No problem, let me keep explaining
My Keezer is at 38-40F right now. I want 2.5 vols in my beer. That's 11PSI. I have 5 ft lines right now. Will 11PSI be appropriate to both CARB and SERVE my beers for the time being? Or do I need to adjust the serving pressure? (According to the website/calculators I have looked at, 11PSI seems to be the "answer" given for my setup)
Yes to the first question, no to the second. Do not change the serving pressure, this will cause foaming and eventually change the carbonation level. The most consistent way to carb and serve beer is to keep your serving pressure and carbonation pressure the same. There are some "burst carbing" shortcuts that can speed things up, but they're risky and if you're new to the game you should keep it simple. Set the beer at 11 psi, after 2 weeks or so there will be 2.5 volumes of CO2 dissolved in the beer. You've got it right. Line length has nothing to do with carbonation level of the beer in the keg, so at this point your 5' lines are irrelevant.
Also, thanks for the info Zach, but it doesn't quite answer my question as to why 10ft is so much better. 10ft provides more resistance, so you need more PSI to push the beer through it. So using longer lines with the same PSI means it will flow slower, right? Isn't a "too low" pressure one cause of foaming also?
A major cause of foam is that the beer is exiting the faucet too quickly; this rapid change in pressure causes CO2 to break out of solution and you have a glass full of foam. To slow down the beer, you need more resistance, so you want longer lines. You are correct: you don't need more PSI to push the beer through 10 feet of tubing, it will just come out slower at a given PSI. And this is exactly what you want. Too low of a pressure will not cause foaming, it will just make you wait another second or two for your beer. And it buys you a lot more freedom: what if you want your next batch at 2.7 volumes of CO2? Or try serving a little warmer? Having lines that are nice and long means you can serve a variety of styles without worrying. If the slightly slower flow rate is really a problem, you can trim a little bit off until you get it where you want.
As your lines get longer you do have to make sure that the entire length (and the faucet) are nice and cold. This is why a fan can help tremendously.
There is no fixed "PSI per foot" number: that number is based on the friction as beer flows through the tubing, and it's very highly dependent on the flow rate of beer through the tubing (usually to the 2nd power!), the temperature, the density, and the viscosity. For very cold beer flowing very quickly through the line, the PSI/foot number will be higher than for your system.
I like to compare it to wind/air resistance on your car: the faster you drive on the highway, the more resistance you see from the air. This is why you get better gas mileage at 65 mph compared to 85 mph. Additionally, when it's cold out and the air is very dense, the wind resistance is going to be even higher. Do you get what I'm saying?
If I drive my Honda Civic on the highway at 65 MPH on a warm day, maybe I'll need 10 horsepower to counter the wind resistance (just making up number here). But you could drive your Ford F350 on the same highway at 85 MPH on a cold day, and need 50 horsepower to counter the wind resistance.
Just like you can't make a generalization like "this highway requires 10 horsepower to counter the friction as you drive along it," you also can't say "this tubing requires 2 PSI/foot to counter the friction as beer flows through it."
The bottom line is that the "psi per foot" that the calculators give you is irrelevant for your situation. It's based on a commercial setup that requires a high flow rate out of the faucet, since they want to be able to sell XX beers per hour to stay in business. To serve foam-free at that high flow rate, they need to keep the beer very cold. Since us homebrewers like our beer a bit warmer, and sometimes we like to play around with carb levels, longer lines are the way to go.
There are people on this forum that have success with 5' lines. But the vast majority of us use 10-12 feet of standard 3/16" ID lines, and have found that this leads to foam-free pours.
), but I'd suggest that you consider longer lines. I started with the 5ft lines in the package setup I bought (I have about a 1ft rise) and wasn't having big foam problems, but it was hard to dial it in for the level of consistency I was after.
