I've now completed three lagers, Pilsner, Helles, Dark Lager with different yeasts, using pressure fermentation techniques. The yeasts were all built up from starters, the wort oxygenated via SS stone and O2 bottle, pitched and fermented at a target temp of 48 deg. The pressure rates were 2psi through 50% fermentation, ramped to 10psi to 75% fermentation, then ramped to 16psi and temp reduced over 2 days to 33 degrees.
Once at 33 degrees, I'll take a larger sample de-gas, use my hydrometer for a proper reading(refractometer used prior), and taste. I'm very familiar with the buttery feel/taste associated with Diacetyl and not one of my lagers has shown any signs.
I'm fully comfortable with the if it ain't broke policy but I wanted to put it to the more scientific folks within this forum to get your thoughts. The reason is it is quite a challenge to bring 10 gallons from 48 degrees to 58 or higher without using a heat source.
Is there any science to this or have I stumbled onto a good routine and I'll keep it routine?