don't mean to resurrect a 4 year old thread, but I have just started digging into the balancing act/proper serving pressures/etc and didn't want to start a whole new thread.
Some of this is straight-forward (set and forget), but some is pretty confusing.
Why would you change line length? Then if you have different styles that call for different carb levels, wouldn't you need different sized lines for each? I can't picture having a "stout" line and a "berliner" line and an "IPA" line...
Really you could just use the longest line needed for maximum carb level you want to serve at - the beers carbed lower would pour a little slower but otherwise no big deal.
If you serve at a PSI different than that which is in the keg (impossible to know?) then wouldn't that throw off a pressure gradient?
So if you carbonate, say, a berliner at 25 PSI for a week, then wouldn't you have to also serve it at 25 PSI? If you changed the regulator down to 12 PSI, to accommodate a 10' line, wouldn't that throw off the pressure?
Would it be enough to cause excess foam or flat beer?
Yes, you'd get likely get foaming in that situation. Hence the idea that you shouldn't distinguish between equilibrium (carbing) pressure and serving pressure - they should the same, and you need to balance your system to accomodate that.
If you set it and forget it, say around 14 psi or so, how do you achieve varying levels of carb? Say one week I have a stout, one week I have a berliner? I need the stout around 2.0 vols, and the berliner way up around 3.4.
You'd need to set a different pressure for each keg (assuming they're all at the same temp) - see below
Our CO2 tank has multiple uses - purging, CO2 transferring, use with the bottling gun, and carbing. Would it be best to just get another tank/regulator for carbonation alone, or does it matter?
I feel like it'd be a royal PITA to have to disconnect a beer mid-carb to purge/xfer/bottle another beer, and then hook it back up to continue carbing.
If just purging and the exact pressure doesn't matter you can run an extra line off your regulator or manifold, then you don't need to disconnect kegs each time. If you want to carb and serve beers at different pressures simultaneously you don't need another tank but you will need more regulators - either dual primaries or some secondaries downstream for each pressure that you want to use. To me it's not that big a deal to carb exactly to style, and I'd rather not deal with changing pressures all the time, so I have 6 lines coming of my primary regulator that I keep at about 2.6 vols. I then have a secondary regulator downstream with a few lines coming off that I keep at 1.5 vols to carb beers going on the beer gas for the stout faucets. I also use those lines for the beer gun since they're already at lower pressure.
Also, if another tank/regulator is best, where can I find them cheap? I think our regulator was like $100+. Not really trying to spend that much.
If you think you're going to want to serve and carb at a bunch of different levels simultaneously I'd look at getting a bank of secondary regulators for inside your keezer. If you've got the tank outside you won't want a bunch of separate lines running in from multiple primaries.
I'm probably over-thinking this, just having a hard time wrapping my brain around it.