Fermenting Under Pressure on the Cheap and Saving the Planet!


By Evan Knezic
Spunding valve and keg jumper line
I originally started home brewing because honestly it was cheaper than buying good beer and I was broke. So, I figured out how to make or copy most things. Things have come a long way since then and I’m not broke now, but I still like to save a buck if I can and especially conserve where possible. So while watching a great video from Vito and Chris about fermenting under pressure my ears perked up when they said that there’s a CO2 shortage. I decided right then to do something about it with my next batch!

Oxygen free closed loop transfer homebrew!

Step #1

Fermenting in a Fermzilla, Cornical, or other pressurized conical fermenter is the best. However, if you want to accomplish something similar you can use any standard keg. You’ll need a spunding valve to safely control the pressure and you’ll still need to allow some headspace, at least ½ gallon or more. To get a good clean oxygen free transfer when it’s finished fermenting, you’ll want a floating dip tube. Now you could really be cheap and use a fishing bobber for 75 cents but you’ll have trouble sanitizing it.

Step #2

Now here’s a tip in truly economizing, rather than putting your spunding valve on the keg that you’re using as a primary fermenter you’ll want to bring in the keg that you’ll plan on serving in. You’ll need to make a jumper with a “gas in” and a “beverage out” ball lock fittings. Place the gas in fitting on the primary fermentation keg and the beverage out fitting on the secondary empty keg. Then install the spunding valve on the secondary keg. In this case I only fermented 2.5 gallons, so that’s why I’m using the slimline torpedo keg. Adjust the spunding valve, in this case a blowtie, to the pressure you want to ferment at. I’m using 10 psi. As the CO2 leaves the primary into the secondary and out through the spunding valve it'll fill the secondary with FREE CO2! Saving money and the planet all at the same time.
Closed keg transfer

Step #3

Once you’ve reached FG, disconnect the jumper. Switch out the “gas in” ball lock fitting for a second “beverage out” ball lock fitting.
Setting up a closed beer transfer

Step #4 

Now connect the jumper on both kegs. Connect a CO2 tank to the gas in side of the primary keg with the pressure set at the same PSI that you fermented at, in my case 10 PSI.
Oxygen free homebrew closed loop transfer

Step #5

Now slowly lower the PSI of the spunding valve by .5 – 1 PSI.
Spunding valve to regulate flow
As the pressure releases through the spunding valve, the beer will begin its oxygen free journey from your primary keg to the secondary. By using the floating dip tube you’re transferring the cleanest beer. Watch your jumper line for clarity and disconnect it before the yeast transfers from your primary into the secondary. Sometimes it’s fun to do things the old cheap hard way.

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