Fermizilla - Pressure Fermentation - Noisy Ferment!

[Roadrunner]

Hi All

I've got a Helles fermenting in a Fermzilla 30L pressure fermenter. It's the first time I've tried this method and things appear to be going fine. However, when I open the fridge to take a peek there are all sorts of squeaks and whistles coming from the fermenter. I'm pretty sure the chamber is sealed as the spunding valve is showing the pressure at a constant (and when I close the valve the pressure increases) so not sure what is making these sounds? If it was air escaping from the chamber I'd assume the pressure would be lost as well but that doesn't seem to be the case. Is this normal? As I said, this is the first time fermenting under pressure so it could well be this is what to expect but I assumed the whole thing would be relatively silent.

 

[Dr_Jeff]

What do you have the pressure set to?

 

[Roadrunner]

Hi. This has been quite a learning experience for me so glad to have just about come to the end of my first pressure ferment! Pressure on spunding valve was 1 bar (15 psi) but it appears I made some incorrect assumptions on how it all works. I was convinced I had a leak as the spunding valve would show no pressure after a while but when I contacted the Malt Miller (where I bought the fermzilla) they advised that once primary fermentation is completed the CO2 in the chamber is absorbed into the beer and the pressure naturally drops (on the basis the yeast is no longer producing enough to maintain pressure). That kind of makes sense but I have my doubts. I'm going to get this brew into the keg at the weekend and get another brew on asap so will make sure I have everything setup properly and see what happens to the pressure. Certainly when I touched the disconnect valve attached to the spunding valve and gave it a gentle push a rush of air would come out so in my opinion something isn't that well sealed. I've now bought some brewers grease which should help with the disconnect/carbonation cap seal. I think I was a little naive and assumed the spunding valve would hold at 1 bar from the moment the fermentation started to the moment I cold crashed and kegged but I guess that isn't the case.

 

[iceman_ii]

Not done it yet, but I too picked up a firmzilla, but I am doing a 0 PSI ferment first...

I thought that you kept pressure on the vessel with a CO2 source at something below the spunding release pressure, so it never gets to atmospheric, even when the CO2 is absorbed back into solution. Say use a charge pressure of 25 if your spunding is set to 30... or am I missing the point here? Granted, I still need to do more research (its an engineer thing), but I thought this was the process, but I could very well be wrong.

 

[gello22]

This is from my last batch the orange line is pressure, the dark blue/purple is the beer temp, the red is gravity.
The pressure drops with cold crash then continues to drop because the c02 is more soluble at the lower pressure. The blips up in pressure is me adding C02 then it drops as it absorbs and I add more. I didn't do anything to seal leaks and you can see after a while is stabilizes. You can also see how the gravity changes with temperature. I checked and the changes line up really well with the predicted gravity vs temp.

You can see fermentation stopped on July 19th with a stable gravity reading.

The noise you are hearing is the spunding valve reliving the C02 from fermentation to limit the pressure. Do a kviek high temp ferment and it will sound like someone knifed your tires. You can see in the beginning the active fermentation was driving my pressure high with excess flow through the valve the drop down around the 15th was me readjusting the spunding

 

[Genuine]

I'll be doing my first pressure ferment this weekend on an Oktoberfest with my FZAR - I can't wait to see how it comes out. I see there are some people that are adjusting the spunding valve a day or so into fermentation and then I see people adding 10-12psi of co2 and setting the spunding pressure for the rest of fermentation....does it matter which way?

 

[gello22]

Definitely set it ahead of time or you could be surprised. Sometimes I need to adjust because there is a big difference between cracking pressure at low flow and high flow aggressive fermentation.

 

[Genuine]

I ended up pressurizing mine to 12 psi, set up spunding valve which confirmed the pressure. It's currently fermenting away happily and I hear a slight hiss if I put my ear up the to valve.