Fermenting under pressure & tempature control

[Nate R]

Hello all. Still kinda new here so forgive me if starting a new thread was incorrect. I can't seem to find many threads on fermenting under pressure.

I just picked up a cornical conical fermenter. By using a spunding valve i can ferment up to 35psi safely.

However, my temp has been too warm. The basement maintains about 72° but i did not factor the increase during ferment. (I have read plus 5 degress)

So i want to ferment in a fridge. I am using an inkbird controller. Since there is no thermowell in the cornical, any suggestions for a temp setting? I can put the probe in a glass of water but should i adjust for the temp during pressure ferment? Say set it at 62°? Thoughts?

Also- anyone have any tips for fermenting under pressure? What is a good psi to set the relief valve for? Does temp control need to adjust under pressure?

Thanks all!!

 

[Sadu]

Hi Nate,

To answer your main question, I recommend taping the probe to the side of the fermentor with some insulation on the outside. Ie the probe pressed hard up against the fermentor, below the beer level, and the insulation means the probe is more exposed to the beer temperature than the fridge temperature. This system works very well for a lot of people, you don't need to go to the trouble or expense of thermowells.

A couple of general tips for pressure fermenting.
- You generally want to start at a low pressure (under 5psi) and let it build up over the course of fermentation. I like to start at under 5, and finish at 15-20.
- Don't pressure ferment any yeast-forward styles like hefeweizens or Belgian ales. It mutes the yeast character and they taste aweful IME.
- You can get away with fermenting a bit warmer under pressure. The pressure suppresses some of the esters that might form so you get cleaner beer at warmer temps. I'd say you can safely ferment 2-4c / 4-8f warmer than normal with no ill effects. This ferments the brew a bit faster but you can also just ferment at normal temperatures which is what I do.
- Use the free CO2 generated to purge your keg. Then do a closed-loop transfer into the keg and you get way less oxygen exposure. Especially great for anything hop-forward or any beer really.

 

[Nate R]

This is very helpful! Thank you!!

 

[khall12]

Hi Nate,

To answer your main question, I recommend taping the probe to the side of the fermentor with some insulation on the outside. Ie the probe pressed hard up against the fermentor, below the beer level, and the insulation means the probe is more exposed to the beer temperature than the fridge temperature. This system works very well for a lot of people, you don't need to go to the trouble or expense of thermowells.

A couple of general tips for pressure fermenting.
- You generally want to start at a low pressure (under 5psi) and let it build up over the course of fermentation. I like to start at under 5, and finish at 15-20.
- Don't pressure ferment any yeast-forward styles like hefeweizens or Belgian ales. It mutes the yeast character and they taste aweful IME.
- You can get away with fermenting a bit warmer under pressure. The pressure suppresses some of the esters that might form so you get cleaner beer at warmer temps. I'd say you can safely ferment 2-4c / 4-8f warmer than normal with no ill effects. This ferments the brew a bit faster but you can also just ferment at normal temperatures which is what I do.
- Use the free CO2 generated to purge your keg. Then do a closed-loop transfer into the keg and you get way less oxygen exposure. Especially great for anything hop-forward or any beer really.

When you say use the CO2 generated to purge the keg, are you saying basically transfer the CO2 in the headspace of the fermenter into the keg?

 

[Sadu]

When you say use the CO2 generated to purge the keg, are you saying basically transfer the CO2 in the headspace of the fermenter into the keg?

What I mean is that you route all fermentation gas through an empty keg to purge it.

You connect the gas out on your fermentor to the liquid port on the empty keg. Connect your spunding valve or airlock to the gas port on the empty keg.

Leave these connected while the brew ferments. All the CO2 produced by the brew, which is a lot, will push oxygen out of the keg.

You should actually wait 24h after fermentation starts before connecting this up, since the fermentor will need to purge or use the oxygen in the headspace. But after that, it's free CO2. This works for any fermentor, not just pressure fermentors.

 

[JSBULL]

What I mean is that you route all fermentation gas through an empty keg to purge it.

You connect the gas out on your fermentor to the liquid port on the empty keg. Connect your spunding valve or airlock to the gas port on the empty keg.

Leave these connected while the brew ferments. All the CO2 produced by the brew, which is a lot, will push oxygen out of the keg.

You should actually wait 24h after fermentation starts before connecting this up, since the fermentor will need to purge or use the oxygen in the headspace. But after that, it's free CO2. This works for any fermentor, not just pressure fermentors.

This is a pretty clever suggestion. You could just sanitize and lock up your keg in advance. You'd never need to re-open it if you're doing a closed pressure transfer. What fittings I'll need is already racing in my head.

 

[divrack]

Daahh! Now I've git that queen song stuck in my head...
Good advice though. I heard that hardly any commercial breweries actually ferment under pressure though I guess the bulk of their fermentation would be pressurised by our standards...

 

[Nate R]

Yes i have heard that too- commercial breweries don't ferment under pressure. But then o read that the sheer volumn and size of the fermentors alone creats pressure. Plus don't a lot use brite tanks? And/or carb stones?