After everytime my water softner recycles I get air in the line. It"s only on the first floor the second floor doesn"t seem to be affected. It takes quite awhile for the air to clear.
There was a brine float assembly that was out for awhile, still is but the rubber seal at the base of the float arm would go hard and break, letting air in and way to much water in the brine tank..
That float was plastic with 1/2" nut on the pickup tube and 3/8" on the brine line.. it is a copy of the Fleck 2310 saftey float..