I have a dual regulator system, I use one regulator for carbing, and I use the other split three ways on a manifold for serving.
The serving regulator is driving me crazy. It just keeps going up slowly, so after about 5 hours, it's gained another 5 PSI or so.
I bleed the kegs, set regulator to 0 (unscrewed). Then, I slowly rotate screw so line pressure goes to 12 psi or so.
Unvariably, after a few hours, it's gone up to 15-18 psi. It is so annoying. I cannot figure out why it does this. I only have this problem with my serving regulator, not my carbing one.