Originally Posted by day_trippr
The "catch" is that secondary regulators need enough differential to work - but I'm not sure what that minimum differential might be.
If it was, say, 5 psi, your input rail to the secondaries would have to be 5 psi above the highest pressure you set the secondaries to. If you had one keg at 12 psi and another at 14, you'd need 19 psi at the input - which might be ok for a boisterous heffe, but little else.
Bottom line, before you cast your plans in concrete I'd try to find out what the minimum differential is for any secondary regulators under consideration...
Thanks for the advice, pressure deferential had never occured to me as an issue but it does make intuitive sense! I contacted Micro Matic, and got the following reply (looks like your "guess" at 5 PSI differential was spot-on, at least for Micro Matic regulators):"It is recommended to set your primary about 5 PSI over your highest secondary setting. For ex: You have 3 secondary’s and they are set at 10 PSI / 12 PSI and 15 PSI………set your primary at 20 PSI."
Guess I'll have to think about this a bit before I buy any equipment -- I would generally plan on using the primary regulator for force carbing and serving sodas/seltzer so wouldn't be a huge issue to have it 5+ PSI higher than the secondaries, but if I ever did want to run three beer kegs inside it could be an issue (perhaps requiring an additional splitter for one of the secondaries so I could run two kegs off of it if necessary).