I have been doing pressure fermentations for a brief minute, only with lagers, because that’s all I normally brew. I pressure ferment them at normal lager temps. I’m not looking to speed things up. I am brewing a BGSA this weekend. Pitching @67 and will let it rise to mid 70’s.
Is there any benefit or drawbacks to pressure fermenting an ale or a high gravity ale at elevated temps? Again, I don’t have much experience pressure fermenting and I don’t understand it completely.
The benefits are purging the receiving keg and closed xfers, which is definitely better. Every yeast reacts different to pressure, some ale yeasts produce esters under pressure no matter what. Until I learn how an ale yeast performs under pressure on my gear, I let pressure build natively to 3-5 psi and raise the pressure in the second half of the ferment and xfer fully carbonated beer into the keg. In split batches with a new ale yeast, I typically let the one batch build to 10 psi, for most ale yeasts there is virtually no difference in the glass. I don’t think there are any drawbacks.
I generally set my PRV (attached to the gas-in of a 5 gallon keg)to 2-3 PSI during the early part of fermentation on ales. Once fermentation starts slowing down (i.e., I don’t hear a hiss from the PRV any more), I pull the PRV off the keg and let it build up carbonation. It’s not usually fully carbed when I’m done, but it’s generally halfway there.
I have noticed less ester production than expected from some ale strains, but I’m not convinced it’s from the small amount of pressure. I brew smaller (3 gallon) batches, and I suspect my pitch rate is a more likely culprit.
Your question about ales under pressure is a good one. They can ferment super clean due to suppressed esters and faster at the warmer temps, but I would put some pressure on the fermenter at the onset, because the two aspects counter each other somewhat - the warmer temp will encourage ester formation in the early part of the fermentation, while the pressure will suppress ester formation. I think it is very much yeast strain dependent and some balancing through experimentation would be good to do, perhaps splitting batches to compare. Either way, warm temps at no pressure is asking for potential issues…but then again there is always Kviek yeast if you want warm and quick - but you said time wasn’t an issue.
Cheers!
La fermentación a presión y las mangas termoencogibles están relacionadas en el sentido de que ambas técnicas se utilizan en la producción de bebidas carbonatadas, como la cerveza y los refrescos.
Thanks for that answer! I did not take into consideration of starting fermentation with pressure added. Totally an arbitrary number here but I am thinking starting at 5psi and then 10psi after ferm temp reaches 74-75.
Thoughts
That sounds reasonable for ales. I go to as high as 15 psi on lagers (cold temps too - I don’t find the need to go warm with lagers, though I have done it; my lagers finish in under a week with no problem at regular cold ferment temps).
Are there advantages to pressure fermenting lagers at cold temps? Is it simply to have carbonated lager beer at the end or something else?
Cleaner outcome and it seems to speed things up over regular cold fermentation. But having carbed beer is a slight plus. Just my anecdotal findings - others may differ.
Some people do it to mimic the conditions of commercial brewing where the yeast is under hydrostatic pressure due to the large volumes. For best results, my understanding is that you want to pressurize the fermentor as soon you pitch the yeast.
Thanks for the replies. Aren’t some commercial lager fermentations done in non-cylindroconical tanks with less pressure?
very, very few
Well, Pilsner Urquell uses open fermenters. You can’t get less pressure than that 
I also heard a recent interview with Vinnie from Russian River where he said that they are brewing some of their beers (inclusing STS Pils) in open fermenters as well.
I don’t think Urquell open ferments much anymore. Small amounts in the old wooden tanks in the cellars but majority of production beer is done in unitanks.
There are many smaller and mid sized German breweries that do open fermentation. If you look at maps of breweries in Germany with a satellite view the big ones have CCV tank farms visible
The yeast is under pressure due to the large volume of liquid on top of it.