My pressure switch had to be replaced recently. The old one was a 30-50 so I got the same thing. Since it's been in I have air in my pipes. Sometimes the pipes get airlocked and sometimes they just sputter. The holding tank is a steady 28 psi and the switch is set to 31 What could be causing the air.

I had a tiny leak in my iron baseboard in an attic kneewall, enough to constantly let water out (and down the inside of the outside wall, barely noticeable) and air in.