Ferment Under Pressure in Keg batch size?

[RichBenn]

I'm thinking about getting a spunding valve and fermenting under pressure. I mostly do Pale Ales and IPAs (occasionally NEIPA). The plan would be using the fermentation in one keg, with a connection to a second keg to use as a serving keg and hook the spunding valve to the serving keg.

So the big question, is do I need to reduce the batch size to, like, 4.5 gallons? Also, having heard some comments about losing esters, will doing a NEIPA or west coast with a fruity yeast yield worse results than traditional methods?

Thanks in advance for any help. Been trying to get educated before I buy yet another tool.

 

[DuncB]

I'm thinking about getting a spunding valve and fermenting under pressure. I mostly do Pale Ales and IPAs (occasionally NEIPA). The plan would be using the fermentation in one keg, with a connection to a second keg to use as a serving keg and hook the spunding valve to the serving keg.

So the big question, is do I need to reduce the batch size to, like, 4.5 gallons? Also, having heard some comments about losing esters, will doing a NEIPA or west coast with a fruity yeast yield worse results than traditional methods?

Thanks in advance for any help. Been trying to get educated before I buy yet another tool.

There's a thread something like fermenting and serving same keg to find for help with this.
You do need smaller batch for sure.

https://www.homebrewtalk.com/threads/keg-fermenting.727083/post-10260034
https://www.homebrewtalk.com/threads/calling-on-those-who-ferment-and-serve-in-the-keg.726918/
https://www.homebrewtalk.com/threads/keg-fermentation-headspace.710891/

 

[RichBenn]

There's a thread something like fermenting and serving same keg to find for help with this.
You do need smaller batch for sure.

Seen those; not really clear how much headspace to try. Someone used 3.5 gallons; another worked fine with 5 gallons. It was an old thread, so I thought I’d start a more specific thread. I imagine the type of yeast, pressure, etc. may affect results.

 

[Broken Crow]

Are you planning to use a keg you already have? There's always 'oversized' kegs that could net you a full 5G serving keg;
https://www.morebeer.com/products/torpedo-ball-lock-keg-6-gal.htmlhttps://www.ontariobeerkegs.com/ob-keg-6.5gal.html(Sorry for the Canadian link... can't find this in the US, but someone likely carries it.)
Personally, I have an obsession with having my 5G kegs filled to an actual 5G of clear beer (My favourite ale always has that last inch or so in the fermenter that never fully clears...so by the time I get to there it goes in a baby-keg or bottle while the clearest from the top is in the 5G keg(s)) I've taken to doing 12.5 gallon batches in a sanke with my TC-Fermhead with floating diptube on top. The 7.9G sanke is perfect for a 5G batch.
Just sayin'

 

[odie]

I've been fermenting and serving int he same keg for a couple years now. I have no issues doing a full 5 gal batch in the keg.

For ales I use a blow off tube to promote esters and yeast expression for the first few days, then spund under pressure to around 25psi to carb up.

For lagers I spund immediately around 5-10psi, then 25psi to finish and carb up.

Only the Hefe is an issue. The blow off tube is gonna spit krausen out. It's just what Hefe does. Let is blow and then spund after a few days.

But I always get 5 gal wort into the keg to ferment and it comes out fine.

 

[Broken Crow]

I've been fermenting and serving int he same keg for a couple years now. I have no issues doing a full 5 gal batch in the keg.

For ales I use a blow off tube to promote esters and yeast expression for the first few days, then spund under pressure to around 25psi to carb up.

For lagers I spund immediately around 5-10psi, then 25psi to finish and carb up.

Only the Hefe is an issue. The blow off tube is gonna spit krausen out. It's just what Hefe does. Let is blow and then spund after a few days.

But I always get 5 gal wort into the keg to ferment and it comes out fine.

I suspect it's to do with the 'personality' of the specific brew; My usual favourite mild, when I first developed it in a 6G carboy would always blow so much krausen that after the trub, the most I ever got in the keg was almost 4.5G, whereas other recipes left with >5G. I've been biased to err on the side of caution and oversize my fermenters.

 

[apache_brew]

I think you've got the right idea. Blow off the initial fermentation and then cap or spund the later half to lock in aroma. I usually ferment 14~14.5 gallons in 1/2 bbl sankey kegs no problem as long as you does with ferm cap. For 5 gallon batches, the slim quarter bbl sankey's are the perfect size.

 

[Yesfan]

..............For lagers I spund immediately around 5-10psi, then 25psi to finish and carb up........

I've got a pilsner, pitched with Urkel, that's riding at 15psi now, 66F. How soon do you go to 25psi? This Saturday will be a full week for me. On another note, when do you do a D-rest? Is that different with pressurized fermentations? Sorry for the off topic, but it did seem relevant.


I did a 4 gallon batch so I'd have head space. The other reason is 4 gallons is about the max size for my stove and I've been loving my AC right now (my God has it been hot this week!).

 

[odie]

about a week is probably good to let it rise to 25psi and finish. At fermentation temps that will be in the ball park psi that will get you carbed to your target CO2 volume for most beer styles.

I use the red PRV that are around 25-30 psi so I just remove the spunding valve and let it do whatever until it's done fermenting.

Some study I read once.... supposedly the yeast will stop propagating after some pressure. I've seen articles that say that happens around 35psi or there abouts.

I figure that after about a week, the yeast pitch has had plenty to time to grow its colony.

too much pressure will kill yeast. But that level will also explode any fermentation vessel. Its like a few thousand psi to kill yeast.

I don't really do a D rest. I think with lagers under pressure you can ferment a bit warmer and that basically negates having to worry about a d rest.

Not really sure a D rest even applies to an ale.

 

[Yesfan]

about a week is probably good to let it rise to 25psi and finish. At fermentation temps that will be in the ball park psi that will get you carbed to your target CO2 volume for most beer styles.

I use the red PRV that are around 25-30 psi so I just remove the spunding valve and let it do whatever until it's done fermenting.

Some study I read once.... supposedly the yeast will stop propagating after some pressure. I've seen articles that say that happens around 35psi or there abouts.

I figure that after about a week, the yeast pitch has had plenty to time to grow its colony.

too much pressure will kill yeast. But that level will also explode any fermentation vessel. Its like a few thousand psi to kill yeast.

I don't really do a D rest. I think with lagers under pressure you can ferment a bit warmer and that basically negates having to worry about a d rest.

Not really sure a D rest even applies to an ale.

Thanks. I'm going to let it ride, then let it rise to 25psi, and hold that for the next week (again at 66F). Next weekend, I may put it in the kegerator and let it cold crash for 3 weeks before tapping.

 

[osakarocks]

I've been using a 6 gallon Torpedo keg for a few years now. It's the perfect size for my needs and I can also no-chill in it. I literally just pump nearly-boiling beer into it, then drop a stainless steel tube of flavor hops in after it cools to around 165, then the next day, I drop another tube if dry hops in along with a packet of yeast (I also oxygenate the wort first). Works great!