I have a nice hazy murky New Englad IPA carbonating now at 38 degrees and 14psi. It's only been under gas for about 24 hours. I was thinking of keeping at this low temp for a week or so and then warming up to 45 ish for serving. What should I do to dial in the pressure after warming? Should I vent the headspace and reset it to 14psi at 45 degrees (just about 2.4 vols)? Or do I not need to touch anything and just warm the beer up to 45 in my Keezer? I'm guessing that the pressure will get screwed up if I just warm it, but not sure how to figure that out.
If you do it ahead of time you shouldn't have a problem. Venting headspace too often just loses aromatics imo
If your keg's CO2 reaches equilibrium at 14 PSI at 38F, you're going to be around 2.8 Volumes of CO2. If you then warm it up to 45F you're going to be around 18 PSI, still at 2.8 Volumes. I think you'd need to do a bunch of venting to get back down to 2.4 volumes. Plus the aforementioned loss of aroma. For me, that's too much fiddling. If I wanted to carbonate to 2.4 volumes at 45F, I'd use about 14 PSI (13.7 to be more precise) at 45F. If you're in a big hurry, you could shake the keg.
If you plan to serve your beer at 45 and 18 psi you are asking for a head ache. Unless you have a good idea how to balance your system, calculate line length and can really maintain temps to within a degree or so you are headed for an awful lot of foam. It can be done but by the time you get it all sorted you will wonder why you began. Your best option is to serve at 38 and let it sit for a few minutes. Honest. Cheers.
I wouldn't bring it up to 45, but that's just me. I'd just keep it at 38. I was having problems with my kegerator being too warm (42ish) and all I got was foam. Not just first pour foam, 'all the time' foam. I modified the thermostat, and now that it's around 36-37 I get a perfect pour every time. Your call though obviously.
