen temp control, and now I always put a solid bung in when cold crashing.

Actually, funny I say that because I just put a blow off on a carboy from this weekend, but only because it was a 5.75 gallon batch and didn't realize until I was done boiling that I only had empty 5 and 6 gallon carboys left. So I only had a couple of inches of headspace in the 6g. It got close, but looks like I may not have needed it anyway.

 

[day_trippr]

Yes there is. It just bubbles in both directions so it doesn't suck the liquid back. It'll suck plenty of air in though.

Duh. Of course.
But that isn't what "suck-back" has always been taken to mean.

fwiw, here's how I cold-crash...



Cheers!

 

[bleme]

I think most of us cold crash in a freezer, not a fridge. A freezer can get a heck of a lot colder than ice water or a fridge. Water is definitely a better conductor than air, so by that measure ice water will chill faster than a fridge/freezer at 32°F, but I'm not sure that ice water will chill faster than a freezer set on 0°F.

I use fridge/freezer interchangeably because both are run through my temp controllers. I haven't tried cold crashing with my freezer set at 0F because I don't want to freeze my beer. I have done it with wort before, when I forgot to bring ice home though. It took almost 2 hours to get to pitching temp, while ice water will get it there in 15 minutes.

 

[trav77]

Duh. Of course.
fwiw, here's how I cold-crash...
View attachment 380378

OK maybe a dumb question but is the balloon necessary? I've seen similar setups a number of times now that include it. If you just set your CO2 regulator to very low pressure (1 psi?) would that not be adequate? Or is the balloon necessary to keep the stopper from popping out even at low pressure? Also is it just a regular party balloon? Any off flavours from that itself?

 

[btbnl]

fwiw, here's how I cold-crash...

What's the hardware there between the bung and the gas-in post for the quick disconnect?

 

[Redlantern]

I see the balloons and the thought crosses my mind - "Hey - helium filled balloons!!! and carbonation!!!"

Boy, talk about getting light headed.....

buh-dum bump
(groan) Thank you - I 'll be here all night!


I apologize to anyone that read that......

 

[MagicMatt]

I've been actually looking into these vacuum relief valves: http://a.co/0YoS3rD

Think of it as a reverse spunding valve. Instead of releasing positive pressure when it gets too high, it releases the vacuum when the pressure gets too low. Haven't pulled the trigger yet (not like it's expensive, just haven't had the time to figure out what hardware is needed to hook this to a gas QD).

 

[seabrew8]

Duh. Of course.
But that isn't what "suck-back" has always been taken to mean.

fwiw, here's how I cold-crash...

View attachment 380378

Cheers!

Wow, i'm a KISS guy but thats pretty neat man!

 

[btbnl]

After visiting various hardware stores to try to figure out how to connect a gas-side quick disconnect to a bung, I suddenly realized I that all my Speidels come with tap fittings!

Close the tap, connect a balloon full of CO2, swap the whole thing in for the airlock, open the tap, and we're all set to cold-crash.

And 12 hours later when the temperature had dropped and the balloons had been sucked empty, simply close the tap, remove, replenish and restore the balloon, and re-open the tap. And with the vent-hold in the top of the tap I can even purge the tiny amount of air that gets in when the balloon is removed before re-opening.

So simple.

 

[StephanHaus]

Cold Crashing helps to flocculate all of the floating yeasts. When they flocculate, the added mass increases the likelihood of them falling down to the bottom of the carboy, thus clearing beer. If you combine cold crashing with gelatin finings, you'll likely have a crystal clear brew!

 

[Bus06]

I'm a little confused about the gelatin thing. Are you all talking about the powder gelatin that you can get at walmart or is there something different for brewing? I know... Might be a stupid question. But I had to ask.

 

[brewbama]

I'm a little confused about the gelatin thing. Are you all talking about the powder gelatin that you can get at walmart or is there something different for brewing? I know... Might be a stupid question. But I had to ask.

Not stupid. Just plain Knox Gelatin. http://www.bertusbrewery.com/2012/06/how-to-clear-your-beer-with-gelatin.html

 

[tgmartin000]

Hey day tripper, do you have a parts list for your setup? I want to build what you're doing, but can't figure it all out. Thanks!

 

[trav77]

I tried out the 2 jug blowoff method on my latest brew:

View attachment ImageUploadedByHome Brew1485908999.340621.jpg

Idea is that the active fermentation purges the first jug with CO2 and the second one acts as the airlock. Then when you cold crash starsan from jug 2 just gets sucked back into jug 1 and CO2 from jug 1 gets sucked back into the fermenter.

Worked pretty well I'd say. And it's simple in that you just leave the setup as-is throughout fermentation and cold crashing.

Quite a bit of starsan sucked back into jug 1 so that's about the amount of air being sucked into the fermenter without some way to mitigate. Whether or not that has a significant effect still up for debate...

View attachment ImageUploadedByHome Brew1485909260.525326.jpg

 

[Frostman]

I had the same experience with the same size hose. I didn't cold crash per se. I pitched at 68 F and by the time fermentation was complete I had a couple of pints of StarSan sucked back on top of my very first batch. My basement is 63 F. Apparently the 5 degree differential, fermentation completion and bad weather pulled half a blow off tube up where it then dribbled onto the beer for 10 days while I was on vacation. There's a photo in the beginner thread of the yellowish layer on top. Really jacked the final pH too. I racked the bottom half off and learned a very important lesson.

If at first you don't succeed..... brew, brew, brew again!

 

[cmac62]

I usually cold crash in my serving keg with the airlock closed and when completed just use the CO2 to pressurize for forced carbing. The first few pints may be a bit cloudy, but after that the beer is really clear, until it spits at me. Brew on

 

[LordRogan]

After visiting various hardware stores to try to figure out how to connect a gas-side quick disconnect to a bung, I suddenly realized I that all my Speidels come with tap fittings!

Close the tap, connect a balloon full of CO2, swap the whole thing in for the airlock, open the tap, and we're all set to cold-crash.

And 12 hours later when the temperature had dropped and the balloons had been sucked empty, simply close the tap, remove, replenish and restore the balloon, and re-open the tap. And with the vent-hold in the top of the tap I can even purge the tiny amount of air that gets in when the balloon is removed before re-opening.

So simple.

This sounds good. The picture you shared isn't openable. Could you be a legend and re share a photo of the set up? Cheers!

 

[MPBeer]

Brewing newbie here trying to figure out how to cold crash well... sorry for hijacking a post.

1. Will my yeast survive from cold crashing? Or should I put some new yeasts in my bottle to get carbonation.
2. Lots of guys here are talking about the liquid getting sucked back... is it a serious problem? I asked a guy at my brewing store and he told me that just live with it and add some starsan to my airlock.

 

[doug293cz]

Brewing newbie here trying to figure out how to cold crash well... sorry for hijacking a post.

1. Will my yeast survive from cold crashing? Or should I put some new yeasts in my bottle to get carbonation.
2. Lots of guys here are talking about the liquid getting sucked back... is it a serious problem? I asked a guy at my brewing store and he told me that just live with it and add some starsan to my airlock.

Yes your yeast will survive cold crashing just fine. No need to add more yeast at bottling.

With an airlock, either an "S" tube or 3-piece (properly filled), will not suck back more than a few drops of liquid. Liquid suck back becomes an issue when instead of an airlock, you use a blow off tube with the end placed in a reservoir of liquid.

Air will always be sucked back thru an airlock. Air will be sucked back thru a blow off tube if you suck back enough liquid to expose the end of the tube.

Brew on

 

[Louz]

I tried out the 2 jug blowoff method on my latest brew:

View attachment 387083

Idea is that the active fermentation purges the first jug with CO2 and the second one acts as the airlock. Then when you cold crash starsan from jug 2 just gets sucked back into jug 1 and CO2 from jug 1 gets sucked back into the fermenter.

Worked pretty well I'd say. And it's simple in that you just leave the setup as-is throughout fermentation and cold crashing.

Quite a bit of starsan sucked back into jug 1 so that's about the amount of air being sucked into the fermenter without some way to mitigate. Whether or not that has a significant effect still up for debate...

View attachment 387085

I like this a lot! Seems like a great solution. I'm gonna try this next time. Thanks

 

[angry_gopher]

I usually cold crash in my serving keg with the airlock closed and when completed just use the CO2 to pressurize for forced carbing. The first few pints may be a bit cloudy, but after that the beer is really clear, until it spits at me. Brew on

When you use the keg to cold crash do you use fining gelatin in the fermenter before racking?

ETA, Sorry, I found the answer on the main site. Apparently, fining is more efficient after crashing. FWIW - my wife has used fining for winemaking and I know that she never cold crashed that stuff.

 

[btbnl]

This sounds good. The picture you shared isn't openable. Could you be a legend and re share a photo of the set up? Cheers!

 

[cmac62]

When you use the keg to cold crash do you use fining gelatin in the fermenter before racking?

ETA, Sorry, I found the answer on the main site. Apparently, fining is more efficient after crashing. FWIW - my wife has used fining for winemaking and I know that she never cold crashed that stuff.

I don't fine (except for worflock in the boil). A little cloudiness doesn't bother me, and after the keg has been in the fridge for a while everything drops out and all my beers look like lagers.