Cold crashing using CO2 to avoid oxygen back? Fermzilla style fermenter.

[Panderson1]

I have a new fermizilla with pressure kit and blowtie spunding valve/regulator.

Is there an easy way to cold crash? I'm not finding many results on YouTube or forums.

 

[Elric]

If you pressure fermented there should be sufficient pressure in the fermenter to be able to just drop it straight into the fridge/freezer for the cold crash.

 

[JimC]

^^ This. You only need a few PSI to cold crash with a spunding valve on and not pull negative pressure.

 

[Panderson1]

^^ This. You only need a few PSI to cold crash with a spunding valve on and not pull negative pressure.

So put the spund valve on and set to 3psi (never used it before). Do I leave gas hooked up to the gas line on the fermenter? Or set it at 3psi then unhook it. Sorry this is all new to me.

 

[SmallScaleOperator]

Not really knowing anything about the liquid and headspace volume, or the strength of your fermenter, I would recommend more than 3 psi. If your fermenter is rated for 10 psi that would be a safer bet to prevent a vacuum that could potentially damage your equipment.
If you are currently at normal atmospheric pressure and fermentation is complete, just pressurize your fermenter and cold crash. For your next brew you would attach the spunding valve during fermentation and set it to your desired pressure. pressure will build up as your yeast produce CO2, so when your ready to cold crash you already have pressure built up in there.

 

[Panderson1]

Thanks. Yeah I have a 12 gal firmzilla so a lot of head space. I added some CO2 and set the psi on the spund to 5. Overnight the natural Co2 raised it to 8. I think I'll leave it there for now. This is all so weird to me as I'm old school. Took a 3 year break and now so mu h talk about pressure in the damn fermenters!

 

[DuncB]

I don't normally bother to add any CO2 when I start fermentation. The yeast needs a bit of oxygen to get started and once the ferment is underway loads of CO2 is made which will push out any unused O2 via the spunding valve. Depending on what you are brewing some leave the PRV open for first 24 - 48 hours to allow esters etc. If you are trying to suppress these then leave PRV shut and set your spunding valve to whatever you choose. A few psi is a good safe starting level, I tend to tighten the spunding valve up once Krausen has fallen to build more pressure so less force carbonation needed later. Currently a Zwiec Lager clone at 25 psi day 4 with kviek and a stout at 19 psi which will later go on nitro.
As far as cold crash you won't need to add more CO2 if you have 15 psi when you start. Dr Hans brewery has a good calculator for pressure fermenting and final carbonation that can get you in the ball park.
Would recommend David Heath homebrew on youtube for some good pressure ferment advice and pushing the boundaries Dr Hans as well.
Learn about the trub removal procedure and watch this on the videos otherwise it can get messy!!
Also good advice about closed transfer on short circuit brewing.

Of course loads of advice on this forum and there are more ways to skin a cat than there are cats ( maybe).